Palygorskite Clays in Marine Sediments: Records of Extreme Climate.
Résumé
Palygorskite clay is a natural enrichment of the minerals palygorskite and sepiolite. These magnesium-bearing, fibrous clay minerals are rare and inhomogeneously distributed, except in arid-climate soils and lacustrine deposits, where they are common (Callen, 1984; Millot, 1970; Singer, 1984, 1989; and references within this volume). Palygorskite clay is often associated with smectite clay, with which it shares several beneficial sorptive, rheologic and catalytic properties (Gala 'n, 1996). Current palygorskite clay production is almost entirely provided from lacustrine or lagoonal deposits that are rarely older than of Miocene age (25 Ma). These deposits have been intensively studied in recent years. Other occurrences, notably those formed in the early Eocene ( 55-49Ma)andinthemiddle to late Cretaceous ( 100-65 Ma) times, have received much less attention. Therefore, the focus of this study is on palygorskite clays in deep-marine sediments of mid-Cretaceous to early Eocene age from Atlantic Ocean drill cores, originating from the Deep-Sea Drilling Project (DSDP) and the Ocean Drilling Program (ODP). The data are regarded in the context of the physicochemical conditions of the deep ocean during these time periods. We propose that palygorskite clays were formed authigenically, in relation to (WSBW) circulation on the seafloor.