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  • 1. Behrmann, Jan
    et al.
    Yan, J
    Bohnhoff, M
    Forster, A
    Pease, Victoria
    Stockholm University, Faculty of Science, Department of Geology and Geochemistry. Geology.
    ICDP drilling in convergent plate margins and collision zones.2007In: International Continental Drilling Program (ICDP), Springer , 2007Chapter in book (Other (popular science, discussion, etc.))
  • 2.
    Beranek, Luke P.
    et al.
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Pease, Victoria
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Scott, Robert A.
    Thomsen, Tonny B.
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Detrital zircon geochronology of Ediacaran to Cambrian deep-water strata of the Franklinian basin, northern Ellesmere Island, Nunavut: implications for regional stratigraphic correlations2013In: Canadian journal of earth sciences (Print), ISSN 0008-4077, E-ISSN 1480-3313, Vol. 50, no 10, 1007-1018 p.Article in journal (Refereed)
    Abstract [en]

    Enigmatic successions of deep-water strata referred to as the Nesmith beds and Grant Land Formation comprise the exposed base of the Franklinian passive margin sequence in northern Ellesmere Island, Nunavut. To test stratigraphic correlations with Ediacaran to Cambrian shallow-water strata of the Franklinian platform that are inferred by regional basin models, >500 detrital zircons from the Nesmith beds and Grant Land Formation were analyzed for sediment provenance analysis using laser ablation (LA-ICP-MS) and ion-microprobe (SIMS) methods. Samples of the Nesmith beds and Grant Land Formation are characterized by 1000-1300, 1600-2000, and 2500-2800 Ma detrital zircon age distributions and indicate provenance from rock assemblages of the Laurentian craton. In combination with regional stratigraphic constraints, these data support an Ediacaran to Cambrian paleodrainage model that features the Nesmith beds and Grant Land Formation as the offshore marine parts of a north-to northeast-directed depositional network. Proposed stratigraphic correlations between the Nesmith beds and Ediacaran platformal units of northern Greenland are consistent with the new detrital zircon results. Cambrian stratigraphic correlations within northern Ellesmere Island are permissive, but require further investigation because the Grant Land Formation provenance signatures agree with a third-order sedimentary system that has been homogenized by longshore current or gravity-flow processes, whereas coeval shallow-water strata yield a restricted range of detrital zircon ages and imply sources from local drainage areas or underlying rock units. The detrital zircon signatures of the Franklinian passive margin resemble those for the Cordilleran and Appalachian passive margins of Laurentia, which demonstrates the widespread recycling of North American rock assemblages after late Neoproterozoic continental rifting and breakup of supercontinent Rodinia.

  • 3.
    Beranek, Luke
    et al.
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Pease, Victoria
    Hadlari, Thomas
    Dewing, Keith
    Silurian flysch successions of Ellesmere Island, Arctic Canada, and their significance to northern Caledonian palaeogeography and tectonics2015In: Journal of the Geological Society, ISSN 0016-7649, E-ISSN 2041-479X, Vol. 172, no 2, 201-212 p.Article in journal (Refereed)
    Abstract [en]

    Detrital zircon provenance studies of Silurian flysch units that underlie the Hazen and Clements Markham fold belts of Ellesmere Island, Arctic Canada, were conducted to evaluate models for northern Caledonian palaeogeography and tectonics. Llandovery flysch was deposited along an active plate margin and yields detrital zircons that require northern derivation from the adjacent Pearya terrane. If Pearya originated near Svalbard and NE Greenland, it was transported by strike-slip faults to Ellesmere Island by the Early Silurian. Wenlock to Ludlow turbidites yield Palaeozoic-Archaean detrital zircons with dominant age-groupings c. 650, 970, 1150, 1450 and 1650 Ma. These turbidite systems did not fill a flexural foreland basin in front of the East Greenland Caledonides, but rather an east-west-trending trough that was probably related to sinistral strike-slip faulting along the northern Laurentian margin. The data support provenance connections with the Svalbard Caledonides, especially Baltican-affinity rocks of SW Spitsbergen that were proximal to NE Greenland during the Baltica-Laurentia collision. Pridoli flysch has sources that include Pearya, the East Greenland Caledonides and the Canadian Shield. Devonian-Carboniferous molasse in Arctic Canada has analogous detrital zircon signatures, which implies recycling of Silurian flysch during mid-Palaeozoic (Ellesmerian) collisional tectonism or that some collisional blocks were of similar Baltican-Laurentian crustal affinities.

  • 4.
    Bezenjani, R. Nasiri
    et al.
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Pease, Victoria
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Whitehouse, M. J.
    Shalaby, M. H.
    Kadi, K. A.
    Kozdroj, W.
    Detrital zircon geochronology and provenance of the Neoproterozoic Hammamat Group (Igla Basin), Egypt and the Thalbah Group, NW Saudi Arabia: Implications for regional collision tectonics2014In: Precambrian Research, ISSN 0301-9268, E-ISSN 1872-7433, Vol. 245, 225-243 p.Article in journal (Refereed)
    Abstract [en]

    Detrital zircon U-Pb SIMS dating is used to evaluate the provenance of two correlative basins in the Arabian-Nubian Shield (ANS). The Wadi Igla Formation in the Central Eastern Desert (CED) of Egypt and the Thalbah Group in the Midyan Terrane (MT) of NW Saudi Arabia are considered to be post-amalgamation terrestrial basins, developed during closure of the Mozambique Ocean and amalgamation of the ANS in Cryogenian-early Ediacaran time. The analytical results indicate that the upper-part of the Wadi Igla Formation has a maximum depositional age of 628 +/- 6 Ma, contains 98% Neoproterozoic zircon with ages between 815 and 628 Ma, and has two distinct peaks at 690 Ma and 652 Ma. A rhyolite clast from the upper-part of the Wadi Igla Formation gives a U-Pb age of 700 +/- 6 Ma. This age significantly predates Dokhan volcanism, indicating that the dominant rhyolitic clasts within the Wadi Igla Formation are not from the Dokhan Volcanics, as previously believed. Analytical results from the Thalbah Group suggest multiphase basin formation and development. The lower part of the Thalbah Group is intruded by monzogranites of the Liban complex, has a minimum depositional age of 635 +/- 5 Ma, resembling that of the Wadi Igla Formation. Its middle part has a maximum age of 612 +/- 7 Ma and is comprised of 90% Neoproterozoic zircon with ages ranging from 820 to 612 Ma. The upper part of the Thalbah Group has a maximum age of 596 +/- 10 Ma and contains a wider range of Neoproterozoic detritus with ages between 985 and 596 Ma. The basement of the Thalbah Group is represented by metasediments and metavolcanics of the Zaam Group. The sample collected from the uppermost part of the Zaam Group (Um Ashsh Formation) contains zircon of mostly Cryogenian age (ca. 812-697 Ma) and has a maximum age of 700 +/- 4 Ma, suggesting that the Zaam Group might be correlative with the subduction-related metavolcanic and metasedimentary rocks that are overlain unconformably by the Wadi Igla Formation in the CED. The Wadi Igla basin and the lower and middle parts of the Thalbah basin have similar provenance, record a Cryogenian-early Ediacaran age, and represent syn-subduction (rather than post-amalgamation) basins. The upper part of the Thalbah Group, in contrast, has a distinct provenance representing an Ediacaran syn-collisional basin. The narrow age range of the Wadi Igla Formation and the lower and middle parts of the Thalbah Group indicates a restricted source from the CED and MT island arc basement, whereas the wide age range for the upper part of the Thalbah Group indicates a contribution from other parts of the ANS. The sediment sources and the age patterns of detrital zircons change abruptly at ca. 596 Ma. This may coincide with the onset of collision of the CED and MT basements with the older Hijaz-Gebeit terrane (850-680 Ma) to the south along the Yanbu-Onib-Sol Hamed-Gerf-Allaqi-Heiani (YOSHGAH) suture in the ANS during the East African Orogeny.

