Pyrite-illite veins in basin-margin facies: evidence for detrital mineral control on pore-fluid evolution

Conference · Thu May 01 04:00:00 EDT 1986 · Am. Assoc. Pet. Geol., Bull.; (United States)

OSTI ID:5434524

Bloch, J D; Bhattacharyya, D P

Diagenesis of the Upper Cambrian Lamotte Sandstone includes the formation of euhedral, predominantly cubic pyrite, and 1M and 2M illite as veins in association with extensive quartz dissolution. The illite in these veins is well crystallized and distinct from pore-filling illite found in the same deposit. The veins occur only in shallow marine-deposited quartzarenites that overlie or are adjacent to basin-margin alluvial fan deposits composed primarily of lithic arenite. Detrital K-feldspar (in volcanic rock fragments) and iron-bearing minerals, particularly biotite, are abundant in the lithic arenites. No apparent source for the sulfur can be identified within the Lamotte Sandstone. Therefore, the authors propose that sulfur-bearing compactional or thermobaric fluids from adjacent basinal facies provided the necessary sulfur for pyrite formation. The migration of these fluids through the lithic arenite, from which iron, potassium, aluminum, and silica were derived, resulted in pyrite and illite deposition in the adjacent quartzarenites. The increased alkalinity and elevated temperature of these fluids resulted in the extensive quartz dissolution. The absence of these pyrite-illite veins in similar quartzarenites basinward of the fan deposits suggests a detrital mineral control on the evolution of these fluids as they migrated through the Lamotte Sandstone. Further, the formation of illite as opposed to kaolinite indicates that these fluids were finally alkaline.

• Research Organization: Washington Univ., St. Louis, MO
• OSTI ID: 5434524
• Report Number(s): CONF-860624-
• Conference Information: Journal Name: Am. Assoc. Pet. Geol., Bull.; (United States) Journal Volume: 70:5
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
020200* -- Petroleum-- Reserves
Geology
& Exploration
CAMBRIAN PERIOD
CHALCOGENIDES
CLAYS
DIAGENESIS
GEOLOGIC AGES
IRON COMPOUNDS
IRON SULFIDES
KAOLIN
MINERALOGY
MINERALS
ORIGIN
PALEOZOIC ERA
POROSITY
PYRITE
ROCKS
SANDSTONES
SEDIMENTARY ROCKS
SULFIDE MINERALS
SULFIDES
SULFUR COMPOUNDS
TRANSITION ELEMENT COMPOUNDS