thumbnail

Neogene basins of the northern Rio Grande rift: Partitioning and asymmetry inherited from Laramide and older uplifts

Tectonophysics

By:
DOI: 10.1016/S0040-1951(99)00013-X

Links

Abstract

Three asymmetric Neogene basins in the northern Rio Grande rift of New Mexico and Colorado - the San Luis basin, the upper Arkansas River graben, and the Blue River graben - are tilted toward large flanking normal faults and lie astride the similarly asymmetric Late Cretaceous-early Tertiary (Laramide) San Juan-San Luis, Sawatch, and Front Range-Gore Range uplifts, respectively. The steep, thrust-faulted side of each uplift is on the same side as the down-rotated side of each of the Neogene basins. In addition, the direction of stratal tilt changes northward across the Villa Grove accommodation zone from east in the San Luis basin to west in the upper Arkansas River graben. This accommodation zone coincides approximately with the northward change from the east-directed San Juan-San Luis uplift to the west-directed Sawatch uplift. These observations, supported by seismic-reflection studies across the San Luis basin and studies of several other superimposed pairs of rift basins and Laramide uplifts, suggest that the basin-bounding normal faults are listric and merge at depth with the older thrusts, which are also listric and root into the crust at about 15-16 km. The Blue River graben is complicated by lack of basin fill and a thrust history along the west side of the Gore Range that is at least as old as late Paleozoic. Nonetheless, the Neogene valley is demonstrably tilted west and lies astride an overall west-directed thrust system, similar to other thrust-and-basin relationships in the northern Rio Grande rift.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Neogene basins of the northern Rio Grande rift: Partitioning and asymmetry inherited from Laramide and older uplifts
Series title:
Tectonophysics
DOI:
10.1016/S0040-1951(99)00013-X
Volume
305
Issue:
1-3
Year Published:
1999
Language:
English
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Tectonophysics
First page:
141
Last page:
152
Number of Pages:
12