  • 5. Bogolepove, Olga
    et al.
    Gubanov, Alexander
    Pease, Victoria
    Stockholm University, Faculty of Science, Department of Geology and Geochemistry. Geology.
    The Ordovician of the Severnaya Zemlya Archipelago, Russia.2006In: Newsletters on StratigraphyArticle in journal (Refereed)
  • 6. Condie, Kent
    et al.
    Pease, Victoria
    Stockholm University, Faculty of Science, Department of Geology and Geochemistry. Geology.
    When did plate tectonics begin on planet Earth?2008Book (Other (popular science, discussion, etc.))
  • 7. Jarrar, Ghaleb H.
    et al.
    Stern, Robert J.
    Theye, Thomas
    Yaseen, Najel
    Pease, Victoria
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Miller, Nathan
    Ibrahim, Khalil M.
    Passchier, Cees W.
    Whitehouse, Martin
    Neoproterozoic Rosetta Gabbro from northernmost Arabian-Nubian Shield, south Jordan: Geochemistry and petrogenesis2017In: Lithos, ISSN 0024-4937, E-ISSN 1872-6143, Vol. 284, 545-559 p.Article in journal (Refereed)
    Abstract [en]

    An Ediacaran mafic intrusion of south Jordan is a distinctive appinitic igneous rock with a possibly unique texture, characterized by spherical clots up to 40 mm in diameter composed of amphibole cores from which plagioclase euhedra radiate; we call it the Rosetta Gabbro. It is exposed as a small (ca. 750 m(2)) outcrop in the Neoproterozoic basement of south Jordan. A second outcrop of otherwise similar gabbro is located about 400 m to the north of the Rosetta Gabbro, but it lacks the distinctive texture. The Rosetta Gabbro could represent a magma pipe. It intrudes the Aqaba Complex (similar to 600 Ma) granitoids and metasediments of the Janub Metamorphic Complex (633-617 Ma). The gabbro is an 01- to QZ tholeiite with the following chemical characteristics: SiO2 = 46.2-47.8 wt.%; Al2O3 = 16.4-17.7 wt.%, TiO2 = 1.70-2.82 wt.%, Na2O = 1.27-2.83 wt.%. K2O = 0.82-1.63 wt.%; Mg# 58-63; Sigma REE = 70-117 ppm; La/Yb similar to 6 to 8; and Eu/Eu* = 1.05-1.2. The investigated gabbro has the geochemical features of a continental flood tholeiitic basalt emplaced in a within-plate tectonic setting. Two varieties of amphiboles are found: 1) large, 3-5 mm, brown ferri-titanian-tschermakite K0.09Na0.28) (Na020Ca1.80) (Mn0.04Fe1.13+Mg2.34Fe0.902+Ti029Al0.22)(Al-1.Si-85(6.15))O-22(OH)(1.95) of the calcic amphibole group which is riddled with opaques; and 2) acicular yellowish-light green ferrian-magnesiohomblende (K0.04Na0.153)(Ca1.755Na0245) (Fe(0.66)(3+)Mn(0.01)Fe(1.01)(2+)mg(3.03)Ti(0.06)Al(0.22))(Al1.03Si6.97)O-22(OH)1.95. Scattered flakes of phlogopite also occur. Tabular radiating plagioclase (An(64-79)) are complexly twinned, with broad lamellae that show no zoning. Laser-ablation ICP-MS analyses of amphibole and plagioclase reveal considerable variation in trace element abundance, in spite of more subtle major element variations except for TiO2 in amphibole. The REE in the amphibole shows an order of magnitude variation with a concave-downward pattern and a positive Eu anomaly Eu/Eu* = 0.6-2, though far less pronounced compared to the Eu/Eu* = 5-45 of plagioclase. The 3D dandelion-like texture of the rosettas is broadly similar to Chrysanthemum Stone, which is a diagenetic growth in sedimentary rock, but we can find no description of similar textures in igneous rocks. The formation of the rosettas is thought to reflect loss of magmatic water resulting in supersaturation of plagioclase, which grew rapidly around amphibole and may havelloated in the magma. This implies magmatic evolution in shallow (10 to 12 km deep) crust where temperatures were nevertheless in the range of ca. 750 to 900 degrees C.

  • 8. Jarrar, Ghaleb H.
    et al.
    Theye, Thomas
    Yaseen, Najel
    Whitehouse, Martin
    Pease, Victoria
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Passchier, Cees
    Geochemistry and P-T-t evolution of the Abu-Barqa Metamorphic Suite, SW Jordan, and implications for the tectonics of the northern Arabian-Nubian Shield2013In: Precambrian Research, ISSN 0301-9268, E-ISSN 1872-7433, Vol. 239, 56-78 p.Article in journal (Refereed)
    Abstract [en]

    The Abu Barqa Metamorphic Suite (ABMS) represents the oldest part of the Arabian-Nubian Shield in southern Jordan. It comprises tonalitic gneiss, metasediments including schist and paragneiss, and granitic gneiss, intruded by later granitic bodies. Geochemically, the majority of the schist samples have shale and Fe-shale protoliths, while the paragneisses represent metagreywacke. Tectonic discrimination diagrams indicate that the protolith of the ABMS was deposited at an active continental margin/island arc setting. U-Pb zircon (SIMS) ages from metamorphic and igneous rocks of the ABMS indicate that it evolved between similar to 800 and similar to 610 Ma. A tonalitic gneiss has a crystallization age of 787 +/- 3 Ma. Detrital zircon from the metasediment has a range of concordant ages from 680 to 860 Ma. The entire metamorphic complex was intruded by calc-alkaline granitoids (similar to 615-610 Ma) and quartz diorite dated (similar to 600 Ma). Field and petrographic investigations of ABMS metasediment elucidate the development of three metamorphic zones, from north to south: (1) andalusite-staurolite (andalusite + staurolite + biotite + muscovite + plagioclase +/- garnet + quartz +/- chlorite + fibrolitic sillimanite + accessories), (2) garnetsillimanite (sillimanite + garnet + biotite + plagioclase + quartz + K-feldspar + cordierite (pinitized) +/- rutile +/- ilmenite), and (3) cordierite-sillimanite (sillimanite + biotite + plagioclase + cordierite + hercynite + quartz + accessories). The maximum metamorphic conditions (M1) were attained in the garnet-sillimanite zone (5-6 kbar, similar to 700 degrees C), while peak conditions of similar to 3.2 kbar and 540 degrees C were obtained for the andalusite-staurolite zone (using both forward-pseudosection modeling and inverse-modeling with multi-equilibrium approach). Compositional isopleth calculations of small relics of garnet yield about 3.5 kbar and 600 degrees C for the sillimanite-cordierite zone. These values are in agreement with results obtained by TWQ inverse modeling. The M1 event most probably occurred around similar to 625 and was followed by a decompressional thermal phase (M2) contemporaneous with post-tectonic granitoid emplacement at similar to 615-610 Ma; and lastly went through a retrograde cooling phase (M3) accompanying uplift of the whole complex to the surface at similar to 605 Ma.

