Stable isotope geochemistry of carbonate fracture fills in the Monterey Formation, California

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doi: 10.1306/D42678C5-2B26-11D7-8648000102C1865D
Authors:Winter, Bryce L.; Knauth, L. Paul
Author Affiliations:Primary:
Ariz. State Univ., Dep. Geol., Tempe, AZ, United States
Volume Title:Journal of Sedimentary Petrology
Source:Journal of Sedimentary Petrology, 62(2), p.208-219. Publisher: Society of Economic Paleontologists and Mineralogists, Tulsa, OK, United States. ISSN: 0022-4472
Publication Date:1992
Note:In English. 43 refs.; illus. incl. 2 tables, sketch map
Summary:Carbonate minerals filling fractures in the Monterey Formation at four locations along the Santa Barbara Channel coast display a δ18O(SMOW) range from 20.7 to 35.7 per thousand and δ13C range from - 18.6 to + 16.6 per thousand . Many fracture fills display a covariation of δ18O and δ13C, and successive generations of carbonate have lower δ18O values. These isotope systematics can be interpreted in terms of δ18O values that were controlled by crystallization temperatures and the δ18O of connate pore water, and δ13C values that were controlled by depth-sequential organic matter degradation reactions. Each successive generation of carbonate precipitated at progressively higher burial temperatures from isotopically evolving connate pore water. These carbonate-filled fractures developed during burial and not during uplift. Using crystallization temperature estimates from fluid inclusion data, the change in δ18O of conate pore water with increasing temperature in the burial environment is modeled. From this model, the fracture fill δ18O values indicate precipitation over the following temperature intervals: 25-70°C (Carpinteria Beach), 7-15°C (Goleta Slough Beach), 45-100°C (Refugio Beach), and 53-103°C (Jalama Beach).
Subjects:C-13/C-12; Carbon; Carbonaceous composition; Carbonate rocks; Cenozoic; Connate waters; Crystallization; Fluid inclusions; Fractures; Geochemistry; Inclusions; Isotopes; Miocene; Monterey Formation; Neogene; O-18/O-16; Oxygen; Reservoir rocks; Sedimentary rocks; Stable isotopes; Tertiary; California; Santa Barbara Channel; United States
Abstract Numbers:93M/715
Record ID:1992024272
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute.
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