--> Abstract: Oil in Carlin-Type, Sediment-Hosted Gold Deposits: Significance for Petroleum Exploration, by J. B. Hulen, J. W. Cox, D. L. Nielson, and J. C. Lamborn; #90987 (1993).

Datapages, Inc.Print this page

HULEN, JEFFREY B., Univ. of Utah Research Institute, Salt Lake City, UT; JOHN W. COX, USMX, Inc., Reno, NV; DENNIS L. NIELSON, Univ. of Utah Research Institute, Salt Lake City, UT; and JOHN C. LAMBORN, USMX, Inc., Reno, NV

ABSTRACT: Oil in Carlin-Type, Sediment-Hosted Gold Deposits: Significance for Petroleum Exploration

At least three of the Carlin-type, low-grade, sediment-hosted hydrothermal gold deposits of the Alligator Ridge mining district, Nevada, contain abundant live oil, a phenomenon with potentially important implications for global petroleum exploration. The Yankee, Casino, and Winrock deposits share numerous attributes with others of the Carlin-type, including occurrence in Paleozoic siliciclastic and carbonate strata, hydrocarbon enrichment or remobilization, and porosity enhancement by massive carbonate dissolution. Quartz and/or calcite veinlets in the three deposits are rich in primary, live-oil-bearing fluid inclusions, entrapped at temperatures ranging from about 40 degrees C (Casino) to about 165 degrees C (Winrock). The inclusions at Yankee (about 90 degrees), moreover, occur in uggy, open calcite veinlets which yielded impressive quantities of freely-flowing oil during mining operations. (The Yankee "oil reservoir," prior to oxidation, may have contained more than 700,000 BO). From these relationships, we suggest thefollowing: (1) Petroleum was transported and entrapped by the same hydrothermal systems responsible for gold mineralization; (2) Porosity for oil entrapment and mineralization was created by hydrothermal carbonate dissolution, perhaps induced by circulating thermal fluids charged with organic acids; (3) In the presence of petroleum, mineralization occurred at temperatures much lower than considered typical (180-290 degrees C) for the Carlin-type deposits in general -- a happenstance favoring preservation of the entrapped oil; (4) Exploration techniq es routinely applied in the search for such gold deposits might be effectively utilized to discover concealed "Carlin-type" oil fields.

AAPG Search and Discovery Article #90987©1993 AAPG Annual Convention, New Orleans, Louisiana, April 25-28, 1993.