  • 9. Kirkland, C.
    et al.
    Pease, Victoria
    Stockholm University, Faculty of Science, Department of Geology and Geochemistry.
    Whitehouse, M.
    Ineson, J.
    Provenance of the Inuiteq Sø and Moraenesø formations of Peary Land: Implications for the unexposed crystalline basement of Greenland.2007In: V International Conference of Arctic Margins Abstract Volume, NGF,, 2007, 52-53 p.Conference paper (Other academic)
  • 10. Kirkland, C.
    et al.
    Whitehouse, Martin
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Pease, Victoria
    Stockholm University, Faculty of Science, Department of Geology and Geochemistry.
    Van Kranendonk, M.
    Oxygen isotopes in detrital zircons insight into crustal recycling during the evolution of the Greenland Shield2010In: Lithosphere, ISSN 1941-8264, E-ISSN 1947-4253, Vol. 2, no 1, 3-12 p.Article in journal (Refereed)
    Abstract [en]

    Insight into the interactions between crust and hydrosphere, through the protracted evolution of the Greenland Shield, can be provided by oxygen isotopes in the mineral remnants of its denuded crust. Detrital zircons with ages of 3900 Ma to 900 Ma found within an arkosic sandstone dike of the Neoproterozoic (?Marinoan) Mørænesø Formation, North Greenland, provide a time-integrated record of the evolution of part of the Greenland Shield. These zircon grains are derived from a wide variety of sources in northeastern Laurentia, including Paleoproterozoic and older detritus from the Committee-Melville orogen, the Ellesmere-Inglefield mobile belt, and the subice continuation of the Victoria Fjord complex. Archean zircon crystals have a more restricted range of δ18OSMOW values (between 7.2‰ and 9.0‰ relative to standard mean ocean water [SMOW]) in comparison to Paleoproterozoic 1800–2100 Ma grains, which display significant variation in δ18OSMOW (6.8‰–10.4‰). These data reflect differences in crustal evolution between the Archean and Proterozoic Earth. Through time, remelting or reworking of high δ18O materials has become more important, consistent with the progressive emergence of buoyant, cratonized continental lithosphere. A secular increase in the rate of crustal recycling is implied across the Archean-Proterozoic boundary. This rate change may have been a response to differences in the composition of sediments and/or the stabilization of continental crust.

    One Eoarchean oscillatory-zoned zircon grain, free of cracks and with concordant U-Pb systematics, has an elevated δ18OSMOW value of 7.8‰. This is interpreted to reflect a primary magmatic signature, supporting the presence of heavy oxygen that may be compatible with a hydrosphere on early Earth, as previously determined only from Jack Hills zircons.

  • 11. Kirkland, Chris
    et al.
    Pease, Victoria
    Stockholm University, Faculty of Science, Department of Geology and Geochemistry. Geology.
    Whitehouse, Martin
    Ineson, Jon
    Provenance record of Proterozoic strata from Peary Land, North Greenland: Implications for the unexposed crystalline basement of Greenland, its evolution and Neoproterozic paleodrainage & paleogeography.2009In: Precambrain Research, Vol. 170, no 1-2, 43-60 p.Article in journal (Refereed)
  • 12. Kuzmichev, A.
    et al.
    Pease, Victoria
    Stockholm University, Faculty of Science, Department of Geology and Geochemistry. Stockholm University, Faculty of Science, Department of Geology and Geochemistry.
    Siberian trap magmatism on the New Siberian Islands: Constraints for east Arctic Mesozoic plate tectonic reconstructions.2007In: Journal of the Geological Society (London), Vol. 164, 959-968 p.Article in journal (Refereed)
  • 13. Kuzmichev, Alexander
    et al.
    Pease, Victoria
    Stockholm University, Faculty of Science, Department of Geology and Geochemistry. Geology.
    Siberian trap magmatism on the New Siberian Islands: Constraints for east Arctic Mesozoic plate tectonic reconstructions2007In: Journal of the Geological Society, Vol. 164, 959-968 p.Article in journal (Refereed)
  • 14. Ledneva, G.
    et al.
    Pease, Victoria
    Stockholm University, Faculty of Science, Department of Geology and Geochemistry.
    Sokolov, S.
    Miller, E.
    Shcherbakov, V.
    Petrology and age of hypabbysal intrusive rocks of Koluchin Bay, Chukotka Peninsula, Russia.2007In: V International Conference of Arctic Margins Abstract Volume, NGF, 2007, 114- p.Conference paper (Other academic)
  • 15. Ledneva, G. V.
    et al.
    Pease, Victoria L.
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Bazylev, B. A.
    Late Triassic siliceous-volcano-terrigenous deposits of the Chukchi Peninsula: composition of igneous rocks, U-Pb age of zircons, and geodynamic interpretations2016In: Russian Geology and Geophysics, ISSN 1068-7971, E-ISSN 1878-030X, Vol. 57, no 8, 1119-1134 p.Article in journal (Refereed)
    Abstract [en]

    Study of Late Triassic volcanic, subvolcanic, and volcanosedimentary rocks of the Chukchi Peninsula (Vel'may terrane) has shown their different geochemical types. Basalts, dolerites, and tuffs of the lower-middle strata of the Upper Triassic section bear evidence for their formation in suprasubductional geodynamic setting. Basalts and dolerites of the upper strata of this section correspond in composition to within-plate rocks and are similar to Middle-Late Triassic oceanic-plateau basalts and dolerites. U-Pb dating of magmatic zircons from tuffs of the lower-middle strata and from dolerites of the upper strata shows the almost synchronous magmatic activity in the suprasubductional (206 +/- 5 Ma) and within-plate (212 +/- 4 Ma) geodynamic settings. (C) 2016, V.S. Sobolev IGM, Siberian Branch of the RAS.

  • 16. Ledneva, Galina V.
    et al.
    Pease, Victoria L.
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Sokolov, Sergey D.
    Permo"Triassic hypabyssal mafic intrusions and associated tholeiitic basalts of the Kolyuchinskaya Bay, Chukotka (NE Russia): Links to the Siberian LIP2011In: Journal of Asian Earth Sciences, ISSN 1367-9120, E-ISSN 1878-5786, Vol. 40, no 3, 737-745 p.Article in journal (Refereed)
    Abstract [en]

    In order to test tectonic hypotheses regarding the evolution of the Arctic Alaska-Chukotka microplate prior to the opening of the Amerasian basin, we investigated rocks exposed near Kolyuchinskaya Bay, eastern Chukotka. Hypabyssal mafic rocks and associated basaltic flows enclose terrigenous sediments, minor cherts and limestones in pillow interstices. The hypabyssal mafic rock yields a U-Pb zircon age of 252 +/- 4 Ma and indicates intrusion of basic magma at the Permo-Triassic boundary, contemporaneous with voluminous magmatism of the Siberian large igneous province (LIP). The lava flows and hypabyssal mafic rocks of the Kolyuchinskaya Bay region have trace elements, Sm-Nd and Rb-Sr isotope compositions identical to the tholeiitic flood basalts of the main plateau stage of the Siberian LIP, but differ from the latter in the major-element variations. We conclude that compositional variations in the hypabyssal rocks studied reflect their generation in an extensional environment that might be related to the Siberian super-plume activity at the time. Although the genetic and temporal links between intrusive mafic rocks and lavas are not well proved, compositional variations of the eruptive rocks still indicate their generation in an extensional environment.

  • 17. Li, Nuo
    et al.
    Ulrich, Thomas
    Chen, Yan-Jing
    Thomsen, Tonny B.
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Pease, Victoria
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Pirajno, Franco
    Fluid evolution of the Yuchiling porphyry Mo deposit, East Qinling, China2012In: Ore Geology Reviews, ISSN 0169-1368, E-ISSN 1872-7360, Vol. 48, 442-459 p.Article, review/survey (Refereed)
    Abstract [en]

