The Early Cretaceous Barents Sea Sill Complex: Distribution, 40Ar/39Ar geochronology, and implications for carbon gas formation

摘要: Abstract Mafic igneous rocks of Cretaceous age (80–130 Ma) scattered around the Arctic Ocean are commonly referred to as High Large Igneous Province (HALIP). We have mapped out distribution HALIP in Barents Sea region over past decade based on integrated seismic–gravity–magnetic interpretation, field work, review publications, and analyses new vintage borehole samples. The mapping reveals abundant northern eastern covering an area ~ 900,000 km2 with a conservative volume estimate 100,000 200,000 km3 intrusions. province is dominated by sheet intrusions injected into Triassic Permian sedimentary rocks. Hydrothermal vent complexes rare, only two potential been identified seismic data Sea. further done extensive radiometric dating samples region. New 40Ar/39Ar thirteen from Svalbard reveal ages crystallization alteration. large span (60–140 Ma for raw ages) likely due partial or complete overprint K/Ar system plagioclase, magma emplacement better represented U/Pb TIMS ages. Only one our plagioclase yielded statistically valid that line recently published 122–125 Ma. clearly document relying can lead erroneous conclusions this without careful use additional degassing (i.e., K/Ca). propose magmatism Franz Josef Land represents distinct magmatic event near Barremian/Aptian boundary (125 Ma) This Early resulted formation BSSC (Barents Sill Complex). also present Canada (Sverdrup Basin) Bennett Island (New Siberia Islands). massive injection hot potentially organic-rich sediments Basin caused rapid organic matter maturation thermogenic gas oil contact aureoles. up 20,000 Gt carbon were mobilized, corresponding 175 trillion barrels equivalent. production rates fate gases uncertain. However, we speculate release aureole greenhouse (methane) may triggered Oceanic Anoxic Event 1a (OAE1a) associated negative δ13C excursion Aptian. Some methane be trapped vast hydrocarbon accumulations found east Basin.