Multi‐approach characterization of shallow‐water carbonates off Minamitorishima and their depositional settings/history

Sedimentological, geochemical, and chronological analyses were carried out on 18 carbonate rock samples collected at depths of 938, 1085, 3354 m the western slope Minamitorishima (Marcus Island), which is located near margin Pacific Plate. Four groups rocks distinguished: a mollusk-rich limestone, coral-rich dolomite, foraminiferal-nannofossil packstone, phosphatized mudstone/wackestone. The limestone characterized by dominance bivalves (including rudists) gastropod shells. Strontium isotope ratios (87Sr/86Sr) Mesorbitolina ex gr. texana (a large benthic foraminifer) indicate that shallow-water carbonates deposited during late Aptian–early Albian (ca. 123–111 Ma). dolomite abundant scleractinian corals nongeniculate coralline algae associated with encrusting acervulinid foraminifers. biotic composition similar to Oligocene–Pleistocene reported from other seamounts in northwestern Pacific. Geochemical data show dolomitized 9.5–6.8 Ma (Tortonian–Messinian) normal seawater was most likely parent fluid. packstone semi-consolidated ooze Pleistocene (0.99–0.45 mudstone/wackestone marked absence macrofossils presence traces planktic Although its depositional age not constrained, Sr phosphatization occurred 33.2–28.9 Ma. After deposition Cretaceous carbonates, including drowned top covered pelagic cap, represented Eocene–early Oligocene volcanism (40.2–33.2 Ma) caused episodic uplift returned environment. early coral reefs flourished this island. reef Tortonian–Messinian.