    The Yuchiling Mo deposit, East Qinling, China, belongs to a typical porphyry Mo system associated with high-K calc-alkaline intrusions. The pure CO2 (PC), CO2-bearing (C), aqueous H2O-NaCI (W), and daughter mineral-bearing (S) fluid inclusions were observed in the hydrothermal quartz. Based on field investigations, petrographic, microthermometric and LA-ICP-MS studies of fluid inclusions, we develop a five-stage fluid evolution model to understand the ore-forming processes of the Yuchiling deposit. The earliest barren quartz +/- potassic feldspar veins, developed in intensively potassic alteration, were crystallized from carbonic-dominant fluids at high temperature (>416 degrees C) and high pressure (>133 MPa). Following the barren quartz potassic feldspar veins are quartz-pyrite veins occasionally containing minor K-feldspar and molybdenite, which were formed by immiscible fluids at pressures of 47-159 MPa and temperatures of 360-400 degrees C. The fluids were characterized by high CO2 contents (approximately 8 mol%) and variable salinities, as well as the highest Mo contents that resulted in the development of quartz-molybdenite veins. The quartz-molybdenite veins, accounting for >90% Mo in the orebody, were also formed by immiscible fluids with lower salinity and lower CO2 content of 7 mol%, at temperatures of 340-380 degrees C and pressures of 39-137 MPa, as constrained by fluid inclusion assemblages. After the main Mo-mineralization, the uneconomic Cu-Pb-Zn mineralization occurred, as represented by quartz-polymetallic sulfides veins consisting of pyrite, molybdenite, chalcopyrite, digenite, galena, sphalerite and quartz. The quartz-polymetallic sulfide veins were formed by fluids containing 5 mol% CO2, with minimum pressures of 32-110 MPa and temperatures of 260-300 degrees C. Finally, the fluids became dilute (5 wt.% NaCI equiv) and CO2-poor, which caused the formation of late barren quartz+ carbonate fluorite veins at 140-180 degrees C and 18-82 MPa. It is clear that the fluids became more dilute, CO2-poor, and less fertile, with decreasing temperature and pressure from quartz-pyrite to late barren veins. Molybdenite and other sulfides can only be observed in the middle three stages, i.e., quartz-pyrite, quartz-molybdenite and quartz-polymetallic sulfide veins. These three kinds of veins are generally hosted in potassic altered rocks with remarkable K-feldspathization, but always partly overprinted by phyllic alteration. The traditional porphyry-style potassic-phyllic-propylitic alteration zoning is not conspicuous at Yuchiling, which may be related to, and characteristic of, the CO2-rich fluids derived from the magmas generated in intercontinental collision orogens. Among the fluid inclusions at Yuchiling, only the C-type contains maximum detectable Mo that gradationally decreases from 73 ppm in quartz-pyrite veins, through 19 ppm in quartz-molybdenite veins, and to 13 ppm in quartz-polymetallic sulfide veins, coinciding well with the decreasing CO2 contents from 8 mol%, through 7 mol%, to 5 mol%, respectively. Hence it is suggested that decreasing CO2 possibly results in decreasing Mo concentration in the fluids, as well as the precipitation of molybdenite from the fluids. This direct relationship might be a common characteristic for other porphyry Mo systems in the world. The Yuchiling Mo deposit represents a new type Mo mineralization, with features of collision-related setting, high-K calc-alkaline intrusion, CO2-rich fluid, and unique wall-rock alterations characterized by strong K-feldspathization and fluoritization.

  • 18. Li, Zeng
    et al.
    Bogdanova, Svetlana
    Collins, Alan
    Davidson, Anthony
    DeWaele, Bert
    Ernst, Richard
    Fitzsimons, Ian
    Pease, Victoria
    Stockholm University.
    Assembly, configuration, and break-up history of Rodinia: A synthesis.2008In: Precambrain ResearchArticle in journal (Refereed)
  • 19. Miller, E. L.
    et al.
    Gehrels, G. E.
    Pease, Victoria
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Sokolov, S.
    Stratigraphy and U-Pb detrital zircon geochronology of Wrangel Island, Russia: Implications for Arctic paleogeography2010In: American Association of Petroleum Geologists Bulletin, ISSN 0149-1423, E-ISSN 1558-9153, Vol. 94, no 5, 665-692 p.Article in journal (Refereed)
    Abstract [en]

    Wrangel Island represents a small but unique exposure of Neoproterozoic basement and its upper Paleozoic and Mesozoic cover within the mostly unexplored East Siberian Shelf. Its geology is critical for testing the continuity of stratigraphic units and structures across the Chukchi Sea from Alaska to Arctic Russia, for evaluating the hydrocarbon potential of this offshore region, and for constraining paleogeography and plate reconstructions of the Arctic. Upper Paleozoic platform carbonates and shales on Wrangel likely match those of the Chukchi Shelf and adjacent North Slope of Alaska (e.g., Sherwood et al., 2002), but Triassic basinal turbidites contrast with Alaska's thin shelfal units. Detrital zircon suites from upper Paleozoic strata on Wrangel reveal that local basement-derived detritus (similar to 500-800 Ma) decreases up section, replaced by 900-2000-Ma zircon populations compatible with a Baltic shield provenance. Cambrian-Ordovician-Silurian zircons (similar to 420-490 Ma) are present in lesser abundance in most samples and are inferred to have been derived from the Arctic part of the Caledonide belt. Triassic detrital zircon suites contrast with those from underlying strata: Precambrian zircons have less of an age range (1700-2000 Ma), and Devonian and younger (<400 Ma) zircons are much more abundant. This change reflects breakup of the carbonate platform during Permian-Triassic rifting, with zircon age populations in Triassic strata compatible with sediment sources in the Urals, Taimyr, and Siberia. Detrital zircon data suggest that Wrangel Island, Chukotka, and northern Alaska (the Arctic Alaska-Chukotka microplate) restore against the Lomonosov Ridge upon closure of the Amerasia Basin and to the edge of the Barents Shelf after closing the Eurasia Basin. The detrital zircon data thus suggest that the Barents Shelf lays close to the paleo-Pacific margin in the early Mesozoic and that subduction-driven tectonics may have been a greater factor in the evolution of the Amerasia Basin of the Arctic than previously suspected.

  • 20. Morris, G.
    et al.
    Pease, Victoria
    Stockholm University, Faculty of Science, Department of Geology and Geochemistry.
    U-Pb zircon provenance of late Neoproterozoic and early Paleozoic sediments from northern Greenland.2007In: V International Conference of Arctic Margins Abstract Volume, NGF, 2007, 25- p.Conference paper (Other academic)
  • 21. Morris, George A.
    et al.
    Kirkland, C. L.
    Pease, Victoria
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Orogenic paleofluid flow recorded by discordant detrital zircons in the Caledonian foreland basin of northern Greenland2015In: Lithosphere, ISSN 1941-8264, E-ISSN 1947-4253, Vol. 7, no 2, 138-143 p.Article in journal (Refereed)
    Abstract [en]

    Concordant detrital zircon dates from Neoproterozoic to Paleozoic continental slope and trough deposits in northern Greenland indicate Late Archean and Paleoproterozoic sediment sources. Significant numbers of dates are, however, discordant and, together with a few apparently concordant dates, give ages younger than the depositional ages of overlying fossiliferous sediments. The discordance pattern implies partial or total radiogenic-Pb loss during the Middle Devonian, possibly facilitated by postdepositional fluid movement. Such timing of radiogenic-Pb loss is supported by results from a novel modeling method, which indicate that the greatest statistical similarity between concordant and discordant detrital populations occurs when Pb loss is constrained to the interval of 380-390 Ma, i.e., long after deposition. This radiogenic-Pb loss event is interpreted to reflect fluid flow associated with Caledonian orogenic uplift to the east.

  • 22. Omma, J.
    et al.
    Pease, Victoria
    Stockholm University, Faculty of Science, Department of Geology and Geochemistry.
    Scott, R.
    Embry, A.
    U-Pb SIMS zircon geochronology of Mesozoic sandstones on northwestern Axel Heiberg Island, Nunavut2011In: Geological Society of America. Memoirs, ISSN 0072-1069, Vol. 35, 559-566 p.Article in journal (Refereed)
    Abstract [en]

    Detrital U–Pb zircon age data from five stratigraphically controlled Mesozoic sandstones collected from a relatively continuous section in northwestern Axel Heiberg Island are used to evaluate the sediment dispersal patterns and source areas of the northern Sverdrup Basin. Three distinctive provenance types are identified. Early Triassic, Late Triassic and Middle Jurassic samples are dominated by Permo-Triassic zircons and are inferred to be derived from the Taimyr Peninsula/Polar Urals, the New Siberian Islands or some unexposed source submerged beneath the Arctic Ocean. The presence of chrome spinel in these samples suggests a component of mafic–ultramafic material in the source. An Early Jurassic sample is dominated by late Neoproterozoic–early Silurian zircons, which correlate with the Caledonian and Timanian orogens of the Barents Shelf region. A Late Jurassic sample is dominated by Meso-, Palaeoproterozoic and Archaean zircons interpreted to be sourced from the Canada–Greenland shield.

