--> ABSTRACT: Niobrara Source Rock Maturity along the Extrapolated Trend of the Colorado Mineral Belt in the Denver Basin, by Thul, David J.; Sonnenberg, Stephen A.; #90142 (2012)

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Niobrara Source Rock Maturity along the Extrapolated Trend of the Colorado Mineral Belt in the Denver Basin

Thul, David J.*1; Sonnenberg, Stephen A.1
(1) Department of Geology and Geological Engineering, Colorado School of Mines, Golden, CO.

The extent of effective source rock in the Niobrara has long been tied to its present day structural position. While it is a reasonable assumption that maturity increases with depth, the Denver Basin’s complex structural and thermal history has caused significant deviation from this model.

The most obvious deviation from depth-controlled maturity in the basin is Wattenberg Field and the associated Wattenberg Thermal Anomaly (WTA). The WTA is seen by some as an extension of the Colorado Mineral Belt (COMB) into the adjacent sedimentary basin.

We extrapolate this trend further to the northeast using the northwest and southeast borders of the Wattenberg Field gas production as well as trends of mineralization seen in the mining districts to the southwest. In doing so, we infer an axis for the COMB trend that extends beyond the evidence of recent mineralization and well into the eastern flank of the basin.

Using programmed pyrolysis data from cores and cuttings samples within and adjacent to the inferred COMB trend we show that, along structural contours, maturity increases with proximity to the COMB axis. Additionally we show that Niobrara source rock maturity extends to the northeast in a much more focused manner than previously thought.

 

AAPG Search and Discovery Article #90142 © 2012 AAPG Annual Convention and Exhibition, April 22-25, 2012, Long Beach, California