Sedimentary Characteristics and Controls of Multiple Factors on Organic‐Enrichment of the Lower Cambrian Yuertusi Formation in the Tarim Basin, Northwest China

ABSTRACT The Early Cambrian was a crucial transition for Earth's environment and life evolution. The Early Cambrian Yuertusi Formation black shale in the Tarim Basin, a typical organic‐rich black rock series, records regional sedimentary and paleo‐oceanographic information. Integrating outcrop, logging, core, seismic and litho‐geochemical data, this study documents the Yuertusi Formation's sedimentary features and organic‐rich deposit controls. Comprising lower black shale and upper carbonate, it divides into three sequences (Sq1–3). Three sedimentary facies (outer ramp, mid ramp, and inner ramp) formed in a ramp setting. Geochemical analysis shows the outer ramp had higher paleoproductivity. Oxygen isotopes and siliceous rock lithofacies suggest hydrothermal activities were in the outer ramp during Sq1. Cross‐plots and shale phosphorus indicate upwellings were active in mid‐outer ramps during Sq1–3, stronger in the mid ramp. Redox proxies show outer ramp Sq1 organic‐rich shales were anoxic, mid ramp Sq2–3 organic‐lean carbonates were oxic. Terrigenous influx (Al, Ti) didn’t correlate with TOC. In summary, the most organic‐rich deposits (TOC > 5%) in the outer ramp along the northern basin margin were controlled by hydrothermal‐induced high productivity and anoxic preservation, with siliceous, phosphate rocks and abundant trace elements.