  • 23. Omma, J.
    et al.
    Scott, R.
    Pease, Victoria
    Stockholm University, Faculty of Science, Department of Geology and Geochemistry.
    Embry, A.
    Morton, A.
    Provenance of northerly-derived sediments in the Sverdrup Basin, Arctic Canada.2007In: V International Conference of Arctic Margins Abstract Volume, NGF, 2007, 115- p.Conference paper (Other academic)
  • 24.
    Pease, Victoria
    Stockholm University, Faculty of Science, Department of Geology and Geochemistry. Geology.
    Swedarctic 2006 – The Development of the Arctic Ocean.2006Other (Other (popular science, discussion, etc.))
  • 25.
    Pease, Victoria
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Tectonics of Eurasian Arctic Orogens: An Overview2011In: Geological Society of America. Memoirs, ISSN 0072-1069, Vol. 35, 311-324 p.Article in journal (Refereed)
    Abstract [en]

    This review summarizes our current understanding of the major Eurasian orogens in the context of Arctic tectonics: the Ediacaran Timanides, the middle Palaeozoic Caledonides, the late Palaeozoic Uralides and the Mesozoic fold belts of Taimyr and erkhoyansk. Controversies and problems are associated with the: (i) regional extent, timing, and nature of deformation associated with Ediacaran Timanian orogenesis; (ii) northward extent of Caledonian deformation; (iii) continuation of Permo-Carboniferous Uralian orogenesis on Novaya Zemlya and understanding this deformation in Taimyr; (iv) timing, location and style of deformation   associated with Mesozoic deformation in Taimyr and Verkhoyansk, and its relationship to the opening of the Amerasia Basin; (v) original size of the Arctic Alaska–Chukotka microplate (AACM) and the nature of its boundaries, including the timing and amount of extension of the AACM and the location of the South Anyui Suture; and (vi) age and nature of pre-Okhotsk–Chukotka volcano-plutonic belt basement across eastern Russia and western Alaska and its relationship to the development of the Canada Basin/Amerasia Basin. The resolution of these controversies is needed to test hypotheses for the tectonic development of the Amerasia Basin, in particular, and for understanding the tectonic development of the Circum-Arctic as a whole.

  • 26.
    Pease, Victoria
    Stockholm University, Faculty of Science, Department of Geology and Geochemistry.
    Wrangel Island, a jewel of the Arctic.2007In: AGU conference proceedings, 2007, CD-ROM p.Conference paper (Other academic)
  • 27.
    Pease, Victoria
    et al.
    Stockholm University, Faculty of Science, Department of Geology and Geochemistry. Geology.
    Daly, Stephen
    Elming, Sten-Åke
    Kumpulainen, Risto
    Moczydlowska, Malgosia
    Baltica in the Cryogenian, 850-650 Ma2008In: Precambrain ResearchArticle in journal (Refereed)
  • 28.
    Pease, Victoria
    et al.
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Drachev, S.
    Stephenson, R.
    Zhang, Xiaojing
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Arctic lithosphere - A review2014In: Tectonophysics, ISSN 0040-1951, E-ISSN 1879-3266, Vol. 628, 1-25 p.Article, review/survey (Refereed)
    Abstract [en]

    This article reviews the characteristics of Arctic lithosphere and the principal tectonic events which have shaped it. The current state-of-knowledge associated with the crust, crustal-scale discontinuities, and their ages, as well as knowledge of the lithosphere as a whole from geophysical data, permits the division of Arctic lithosphere into discrete domains. Arctic continental lithosphere is diverse in age, composition, and structure. It has been affected by at least two periods of thermal overprinting associated with large volumes of magmatism, once in the Permo-Triassic and again in the Aptian. In addition, it was attenuated as the result of at least five phases of rifting (in the late Devonian-early Carboniferous, Permo-Triassic, Jurassic, Early Cretaceous, and Late Cretaceous-Cenozoic). Older phases of consolidation are associated with continental lithosphere and occurred through a series of continent-continent collisions in the Paleozoic. Jurassic and Cretaceous extensional phases are related to the dismembering of Pangea and Eurasia, and were concentrated in the Norway-Greenland and Canadian-Alaskan Arctic regions. Large areas of submarine, hyperextended continental (?) lithosphere developed in parts of the Amerasia Basin. After continental breakup and the accretion of new oceanic lithosphere, the Eurasia and Canada basins were formed.

  • 29.
    Pease, Victoria
    et al.
    Stockholm University, Faculty of Science, Department of Geology and Geochemistry.
    Kosteva, N.
    Tebenkov, A.
    Markarjeva, E.
    Markarjev, A.
    U-Pb zircon provenance of Late Triassic sandstone from Franz Josef Land.2007In: V International Conference of Arctic Margins Abstract Volume, NGF,, 2007, 123- p.Conference paper (Other academic)
  • 30.
    Pease, Victoria L.
    et al.
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Kuzmichev, Alexander B.
    Danukalova, Maria K.
    The New Siberian Islands and evidence for the continuation of the Uralides, Arctic Russia2015In: Journal of the Geological Society, ISSN 0016-7649, E-ISSN 2041-479X, Vol. 172, 1-4 p.Article in journal (Refereed)
    Abstract [en]

    U–Pb detrital zircon results from New Siberian Islands sandstones illuminate the long-lived controversy regarding the continuation of the Uralian orogen into the Arctic region. A dominant age peak of c. 285 Ma from Permian sandstone requires proximal derivation from Taimyr’s Carboniferous–Permian granites, thought to reflect syn- to post-tectonic Uralian magmatism. The provenance of Devonian sandstone has Baltica affinities. The data record a dramatic change in provenance between Devonian and Permian time, from Baltica to a mixed Baltica + Uralian source. Our results confirm that the Uralian foreland basin extended from Taimyr to the New Siberian Islands.

  • 31.
    Pease, Victoria
    et al.
    Stockholm University, Faculty of Science, Department of Geology and Geochemistry.
    Miller, E.
    Sokolov, S.
    New age relationships from Chukotka, Russia, and implications for the opening of the Amerasia Basin.2007In: V International Conference of Arctic Margins Abstract Volume, NGF,, 2007, 113- p.Conference paper (Other academic)
  • 32.
    Pease, Victoria
    et al.
    Stockholm University, Faculty of Science, Department of Geology and Geochemistry. Geology.
    Percival, John
    Smithies, Hugh
    Stevens, Gary
    Van Krankonk, Martin
    When did plate tectonics begin? Evidence from the orogenic record.2008In: When did plate tectonics begin on planet Earth?, Geological Society of America , 2008Chapter in book (Refereed)
  • 33.
    Pease, Victoria
    et al.
    Stockholm University, Faculty of Science, Department of Geology and Geochemistry. Geology.
    Persson, Stefan
    Neoproterozoic island arc magmatism of northern Taimyr2006In: Mineral Management ServicesArticle in journal (Refereed)
  • 34.
    Pease, Victoria
    et al.
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Scarrow, J. H.
    Nobre Silva, Ines G.
    Stockholm University, Faculty of Science, Department of Geological Sciences. Memorial University of Newfoundland, Canada.
    Cambeses, A.
    Devonian magmatism in the Timan Range, Arctic Russia - subduction, post-orogenic extension, or rifting?2016In: Tectonophysics, ISSN 0040-1951, E-ISSN 1879-3266, Vol. 691, 185-197 p.Article in journal (Refereed)
    Abstract [en]

    Devonian mafic magmatism of the northern East European Craton (EEC) has been variously linked to Uralian subduction, post-orogenic extension associated with Caledonian collision, and rifting. New elemental and isotopic analyses of Devonian basalts from the Timan Range and Kanin Peninsula, Russia, in the northern EEC constrain magma genesis, mantle source(s) and the tectonic process(es) associated with this Devonian volcanism to a rift-related context. Two compositional groups of low-K2O tholeiitic basalts are recognized. On the basis of Th concentrations, LREE concentrations, and (LREE/HREE)(N), the data suggest two distinct magma batches. Incompatible trace elements ratios (e.g., Th/Yb, Nb/Th, Nb/La) together with Nd and Pb isotopes indicate involvement of an NMORB to EMORB 'transitional' mantle component mixed with variable amounts of a continental component. The magmas were derived from a source that developed high (U,Th)/Pb, U/Th and Sm/Nd over time. The geochemistry of Timan-Kanin basalts supports the hypothesis that the genesis of Devonian basaltic magmatism in the region resulted from local melting of transitional mantle and lower crust during rifting of a mainly non volcanic continental rifted margin.

