Clay mineralogy and sedimentary environments of Eureka Sound Formation, Ellesmere Island Canadian Arctic Archipelago
Abstract
Eureka Sound Formation is composed mainly of shallow marine to brackish water deltaic sediments. The sequence ranges from three thousand to four thousand meters in thickness and is exposed throughout the Canadian Arctic. This study was conducted at Strathcona Fiord located on west central part of Ellesmere Island. The clay minerals were examined and the clay mineral berthierine was found to be the major constituent of clays in the mudstones and siltstones. Berthierine, formerly called Chamosite, is an iron rich clay with kaolinite type structure and is believed to have been formed under warm humid conditions with high PH. Berthierine has been found as pellets in recent sediments, but in the Eureka Sound Formation berthierine occurs as a homogeneous mixture. X-ray diffraction studies of the mineral show spacing of 7 A$\sp\circ$, 4.6 A$\sp\circ$, and 3.5 A$\sp\circ$ which collapse on heating at 450 degrees C for about two hours. A chlorite phase exhibits a 14 A$\sp\circ$ peak which persists up to 600 degree C and become slightly sharper at 500 degrees C. Other clay minerals present are illite and smectite. Petrographic analysis of the coarser sand grains reveals that the quartz grains have been partly or fully replaced by calcite. This type of relationship is also indicative of the high PH conditions during deposition. The presence of bertherine and other field evidence e.g. sedimentary structures, presence of carbonaceous material and biogenic structures indicate that the Eureka Sound Formation was deposited in brackish deltaic conditions.
Degree
Ph.D.
Advisors
Zinsmeister, Purdue University.
Subject Area
Geochemistry|Biogeochemistry
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