DOI: 10.1016/j.palaeo.2015.07.007
论文题名: The Early Cretaceous Barents Sea Sill Complex: Distribution, 40Ar/39Ar geochronology, and implications for carbon gas formation
作者: Polteau S. ; Hendriks B.W.H. ; Planke S. ; Ganerød M. ; Corfu F. ; Faleide J.I. ; Midtkandal I. ; Svensen H.S. ; Myklebust R.
刊名: Palaeogeography, Palaeoclimatology, Palaeoecology
ISSN: 0031-0182
出版年: 2016
卷: 441 起始页码: 83
结束页码: 95
语种: 英语
英文关键词: 40Ar/39 Ar chronology
; Anoxic event
; Barents Sea
; Cretaceous paleoclimate
; HALIP
; Large igneous provinces
英文摘要: Mafic igneous rocks of Cretaceous age (80-130 Ma) scattered around the Arctic Ocean are commonly referred to as the High Arctic Large Igneous Province (HALIP). We have mapped out the distribution of HALIP igneous rocks in the Barents Sea region over the past decade based on integrated seismic-gravity-magnetic interpretation, field work, review of publications, and analyses of new and vintage borehole and field samples. The mapping reveals abundant igneous rocks in the northern and eastern Barents Sea covering an area of ~900,000km2 with a conservative volume estimate of 100,000 to 200,000km3 of intrusions. The igneous province is dominated by sheet intrusions injected into Triassic and Permian sedimentary rocks. Hydrothermal vent complexes are rare, and only two potential vent complexes have been identified on seismic data in the eastern Barents Sea. We have further done extensive radiometric dating of the igneous samples in the Barents Sea region. New 40Ar/39Ar dating of thirteen samples from Svalbard reveal ages of crystallization and alteration. The large age span (60-140 Ma for the raw ages) is likely due to partial or complete overprint of the K/Ar system in plagioclase, and the age of the magma emplacement is better represented by U/Pb TIMS ages. Only one of our 40Ar/39Ar analyses of plagioclase yielded a statistically valid age that is in line with the recently published U/Pb TIMS ages of 122-125Ma. The new data clearly document that relying on published data from the K/Ar system can lead to erroneous conclusions on the age of crystallization in this province without a careful use of additional 40Ar/39Ar degassing data (i.e., K/Ca). We propose that the magmatism on Svalbard and Franz Josef Land represents a distinct magmatic event near the Barremian/Aptian boundary (125 Ma) in the Barents Sea. This Early Cretaceous Barents Sea magmatism resulted in the formation of the BSSC (Barents Sea Sill Complex). BSSC age rocks are also present in Arctic Canada (Sverdrup Basin) and on Bennett Island (New Siberia Islands). The massive injection of hot magma into potentially organic-rich sediments in the eastern and northern Barents Basin caused rapid organic matter maturation and formation of thermogenic gas and oil in contact aureoles. We estimate that up to 20,000 Gt of carbon were potentially mobilized, corresponding to 175 trillion barrels of oil equivalent. The production rates and fate of the carbon gases are uncertain. However, we speculate that rapid release of aureole greenhouse gases (methane) may have triggered the Oceanic Anoxic Event 1a (OAE1a) and the associated negative δ13C excursion in the Early Aptian. Some of the methane may also be trapped in the vast hydrocarbon gas accumulations found in the east Barents Basin. © 2015 Elsevier B.V. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/68672
Appears in Collections: 过去全球变化的重建
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作者单位: Volcanic Basin Petroleum Research, Oslo Innovation Center, Gaustadalléen 21, Oslo, Norway; Geological Survey of Norway, Postboks 6315 Sluppen, Trondheim, Norway; The Center for Earth Evolution and Dynamics, University of Oslo, PO Box 1028 Blindern, Oslo, Norway; Department of Geosciences, University of Oslo, PO Box 1047, Blindern, Oslo, Norway; TGS, Lensmannslia 4, Asker, Norway; Statoil Forskningssenter, Arkitekt Ebbells veg 10, Ranheim, Norway
Recommended Citation:
Polteau S.,Hendriks B.W.H.,Planke S.,et al. The Early Cretaceous Barents Sea Sill Complex: Distribution, 40Ar/39Ar geochronology, and implications for carbon gas formation[J]. Palaeogeography, Palaeoclimatology, Palaeoecology,2016-01-01,441