Lacustrine organic carbon burial in deep time: Perspectives from major geologic events and tectonic-climatic-ecological coupling

Organic carbon (OC) burial is a critical process regulating the global carbon cycle and climate system. However, compared to well-studied marine systems, the role and mechanisms of lacustrine OC burial in deep time remain poorly constrained. Despite covering an area only 1/80th that of the oceans, modern lakes contribute 10–50% of the global OC burial, highlighting their exceptional sequestration efficiency. This review synthesizes OC burial records from typical deep-time lacustrine shales, revealing that the geological-scale transition in OC burial capacity was driven by the evolution of lake ecosystems from "dead" and "starved" lakes to "ecologically primary" and "prosperous" ones. Based on the "productivity, preservation, and dilution" ternary equilibrium theory, we evaluate the multi-factor composite controls on the OC burial process, including tectonics, climate, hydro-ecological conditions, volcanic–hydrothermal activities, and marine transgressions. Our findings show that efficient OC burial results from the synergistic coupling of tectonic–climatic–ecological systems. Notably, nutrients from volcanic and hydrothermal activities were crucial for overcoming adverse climatic or ecological conditions—particularly during the "ecologically primary lakes" stage before the Late Paleozoic—thereby enabling effective OC sequestration. Finally, we propose five primary mechanisms for large-scale lacustrine OC burial: (1) volcanic–hydrothermal driven, (2) climate–volcanic activities coupling, (3) climate–basin scale coupling, (4) climate–transgressions coupling, and (5) tectonic–climate coupling. This synthesis not only offers a new perspective from lake records for understanding deep-time Earth's sphere interactions and carbon cycling but also establishes a geological-historical framework for predicting the response of lacustrine carbon reservoirs to future climate change.