  • 35.
    Pettersson, Carl Henrik
    et al.
    Stockholm University, Faculty of Science, Department of Geology and Geochemistry.
    Pease, Victoria
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Frei, Dirk
    Geological Survey of Denmark and Greenland (GEUS), .
    Detrital zircon U-Pb ages of Silurian-Devonian sediments from NW Svalbard: A fragment of Avalonia and Laurentia?2010In: Journal of the Geological Society (London), Vol. 167, no 5, 1019-1032 p.Article in journal (Refereed)
    Abstract [en]

    Detrital zircon populations from Silurian-Devonian clastic rocks of NW Svalbard were analysed by U-Pb laser ablation inductively coupled plasma mass spectrometry to investigate the pre-Caledonian provenance of Svalbard's Northwestern Terrane. Changes in the resulting age spectra suggest a major shift in sources from the Laurentian-Avalonian suture in the latest Silurian to the local metasedimentary basement of the Northwestern Terrane in the Late Silurian-Early Devonian, and in the Lochkovian to Grenvillian-Sveconorwegian sources. These data, together with structural, additional geochronological and metamorphic data from Svalbard, East Greenland and Avalonia, support the amalgamation of Svalbard as the result of long-distance transport along sinistral strike-slip faults. A unifying model for the final amalgamation of Svalbard, consistent with the stratigraphical and tectonothermal history of Svalbard, involves fragments from the Grampian orogen and Avalonian crust originally accreted to the Laurentian margin being subsequently transported northward along sinistral strike-slip faults during Scandian deformation.

  • 36.
    Pettersson, Carl Henrik
    et al.
    Stockholm University, Faculty of Science, Department of Geology and Geochemistry.
    Tebenkov, A.
    Larionov, A.
    Andresen, A.
    Pease, Victoria
    Stockholm University, Faculty of Science, Department of Geology and Geochemistry.
    Timing of migmatization and granite genesis of the Northwestern Terrane, Svalbard2009In: Journal of the Geological Society, ISSN 0016-7649, E-ISSN 2041-479X, Vol. 166, 147-158 p.Article in journal (Refereed)
    Abstract [en]

    U–Pb ion microprobe investigations of zircons from gneisses, granites and migmatites of the pre-Devonian Smerenburgfjorden and Richarddalen Complexes constrain the tectonic evolution and origin of Svalbard's Northwestern Terrane. Field relationships combined with U–Pb age data indicate that a late Meso- to Neoproterozoic metapelitic protolith was intruded by Tonian (c. 960 Ma) granitoids and suggest that the entire Northwestern Terrane is underlain by early Neoproterozoic granitoids intruding older metasediments. Both rock types were later involved in Caledonian deformation, with subsequent migmatization and granite genesis at c. 435–420 Ma. Ages of inherited zircons in granites and migmatites reflect anatexis of this late Meso- to Neoproterozoic protolith, with zircon xenocrysts ranging in age from c. 1030 to 1820 Ma. Pronounced lithological, geochronological and tectonothermal similarities to NE Svalbard (Nordaustlandet) and the Krummedal supracrustal sequence of East Greenland suggest a strong correlation between Svalbard and East Greenland prior to Caledonian orogenesis.

  • 37.
    Pettersson, Carl-Henrik
    et al.
    Stockholm University, Faculty of Science, Department of Geology and Geochemistry.
    Alexander, Larionov
    Alexander, Tebenkov
    Pease, Victoria
    Stockholm University, Faculty of Science, Department of Geology and Geochemistry.
    Andresen, Arild
    Timing of migmatization and granite genesis of the Northwestern Terrane, Svalbard2007In:  , 2007Conference paper (Other academic)
    Abstract [en]

    The pre-Devonian rocks of Svalbard can be grouped into three Caledonian terranes separated by north-south trending strike-slip faults. The paleogeography of the Southwestern and the Eastern Terranes is fairly well constrained, whereas the origin of the Northwestern Terrane (NWT) remains enigmatic. One difficulty in determining the paleogeographic origin of NWT is the complex, polyphase metamorphic history this terrane has experienced. In an attempt to understand the tectonic evolution of the NWT, a U-Pb ion microprobe study of zircons from gneisses, granitoids and migmatites from the Smerenburgfjorden Complex and Richarddalen Complex has been carried out.

    Field evidence supported by age dating indicates that a Mesoproterozoic metapelitic protolith was intruded by ca. 960 Ma granitic orthogneiss. These new ion microprobe data are comparable with ages from other parts of Northwest Svalbard, and suggest that the entire NWT is underlain by Grenvillian-age (940-1039 Ma) and older basement rocks. These units were later involved in Caledonian deformation with subsequent granite genesis and migmatization at c. 417 to 433 Ma. Inherited zircons in the Caledonian granites suggest that two different protoliths were involved in Caledonian anatexis: One sourced dominantly from Greenvillian-age basement (940-1039 Ma) and another from an older early Mesoproterozoic to Paleoproterozoic basement (1500-1900 Ma). The origin of the NWT will be discussed, in light of these results.

  • 38.
    Pettersson, Carl-Henrik
    et al.
    Stockholm University, Faculty of Science, Department of Geology and Geochemistry.
    Frei, Dirk
    Stockholm University, Faculty of Humanities, Department of Education in Languages and Language Development.
    Pease, Victoria
    Stockholm University, Faculty of Science, Department of Geology and Geochemistry. Stockholm University, Faculty of Science, Department of Geology and Geochemistry.
    Detrital zircon U-Pb ages of Late Silurian and Early Devonian sedimentary sequences from Northwestern, Svalbard, implications for regional correlations in the Arctic Caledonides2008Conference paper (Other academic)
    Abstract [en]

    In the North Atlantic region, Caledonian and Grenvillian terrains are exposed on Svalbard, Greenland, Great Britain, Canada and Scandinavia. Reconstructing the original configuration of these terrains depends partly on determining the age and provenance of the sedimentary rocks overlying the basement. Provenance investigations using detrital zircon U-Pb ages are a powerful tool to explore the palaeogeography and can yield important information how the North Atlantic region evolved through the Grenvillian and Caledonian orogenies.

    U-Pb laser ablation ICP-MS provenance study of zircons from Late Silurian and Early Devonian coarse siliciclastics of NW Svalbard indicate an east Greenland provenance. The decrease in 410-440 Ma ages and 2600-2800 Ma ages, combined with a large increase in 950-1000 Ma ages up-section suggests that sediment detritus was initially derived from exhumation of the Caledonian Orogen and subsequently from the Grenvillain Orogen.

  • 39.
    Pettersson, Carl-Henrik
    et al.
    Stockholm University, Faculty of Science, Department of Geology and Geochemistry.
    Frei, Dirk
    Pease, Victoria
    Stockholm University, Faculty of Science, Department of Geology and Geochemistry.
    U-Pb Zircon Provenance of Metasedimentary Basement of the Northwestern Terrane, Svalbard: A central East Greenland correlation2007Conference paper (Other academic)
    Abstract [en]

    Svalbard’s Caledonian and older bedrock consists of three main exotic terranes separated by north-south trending strike-slip faults. Early in the 19th century Kulling (1930, 1934) noted the striking similarity between the Neoproterozoic and Early Paleozoic sedimentary rocks from East Greenland and Svalbard’s Eastern Terrane. After this pioneering work Harland et al. (1969) documented their remarkable similarities through detailed stratigraphic correlation of Neoproterozoic and Early Paleozoic sedimentary rocks. Recent work in the Northwestern and the eastern part of the Eastern terrane shows that this metasedimentary basement has a strong resemblance to the Krummedal and Smallefjord sequences of central East Greenland, with Grenville age (sensu lato) granitoid intrusion followed by Caledonian migmatization and granite genesis. We present the first LA-ICP-MS U-Pb zircon provenance study on quartzites and mica schists from the Kongsfjorden Group of the Northwestern Terrane of Svalbard. These results indicate a strong correlation with the Krummedal of central East Greenland and help to constrain paleogeographic reconstructions of the Northwestern Terrane.

