Publikationsdatum:
2018-09-03
Beschreibung:
On its way to the surface, the Siberian Traps magma created a complex sub-volcanic plumbing system. This resulted in a large-scale sill emplacement within the Tunguska Basin and subsequent release of sediment-derived volatiles during contact metamorphism. The distribution of sills and the released sediment-stored gas volume is, however, poorly constrained. In this paper, results from a study of nearly 300 deep boreholes intersecting sills are presented. The results show that sills with thicknesses above 100 m are abundant throughout the upper part of the sedimentary succession. A high proportion of the sills was emplaced within the Cambrian evaporites with average thicknesses in the 115–130 m range and a maximum thickness of 428 m. Thermal modelling of the cooling of the sills shows that the contact metamorphic aureoles are capable of generating 52–80 tonnes of CO 2 m −2 with contributions from both marine and terrestrial carbon. When up-scaling these borehole results, an area of 12–19 000 km 2 is required to generate 1000 Gt CO 2 . This represents only 0.7–1.2% of the total area in the Tunguska Basin affected by sills, emphasizing the importance of metamorphic gas generation in the Siberian Traps. These results strengthen the hypothesis of a sub-volcanic trigger and driver for the environmental perturbations during the End-Permian crisis. This article is part of a discussion meeting issue ‘Hyperthermals: rapid and extreme global warming in our geological past’.
Print ISSN:
1364-503X
Digitale ISSN:
1471-2962
Thema:
Mathematik
,
Physik
,
Technik allgemein
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