Ribbon rocks are characterized by an alternation of millimeter-to centimeter-thick limestone and argillaceous deposits (marlstone or shale). The sedimentary processes and diagenetic characteristics of ribbon rocks might be critical to the formation of limestone conglomerates. According to detailed field measurement and laboratory analyses (thin section observation and XRD analysis), four types of ribbon rocks are classified, i.e., limestone and marlstone couplet (L-M), limestone and shale couplet (L-S), thin-bedded lime mudstone (Ltb), and laminated limestone and marlstone couplet (Cl). These ribbon rocks were mostly deposited in low-energy subtidal environments (below fair-weather wave base). Ribbon rocks exhibit various subtle deformation structures such as intrastratal cracks and "boudin" structures. Differential cementation of carbonate and argillaceous layers during early diagenesis is a prerequisite condition for the deformation of ribbon rock under compaction. Ribbon rocks would be deformed into limestone conglomerates under differential compaction that might be triggered by external forces such as storm and earthquake. ribbon rock, cracks, "boudin" structure, early diagenesis, pseudoconglomerate, Furongian, Shandong Province Citation:Chen J T, Han Z Z, Zhang X L, et al. Early diagenetic deformation structures of the Furongian ribbon rocks in Shandong Province of China-A new perspective of the genesis of limestone conglomerates.
Significance
Massive carbon (C) release with abrupt warming has occurred repeatedly during greenhouse states, and these events have driven episodes of ocean deoxygenation and extinction. Records from these paleo events, coupled with biogeochemical modeling, provide clear evidence that with continued warming, the modern oceans will experience substantial deoxygenation. There are, however, few constraints from the geologic record on the effects of rapid warming under icehouse conditions. We document a C-cycle perturbation that occurred under an Earth system state experiencing recurrent glaciation. A suite of proxies suggests increased seafloor anoxia during this event in step with abrupt increase in CO
2
partial pressure and a biodiversity nadir. Warming-mediated increases in marine anoxia may be more pronounced in a glaciated versus unglaciated climate state.
The late Paleozoic was a dynamic and crucial time in the evolution of the Earth system. It is characterized by the assembly of supercontinent Pangea (Metcalfe, 2013;Stampfli et al., 2013), superplume activities embodied by the Skagerrak-Centered large igneous province (LIP),
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