  • 40.
    Pettersson, Carl-Henrik
    et al.
    Stockholm University, Faculty of Science, Department of Geology and Geochemistry.
    Pease, Victoria
    Stockholm University, Faculty of Science, Department of Geology and Geochemistry.
    Frei, Dick
    U-Pb zircon provenance of metasedimentary basement of the Northwestern Terrane, Svalbard: Implications for the Grenvillian–Sveconorwegian orogenyand development of Rodinia2009In: Precambrian Research, ISSN 0301-9268, E-ISSN 1872-7433, Vol. 175, no 1-4, 206-220 p.Article in journal (Refereed)
    Abstract [en]

    Svalbard is pivotal for defining the northern extent of the Grenville/Sveconorwegian orogenic belt. Consequently, to constrain the origin of Svalbard’s Northwestern Terrane (NWT), detrital zircon populations from samples of the Krossfjorden Group and Smerenburgfjorden complex, northwestern Svalbard, were analyzed by U-Pb Laser ablation ICP-MS. These data indicate that the NWT’s metasedimentary basement, the Krossfjorden Group, was deposited between c. 1020-995 Ma and indicates that the Smerenburgfjorden complex may represent a migmatized and deformed part of the Krossfjorden Group. Statistically, the source area of the Krossfjorden Group can not be distinguished from other late Mesoproterozoic to early Neoproterozoic siliciclastic sequences exposed in the Caledonian orogenic belt and their detrital populations are compatible with derivation from the Eastern Grenville Province (EGP), dominated by ages coinciding with the Labradorian event (1710-1600 Ma). The diachronous tectonothermal evolution of these Meso-to Neoproterozoic metasedimentary sequences suggests deposition in a spatially linked peripheral foreland and remnant ocean basins located east of EGP, which migrated eastwards during the final suturing of Rodina. Thus, they do not represent a northern branch of the Grenvillian/Sveconorwegian Orogeny.

  • 41.
    Rantakokko, Nina E.
    et al.
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Whitehouse, Martin J.
    Stockholm University, Faculty of Science, Department of Geological Sciences. Swedish Museum of National History, Sweden; Nordic Center for Earth Evolution (NordCEE), Sweden.
    Pease, Victoria
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Windley, Brian F.
    Neoproterozoic evolution of the eastern Arabian basement based on a refined geochronology of the Marbat region, Sultanate of Oman2014In: Tectonic Evolution of the Oman Mountains / [ed] Rollinson, H. R.; Searle, M. P.; Abbasi, I. A.; AlLazki, A. I.; AlKindi, M. H., Bath: Geological Society Publishing House , 2014, Vol. 392, 107-127 p.Chapter in book (Refereed)
    Abstract [en]

    New high spatial resolution secondary ion mass spectrometry (SIMS) U-Pb zircon data from the Sadh gneiss complex and the intruding Marbat granodiorite of the Marbat region, southern Sultanate of Oman, yield Cryogenian magmatic protolith ages for gneisses ranging from c. 850 to 830 Ma. Zircon ages record a c. 815-820 Ma period of deformation and migmatization, followed by intrusion of a hornblende gabbro/diorite and the undeformed Marbat granodiorite at c. 795 Ma. Following break-up and rifting of Rodinia at c. 870 Ma, crustal growth in the Marbat region occurred via arc accretion at c. 850-790 Ma, possibly in the easternmost part of the Mozambique Ocean based on earlier cessation of accretion here compared to the Arabian-Nubian Shield. Similarity of the new zircon geochronology to peaks of detrital zircon ages in the unconformably overlying Ediacaran Marbat sandstone suggests relatively local derivation from uplifted basement for the latter.

  • 42.
    Robinson, Frank A.
    et al.
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Bonin, B.
    Pease, Victoria
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Anderson, J. L.
    A discussion on the tectonic implications of Ediacaran late- to post-orogenic A-type granite in the northeastern Arabian Shield, Saudi Arabia2017In: Tectonics, ISSN 0278-7407, E-ISSN 1944-9194, Vol. 36, no 3, 582-600 p.Article in journal (Refereed)
    Abstract [en]

    The transition from late-orogenic to post-orogenic magmatism following major orogenic episodes such as the Neoproterozoic to Cambrian East African Orogen (EAO) is an important, yet not well-understood geological event marking the cessation of subduction-controlled magmatism between buoyant lithospheric fragments. Forming the northern part of the EAO in the Arabian-Nubian Shield are three granitic suites that successively intruded the same northeastern area and post-date the 640Ma major orogenic episode: (1) 620-600Ma alkali feldspar (hypersolvous) granite with alkaline/ferroan/A-type geochemistry, (2) 599Ma granite cumulates (some garnet-bearing) with calc-alkaline/magnesian affinities, and (3) 584-566Ma alkali feldspar (hypersolvous) granite (aegirine-bearing) with a distinctive peralkaline/ferroan/A-type signature. Combining whole-rock geochemistry from the southern and northern Arabian Shield, suites 1 and 2 are suggested to be products of late-orogenic slab tear/rollback inducing asthenospheric mantle injection and lower crustal melting/fractionation toward A-type/ferroan geochemistry. Suite 3, however, is suggested to be produced by post-orogenic lithospheric delamination, which replaced the older mantle with new asthenospheric (rare earth element-enriched) mantle that ultimately becomes the thermal boundary layer of the new lithosphere. Major shear zones, such as the 620-540Ma Najd Fault System (NFS), are some of the last tectonic events recorded across the Arabian Shield. Data presented here suggest that the NFS is directly related to the late-orogenic (620-600Ma) slab tear/rollback in the northeastern Shield as it met with opposing subduction polarity in the southern Shield. Furthermore, this study infers that east and west Gondwana amalgamation interacted with opposing convergence reflected by the NFS.

  • 43. Scott, R.
    et al.
    Anderson, L.
    Pease, Victoria
    Stockholm University, Faculty of Science, Department of Geology and Geochemistry.
    Sinclair, S.
    Opening of the Amerasia Basin and its Significance for Understanding Late Palaeozoic and Mesozoic Sediment Dispersal patterns in the Arctic.2007In: AAPG (Athens) conference proceedings, 2007, 1- p.Conference paper (Other academic)
  • 44. Scott, R.
    et al.
    Howard, J.
    Guo, L.
    Schekoldin, R.
    Pease, Victoria
    Stockholm University, Faculty of Science, Department of Geology and Geochemistry.
    Offset and curvature of the Novaya Zemlya fold-and-thrust belt, Arctic Russia2010In: The Petroleum Geology Conference series, Vol. 7, 591-619 p.Article in journal (Refereed)
    Abstract [en]

    The Eastern Barents, Kara, Laptev, East Siberian seas and the western Chukchi Sea occupy a large part of the Eurasian Arctic epicontinental shelf in the Russian Arctic. Recent studies have shown that this huge region consists of over 40 sedimentary basins of variable age and genesis which are thought to bear significant undiscovered hydrocarbon resources. Important tectonic events controlling the structure and petroleum geology of the basins are the Caledonian collision and orogeny followed by Late Devonian to Early Carboniferous rifting, Late Palaeozoic Baltica–Siberia collision and Uralian orogeny, Triassic and Early Jurassic rifting, Late Jurassic to Early Cretaceous Canada Basin opening accompanied by closure of the South Anyui Ocean, the Late Mesozoic Verkhoyansk–Brookian orogeny and Cenozoic opening of the Eurasia Oceanic Basin. The majority of the sedimentary basins were formed and developed in a rift and post-rift setting and later modified through a series of structural inversions. Using available regional seismic lines correlated with borehole data, onshore geology in areas with no exploration drilling, and recent Arctic-wide magnetic, bathymetry and gravity grids, we provide more confident characterization of the regional structural elements of the Russian Arctic shelf, and constrain the timing of basin formation, structural styles, lithostratigraphy and possible hydrocarbon systems and petroleum play elements in frontier areas.

