Global change and manganese deposition at the Cenomanian-Turonian boundary

Author(s): Dickens, Gerald R.; Owen, Robert M.
Author Affiliation(s): Primary:
University of Michigan, Department of Geological Sciences, Ann Arbor, MI, United States
Volume Title: Marine Georesources & Geotechnology
Source: Marine Georesources & Geotechnology, 11(1), p.27-43. Publisher: Taylor & Francis, London, United States. ISSN: 1064-119X
Note: In English. 55 refs.; illus. incl. 2 tables, geol. sketch maps
Summary: Several of the world's large stratiform Mn deposits formed in shallow water environments at the CTB (approx 92 m.y.). Earth history at this time is also characterized by increased tectonism, the highest Mesozoic-Cainozoic sea-level stand, and widespread reducing conditions in the oceans. Evidence is presented for a causal relationship between these global-scale phenomena. A high resolution geochemical analysis of pelagic sediments from two sites on the Exmouth plateau (off NW Australia) indicates significant Mn depletion and reducing conditions coincident with deposit formation. It is suggested that the coupling between deep water Mn depletions and shallow water Mn enrichments involved the sequestering of hydrothermally derived Mn within expanded oxygen minimum zones via diagenetic remobilization and/or direct entrapment of hydrothermal effluents, and its subsequent deposition on shelf substrates at the top of a redoxcline.
Year of Publication: 1993
Research Program: ODP Ocean Drilling Program
Key Words: 27 Economic Geology, Metals; Cenomanian; Cretaceous; Exmouth Plateau; Global change; Hydrothermal alteration; Hydrothermal processes; Indian Ocean; Leg 122; Manganese ores; Mesozoic; Metal ores; Metasomatism; Mineral deposits, genesis; ODP Site 762; ODP Site 763; Ocean Drilling Program; Sea-level changes; Stratigraphic boundary; Transgression; Turonian; Upper Cretaceous
Coordinates: S195315 S195314 E1121515 E1121514
S213000 S203500 E1121515 E1121514
Record ID: 1993022648
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United Kingdom, Twickenham, United Kingdom