Hydrogen and Oxygen Isotopic Compositions of Sedimentary Clay in the Sea Region off the Western Antarctic Peninsula and Their Material Sources

In the geochemical study of sedimentation, hydrogen and oxygen isotope data are useful for a discussionon formation conditions and material sources of sediments. Hydrogen and oxygen isotope analyses were madeon clays separated from the sea-floor surface sediments at 9 stations in the western sea region of the AntarcticPeninsula. On the basis of these isotopic data and the clay mineral components and by use of statistical dia-grams, it may be concluded that the clay fraction in this sea region is composed mainly of terrigenous detritus:i.e. it was formed by surface weathering or supergene alteration of the rocks from the terrigenous region in thepeninsular in the presence of meteoric water. However, at least a part of montmorillonite is a marine authigenicmineral formed by alteration of submarine eruptive materials or terrigenous pyroclasts in the presence of seawater. The above result is consistent with the idea derived from the study of clay mineralogy.

Hydrogen and Oxygen Isotopic Compositions of Sedimentary Clay in the Sea Region off the Western Antarctic Peninsula and Their Material Sources

Abstract In the geochemical study of sedimentation, hydrogen and oxygen isotope data are useful for a discussion on formation conditions and material sources of sediments. Hydrogen and oxygen isotope analyses were made on clays separated from the sea-floor surface sediments at 9 stations in the western sea region of the Antarctic Peninsula. On the basis of these isotopic data and the clay mineral components and by use of statistical diagrams, it may be concluded that the clay fraction in this sea region is composed mainly of terrigenous detritus; i.e. it was formed by surface weathering or supergene alteration of the rocks from the terrigenous region in the peninsular in the presence of meteoric water. However, at least a part of montmorillonite is a marine authigenic mineral formed by alteration of submarine eruptive materials or terrigenous pyroclasts in the presence of sea water. The above result is consistent with the idea derived from the study of clay mineralogy.