  • 45. Scott, R.
    et al.
    Pease, Victoria
    Stockholm University, Faculty of Science, Department of Geology and Geochemistry.
    Kuzmichev, A.
    Tectonic affinities in northern Russia and their implications for Amerasia Basin spreading models.2007In: V International Conference of Arctic Margins Abstract Volume, NGF,, 2007, 69- p.Conference paper (Other academic)
  • 46. Sokolov, S. D.
    et al.
    Ledneva, G. V.
    Pease, Victoria L.
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    New Data on the Age and Genesis of Igneous Rocks in the Kolyuchinskaya Guba (Eastern Chukotka)2009In: Doklady Earth Sciences, ISSN 1028-334X, E-ISSN 1531-8354, Vol. 425, no 2, 384-388 p.Article in journal (Refereed)
  • 47. Whitehouse, M. J.
    et al.
    Pease, Victoria
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Al-Khirbash, S.
    Neoproterozoic crustal growth at the margin of the East Gondwana continent - age and isotopic constraints from the easternmost inliers of Oman2016In: International Geology Review, ISSN 0020-6814, E-ISSN 1938-2839, Vol. 58, no 16, 2046-2064 p.Article in journal (Refereed)
    Abstract [en]

    The Jebel Ja'alan and Qalhat inliers of Oman represent the easternmost exposures in the Arabian peninsula of the Neoproterozoic basement associated with the East African Orogen (EAO) and the assembly of East and West Gondwana. These inliers expose tonalitic gneisses and metasediments intruded by granodiorites and granites of the Ja'alan batholith. Zircons from the gneisses yield U-Pb SIMS ages of ca. 900-880Ma, which are interpreted as crystallization ages. These represent the oldest magmatic events associated with the closure of the Mozambique Ocean reported to date. Zircon of this age is also the dominant component in the metasediments. The Ja'alan batholith yields ages of ca. 840-825Ma. Nd isotopes indicate that both the gneisses and the batholith range from juvenile to slightly more evolved, with epsilon(Nd)(t) of +6 to +1.5 interpreted to reflect variable contamination by older, evolved continental material; this is also indicated by >900Ma detrital zircon from the metasediments. The Nd data also contrast with the uniformly juvenile signature of younger, ca. 840Ma, rocks of the Marbat region of southern Oman that lie structurally to the west. The Ja'alan and Qalhat inliers thus document eastward increasing age and continental influence, consistent with the progressive development of arc rocks onto the western margin of East Gondwana, although the location and nature of the eastern continental block remain elusive.

  • 48.
    Wohlgemuth-Uberwasser, Cora C.
    et al.
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Söderlund, Ulf
    Pease, Victoria
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Nilsson, Mimmi K. M.
    Quadrupole LA-ICP-MS U-PB geochronology of baddeleyite single crystals2015In: Journal of Analytical Atomic Spectrometry, ISSN 0267-9477, E-ISSN 1364-5544, Vol. 30, no 5, 1191-1196 p.Article in journal (Refereed)
    Abstract [en]

    We present a straightforward method for accurate and precise U/Pb dating of baddeleyite using quadrupole LA-ICP-MS. To establish the validity of our ICP-MS data we used FC-4b baddeleyite from the Duluth complex as external standard, whereas baddeleyite from the Phalaborwa (South Africa) and the Sorkka (SW Finland) intrusions were treated as unknowns. The analytical protocol includes the use of a matrix matched standard, which allows for an accurate downhole-fractionation and laser-induced interelement fractionation correction. The quadrupole ICP-MS results for the Phalaborwa and Sorkka samples analyzed are accurate within error of the published ID-TIMS U/Pb ages and with a precision of 0.3–0.7% (2σ) from concordia ages of ten to twenty analyses per sample. No orientation effects were observed.

  • 49.
    Wohlgemuth-Ueberwasser, Cora C.
    et al.
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Tegner, Christian
    Pease, Victoria
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    LA-Q-ICP-MS apatite U/Pb geochronology using common Pb in plagioclase: Examples from layered mafic intrusions2017In: American Mineralogist, ISSN 0003-004X, E-ISSN 1945-3027, Vol. 102, no 3, 571-579 p.Article in journal (Refereed)
    Abstract [en]

    Apatite geochronology is a versatile method for providing medium temperature history constraints of magmatic and metamorphic rocks. The LA-ICP-MS technique is widely applied to U/Pb geochronology using various minerals. Apatite U/Pb geochronology, in contrast to e.g., zircon, is compromised by variable amounts of common Pb incorporated into the crystal during growth. Magmatic apatite often shows a sufficient spread in data to obtain a precise and accurate lower intercept age. If this is not the case, the initial Pb isotopic composition needs to be estimated to obtain accurate and precise age information from apatite. Two approaches are common, one being the estimation of common Pb from a Pb evolution model and the other being the measurement of a coexisting mineral phase that tends to incorporate Pb but not U, e.g.,feldspar. Most recent studies applying LA-ICP-MS to the analysis of Pb isotopes in feldspar utilize either multicollector or magnetic sector mass spectrometers. In this study we first evaluate the application of quadrupole mass spectrometry for apatite U/Pb geochronology combined with Pb isotopic measurements in feldspar and compare the results with modeled initial Pb isotopic compositions. The resulting age information is accurate and precise despite using plagioclase rather than K-feldspar, as is normally used, to define initial Pb isotope compositions. We apply this method to apatite-bearing gabbroic rocks from layered intrusions (Bushveld, Bjerkreim-Sokndal, Hasvik, and Skaergaard) ranging in age from ca. 2 Ga to ca. 55 Ma and generate metamorphic/cooling ages generally consistent with the known geologic history of these intrusions.

  • 50. Yaseen, Najel
    et al.
    Pease, Victoria
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Jarrar, Ghaleb H.
    Whitehouse, Martin
    U-Pb detrital zircon provenance of the Saramuj Conglomerate, Jordan, and implications for the Neoproterozoic evolution of the Red Sea region2013In: Precambrian Research, ISSN 0301-9268, E-ISSN 1872-7433, Vol. 239, 6-23 p.Article in journal (Refereed)
    Abstract [en]

    The latest stage in the evolution of the northernmost Arabian-Nubian Shield is characterized by the development of volcano-sedimentary successions. In Jordan the Saramuj Conglomerate Formation is considered to be one of these post-tectonic basins. It is polymict and poorly sorted with wide range of clast compositions, roundness and size. We present the first SIMS U-Pb dating of detrital zircons from two sandstone samples representative for the conglomerate matrix and of four clasts from the Saramuj Conglomerate for provenance and age determinations. The relative probability curve for the matrix samples indicates a major contribution (85%) from c. 600 to 650 Ma, subclusters at 624 and 640 Ma, a minor source from 700 to 750 Ma, and a clear gap between 650 and 700 Ma. These ages are consistent with those obtained from andesitic, rhyodacitic, granitic and gneiss clasts (624, 642,650 and 734 Ma respectively). In contrast to the adjacent volcano-sedimentary successions in the Elat area, Sinai and the Eastern Desert, no ages older than 750 Ma were found. The good match between the known ages of the nearby exposed basement with the matrix ages and the immature nature of the sediments implies that the principal input was locally derived erosional detritus. The age of the youngest 10 detrital zircons at C. 615 Ma represents the maximum age of deposition, which is consistent with the stratigraphic position of the Saramuj Conglomerate. Clast ages of 642 Ma and 650 Ma are interpreted as evidence for a magmatic source that has not been recognized in SW Jordan. This study implies that the volcano-sedimentary successions in the northernmost Arabian-Nubian shield may be broadly coeval but have distinct provenance and therefore evolved as isolated basins. Furthermore, U-Pb zircon provenance analysis allows us to recognize igneous products that are no longer preserved and/or exposed in the region.

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