Fluid flow and deformation history of the Denver basin, CO region: fluid inclusions, U-Pb geochronology and isotope geochemistry of calcite-filled fracture cements in the Niobrara Formation

The Colorado Front Range and adjacent Denver basin host a complex fracture network mainly formed during the Laramide orogeny initiating in the Late Cretaceous to middle Cenozoic by orogenesis, basin formation, and burial. The fracture network (e.g., joints, faults, open stylolites) acted as conduits for fluid flow. However, little to no constraints on the origin, temperature, composition, and timing of these fluid flow events exist. We address this through analysis of fracture-filling cements in the Niobrara Formation with the integration of petrographic and geochemical analyses including: LA-ICP-MS U-Pb geochronology, fluid inclusion microthermometry, stable isotope, and strontium isotope analysis. Samples were obtained from the Albert Kurtz well in the Wattenberg field, CO. Results obtained from several fracture fill types (e.g., crack-seal-slip, crack-seal and crack fill cements, tectonic stylolite-associated, joints) are consistent with multiple fluid flow events. Carbon and oxygen isotopic data indicate rock-water interaction with connate pore fluids. Strontium isotopic data corroborates this but suggests input of secondary fluids from a radiogenic source. Earliest fluid flow phases between 81-70 Ma are associated with polygonal faulting and expulsion of connate fluids, including petroleum. Possibly coeval and later episodic hydrothermal fluid flow likely occurred between ~81-65 Ma and was attributed to tectonic valving of deeper radiogenic-Sr-rich-aquifers during wrench fault activity and Rocky Mountain uplift. Upward vertical migration of hydrothermal fluids may be the most suitable explanation of the Wattenberg field thermal anomaly. These results provide a robust history of deformation and associated fluid flow events that may be applied to future tectonic studies and georesource exploration.

Grantor dc:publisher

University of Kansas

Year dc:date.issued

2024

Author dc:creator

• Center, Marc

Advisor dc:contributor.advisor

• Möller, Andreas

• Geology
• calcite veins
• Denver basin
• fluid flow
• Niobrara
• Wattenberg field

Language dc:language.iso

en

Dc Identifier Other

http://dissertations.umi.com/ku:19668

OAI identifier oai:identifier

oai:kuscholarworks.ku.edu:1808/38215