Timing, Mechanisms and Modes of Cenozoic Fracturing and Deformation in the Southern Raton Basin, Northern New Mexico

Scott M. Larson and Edmund R. Gustason
El Paso Exploration & Production, Denver, CO

The Raton Basin is a highly asymmetric Laramide basin that lies immediately east of the Sangre de Cristo Mountains of south-central Colorado and northern New Mexico. The Raton Basin is unique amongst Laramide basins as late Cenozoic erosion hasn’t removed the majority of its syn-, and post-orogenic strata. Synorogenic strata were subsequently intruded in the Oligocene by mafic dikes which trend approximately perpendicular to the basin axis. The onset of Rio Grande Rifting and associated intrusive and extrusive igneous activity in the early Miocene and their continuation through the Neogene provide a detailed record of the tectonic stress regimes in northern New Mexico for over 60 Ma.

New and previously published kinematic data collected from across the basin are used in an attempt to constrain the orientations of Laramide stress and strain in the southern Raton Basin and adjacent Sangre de Cristo Mountains. We will present new balanced structural cross sections constrained by recently published geologic mapping and proprietary seismic and well data and discuss the implications of 2D modeling on the styles and modes of Laramide deformation. New and published surface fracture data, natural and induced fracture data from proprietary CBM well logs and earthquake focal mechanism data are utilized to constrain the modern stress regime within the lithosphere. We will then discuss the implications of these and other stress data and introduce hypotheses for both the mechanism and timing of jointing in the southern Raton Basin.

AAPG Search and Discovery Article #90092©2009 AAPG Rocky Mountain Section, July 9-11, 2008, Denver, Colorado