The chemical index of alteration in Permo-Carboniferous strata in North China as an indicator of environmental and climate change throughout the late Paleozoic Ice Age

Comparison of chemical index of alteration (CIA) values and estimated land surface temperatures (LSTs) from upper Carboniferous-Permian successions in low paleolatitude North China and middle- to high-paleolatitude successions of Gondwana facilitates reconstruction of global climate changes during the late Paleozoic Ice Age. Four synchronous excursions between the North China and Gondwana Basins toward lower CIA and LSTs are recognized and interpreted as four cooling events, respectively. Two severe cooling events occurred around 300 Ma and 287 Ma, respectively, with large decreases in global temperatures (mostly >5 °C), while another two less-pronounced cooling events at 297.5 Ma and 295 Ma with global temperature drops of