Main content area

Carbonate thermoluminescence and its implication for marine productivity change during the Permian-Triassic transition

Qiu, Zhipu, Song, Haijun, Hu, Chaoyong, Wignall, Paul B., Song, Huyue
Palaeogeography, palaeoclimatology, palaeoecology 2019 v.526 pp. 72-79
Phanerozoic eon, carbonates, extinction, hypoxia, manganese, organic matter, primary productivity, thermoluminescence, China
The Permian-Triassic (P-Tr) crisis was the largest mass extinction of the Phanerozoic and eliminated over 90% of marine species. However, the nature of marine productivity changes during the crisis is a matter of on-going debate. Here, thermoluminescence (TL) measurements from 144 bulk carbonate samples from Meishan (South China) show two levels of variation in TL peak intensities at ~270 °C. The first-order variation is characterized by a rapid, nearly three-fold increase. A secondary variation is interpreted to record periodic fluctuations on a Milankovitch scale (~20-kyr rhythm). The periodic variations of TL are negatively correlated with Mn concentrations, suggesting primary productivity is a key factor controlling the TL peak intensity by photo-reduction of particulate Mn in the presence of organic matter. Therefore, the periodic fluctuations of TL were likely controlled by primary productivity changes on orbital timescales. A significant rise of TL peak intensities across the P-Tr boundary represents the rapid increase of dissolved Mn associated with enhanced marine productivity and/or oceanic anoxia.