Date of Award
8-17-2010
Document Type
Thesis
Abstract
The Miocene Bear Lake Formation (BLF) is a prospective hydrocarbon reservoir exposed on the southwestern Alaska Peninsula, extending into the subsurface to the northwest (reaching 2,360 m maximum thickness). This study comprehensively characterizes composition of BLF sandstones, and develops important implications for varying reservoir quality. Unique integration of standard petrographic methods, electron microprobe analysis (EMPA), and ⁴⁰Ar/³⁹Ar dating of detrital hornblende strengthens interpretations by providing multiple lines of evidence and a more complete picture of composition, source units and terrane, and diagenetic history than possible with petrography alone. EMPA provides superior classification of volcanic rock fragments and identification of diagenetic minerals. Results indicate a pressure-controlled diagenetic system, and a provenance more complicated than recycling of older strata, as currently interpreted. Simultaneous derivation from the Meshik Volcanics and recycling of Tolstoi, Chignik, and Naknek formations suggests erosion of a structurally-deformed source terrain (e.g. reverse-faulted anticlines). Abundance patterns of pore-filling zeolites, calcite, albite, and kaolinite likely represent variations in Pco₂ caused by variations in burial depth. Optimal reservoir quality is likely present in the subsurface upper BLF along the northwestern coast (and deeper in the basin), where sandstone composition is presumably more quartz-rich, less volcaniclastic, and has experienced higher Pco₂ fluid migration.
Recommended Citation
Hartbauer, Cheryl Lynne, "Provenance and diagenesis of the Miocene Bear Lake Formation, Bristol Bay basin, Alaska" (2010). Geosciences . 39.
https://ualaska.researchcommons.org/uaf_grad_geosci/39
Handle
http://hdl.handle.net/11122/5604