Source Rock Characterization and Petroleum Systems of Eocene Tyee Basin, Southern Oregon Coast Range, Usa
The hydrocarbon source rock potential of the Eocene Tyee basin in the southern Oregon Coast Range was evaluated using Rock-Eval pyrolysis. Most Eocene units in southern Oregon Coast Range are thermally immature and contain lean, gas prone Type III kerogen. However, some beds (coals) are sufficiently organic rich to be sources of biogenic and thermogenic methane discovered in numerous seeps. The overall hydrocarbon potential of the basin is moderately low, several requirements for commercial accumulations of hydrocarbons probably exist together locally within and adjacent to the basin. Three petroleum systems are identified in the basin. The first petroleum system appears near the southern border with the Mesozoic Klamath Mountains and is related to a proposed subduction zone maturation mechanism and migration of hydrocarbons along thrust faults. The second petroleum system is centered in the northern part of the basin and may be associated with unconventional plays associated with basin-center gas in overpressured zones in turbidite sandstones. The third petroleum system lies near the eastern border of the basin where maturation is related to local heating by sills and migration of hydrothermal fluids associated with mid-Tertiary volcanism in the Western Cascade arc.
AAPG Search and Discovery Article #90090©2009 AAPG Annual Convention and Exhibition, Denver, Colorado, June 7-10, 2009