Publication Date:
2021-02-08
Description:
The end-Triassic is characterized by one of the largest mass extinctions in the Phanerozoic,
coinciding with major carbon cycle perturbations and global warming. It has been suggested that
the environmental crisis is linked to widespread sill intrusions during magmatism associated with
the Central Atlantic Magmatic Province (CAMP). Sub-volcanic sills are abundant in two of the largest
onshore sedimentary basins in Brazil, the Amazonas and Solimões basins, where they comprise up
to 20% of the stratigraphy. These basins contain extensive deposits of carbonate and evaporite, in
addition to organic-rich shales and major hydrocarbon reservoirs. Here we show that large scale volatile
generation followed sill emplacement in these lithologies. Thermal modeling demonstrates that
contact metamorphism in the two basins could have generated 88,000 Gt CO2. In order to constrain
the timing of gas generation, zircon from two sills has been dated by the U-Pb CA-ID-TIMS method,
resulting in 206Pb/238U dates of 201.477 ± 0.062 Ma and 201.470 ± 0.089 Ma. Our findings demonstrate
synchronicity between the intrusive phase and the end-Triassic mass extinction, and provide a
quantified degassing scenario for one of the most dramatic time periods in the history of Earth.
Type:
Article
,
PeerReviewed
Format:
text
Permalink
