Clay Mineral Composition of Beaufort Sea Sediments, Arctic Ocean: ABSTRACT

Abstract

Clay mineral composition of the less than 2- and 4-µ size fractions of Beaufort Sea sediments was analyzed by X-ray diffraction techniques. In all except one sample illite is the predominant (51.58-89.46%) clay mineral, kaolinite is present in significant amounts (10.54-42.82%), and chlorite is almost absent. These observations are interesting because of the generally accepted view that kaolinite is a low latitude clay mineral and chlorite a high latitude one. The presence of kaolinite in the Beaufort Sea is explained by the polycyclic nature of its sediments which have their primary source in kaolinite-rich Mesozoic sedimentary rocks of the North Slope. This explanation is indicated by the large (36.79%) amount of kaolinite in the Colville, the largest river dra ning from those rocks to the Beaufort Sea. The shore ice, presumably deriving its entrapped sediment from the hinterland, also contains large amounts of kaolinite. It is concluded that a part of this kaolinite is ice rafted to the deeper Beaufort Sea. The use of clay minerals as a key for the inference of paleoclimates of source rocks on the basis of earlier generalizations may lead to erroneous conclusions, as attested by the present results. For a correct interpretation of paleoclimates it is suggested that clay-mineral data be substantiated by additional data, such as paleontologic and chemical. Preliminary studies suggest that most illite of Beaufort Sea has formed by illitization of an illite-montmorillonite (?) type mineral. End_of_Article - Last_Page 355------------