Coupled Geomechanical and Thermodynamic Controls on Global Distribution and Morphology of Gas Hydrate in Clay‐Rich Marine Sediments

Abstract ∼90% of gas hydrates occur as pore‐filling or fracture‐filling morphology in clay‐rich marine sediments. Their dissociation releases gas with distinct environmental fates interacting with climate change. A well‐constrained model of hydrate distribution with different morphologies is urgently needed. We present a novel one based on drilling data worldwide. We identified a geomechanics‐controlled critical depth, typically several hundred meters below the seafloor, which limits the maximum occurrence depth of fracture‐filling hydrates. This relative positioning of critical depth and bottom of the gas hydrate stability zone (BGHSZ) determines hydrate distribution with various morphologies: pore‐filling hydrates develop and predominate below critical depth only when critical depth lies above BGHSZ, while only fracture‐filling hydrates occur above BGHSZ when critical depth exceeds BGHSZ. Critical depth increases with higher clay‐sized fractions or water depths, causing varying hydrate morphologies at specific depths along continental margins. This model is essential for evaluating hydrates' roles in global carbon cycle.