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Marine Magnetic Survey of Kachemak Bay, Alaska

David B. Prindle

Kachemak Bay in south-central Alaska is approximately 60 km long and 20 km wide at the mouth. Geologically, Kachemak Bay marks the boundary between the Mesozoic rocks of the Kenai Mountains and the low-lying Tertiary sediments of the northwestern part of the Kenai Peninsula. It is believed that the Border Ranges fault traverses the bay, although the fault's exact location is not known. In the summer of 1981, a marine magnetic survey was conducted to attempt to locate the fault and/or other geologic boundaries. The magnetic data indicate that a fault, presumed to be the Border Ranges fault, traverses the bay between Seldovia and Homer. The location of what is inferred to be the contact between the Mesozoic and Tertiary rocks can also be seen in the magnetic data. The data lso suggest the existence of a magnetic (ultramafic) body beneath the bay.

AAPG Search and Discovery Article #91038©1987 AAPG Annual Convention, Los Angeles, California, June 7-10, 1987.