Protracted formation of nodular cherts in marine platform: new insights from the Middle Permian Chihsian carbonate successions, South China

Episodic magmatism across the Permian-Triassic Crisis Boundary and its effects on underlying source rocks: records from conodont-based high-resolution geochemical proxies in marine carbonate successions, South China

“…Among these global events, the volcanism related to basalt oodings has widely been recognized as the fundamental role for causing the EPME and slackened biota recovery because it had been dynamic for a long interval, i.e., lasting from the Guadalupian-Lopingian boundary (~ 260 Ma, predating the EPME by ~ 8 myr) to middle Triassic (~ 247 Ma) (Renne et al, 1995;Kamo et al, 2003;Chen, 2015;Joachimski et al, 2019). Meanwhile, hydrocarbon source rocks and associated petroleum systems occurred worldwide in later-Permian marine carbonate successions, such as the Krishna Godavari Basin, the central Persian Gulf, the Sichuan Basin, and the South China regions discussed in the current study (Liu et al, 2016(Liu et al, , 2022Nazemi et al,2019;Kala et al, 2021). These hydrocarbons were closely associated with the end-Permian magmatism temporally and spatially.…”

“…3f). More detailed lithologic and mineralogical features of Chihsian carbonates were described by Liu et al (2022). This stratigraphy can be correlated to international stratigraphic system, as shown in Fig.…”

“…However, the exact geological time should be determined by highprecision geochronology). Secondly, the dolomites from "quartz-dolomite assemblage" and micrites con ned within cherty nodules was regarded as occurring simultaneously in previous study (see detailed illustrations by Liu et al, 2022). However, the two minerals should be formed successively according to our high-resolution 87 Sr/ 86 Sr ratios, i.e., the dolomites and the micrites in cherts being formed corresponding to magmatism episode-1 and episode-2, respectively (Figs.…”

“…This correlation has con rmed the previous inference proposing that massive hydrothermal uids were involved in formation of Chihsian source rocks. However, the forming pattern proposed by Liu et al (2022) should be revised in the following aspects according to our evidences. Firstly, the involvement of hydrothermal uids did not occur at syn-depositional, but at post-depositional stage before solidi cation (i.e., linking to EPME and relevant magmatism, ~ 251 Ma.…”

Dolomite Origins of the Carbonate Successions From the Chihsia Formation, South China: A Case Study From the Pingdingshan Section

“…The deposition of this area was controlled by the Jiangnan Faulting event, developing marine sedimentation from the Sinian to the Triassic with total strata thickness of ~14,000 m. The Pingdingshan section is outcropped at a syncline structure which was formed due to an ancient continuous folding movement characterized by a northeastern trend. From northeast to southwest, the Yufudacun syncline, the Ma'anshan monocline, the Fenghuangshan anticline, the Pingdingshan syncline, and the Majiashan monocline are sequentially outcropped (Figure 1A; Liu et al, 2022). The Chihsia Formation, characterized by wide occurrence and stable distribution with a thickness of 100~200 m, is an important regional marine hydrocarbon source rock in South China and the most representative carbonate source rock in the Lower Yangtze region.…”