Proterozoic oil in fluid inclusions in the midcontinent rift: Implications for the origin of oil at White Pine, Michigan

Conference · Wed Jan 01 04:00:00 EST 1992 · Geological Society of America, Abstracts with Programs; (United States)

OSTI ID:5806832

Burruss, R C ^[1]; Mauk, J L ^[2]

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1. Geological Survey, Denver, CO (United States)
2. Univ. of Michigan, Ann Arbor, MI (United States). Dept. of Geological Sciences

Oil-filled fluid inclusions, some of which are primary, were trapped in calcite veins in the Nonesuch Formation during second-stage copper mineralization related to a 1.05-Ga compressional event in the Midcontinent rift at White Pine. Yellow to orange fluorescent inclusions in 14 samples of calcite were analyzed by a crushing-cell, capillary gas chromatographic method capable of resolving C[sub 1] to > C[sub 30] hydrocarbons. The inclusions contain an n-alkane-rich liquid petroleum that includes a homologous series of monomethylalkanes and is generally similar to previously reported oils from seeps in the White Pine mine. The C[sub 1] to C[sub 17] fraction of the oils shows extensive but variable loss of normal, branched, cyclic, and aromatic hydrocarbons. Patterns of depletion are consistent with published laboratory simulations of water-washing and are different from patterns due to devolatilization or biodegradation. Water/oil ratios necessary to produce the alteration range from 10[sup 3] to greater than 10[sup 6], suggesting that only very small amounts of liquid hydrocarbons migrated with 100 C hydrothermal fluids during second-stage copper mineralization at White Pine. C[sub 4]-C[sub 7] compound ratios in the least altered samples suggest generation of crude oils from kerogen with aliphatic characteristics similar to that found in the Nonesuch Fm. outside the mine locality. The estimates of thermal maturity from C[sub 4]-C[sub 7] compound ratios imply oil generation at an equivalent vitrinite reflectance > 1.0, which is higher than that estimated for the hydrothermally altered sediments at White Pine. The authors conclude that the oil in inclusions was generated from the Nonesuch Formation outside the mine locality in more thermally mature parts of the Midcontinent rift, was extensively water-washed during migration and interaction with Cu-bearing hydrothermal fluids, and was not biodegraded.

• OSTI ID: 5806832
• Report Number(s): CONF-921058--
• Conference Information: Journal Name: Geological Society of America, Abstracts with Programs; (United States) Journal Volume: 24:7
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
020200 -- Petroleum-- Reserves
Geology
& Exploration
58 GEOSCIENCES
580000* -- Geosciences
BITUMINOUS MATERIALS
CARBONACEOUS MATERIALS
CHEMISTRY
COPPER ORES
DEVELOPED COUNTRIES
ENERGY SOURCES
ENVIRONMENTAL TRANSPORT
FOSSIL FUELS
FUELS
GEOCHEMISTRY
GEOLOGIC AGES
GEOLOGIC FORMATIONS
GEOLOGIC STRUCTURES
INCLUSIONS
KEROGEN
MASS TRANSFER
MATERIALS
MATTER
MATURATION
MICHIGAN
MINERALIZATION
MOLECULAR WEIGHT
NORTH AMERICA
ORES
ORGANIC MATTER
ORIGIN
PETROLEUM
PRECAMBRIAN ERA
RIFT ZONES
SEEPS
STRUCTURAL CHEMICAL ANALYSIS
USA