CONSTRUCTING A SUBSIDENCE MODEL FOR THE EASTERN PORTION OF THE TAOS TROUGH THROUGH CORRELATION OF BACKSTRIPPED GEOHISTORY CURVES

The Taos trough is one of numerous depocenters that record late Paleozoic intraplate deformation known as the ancestral Rocky Mountains. An intra-basinal high ‘El-Oro-Rincon’ separates the basin into eastern and western half which was active during the Pennsylvanian. The western part of the Taos trough is thought to be a wrench basin. However, the aspect ratio of the eastern portion (i.e. the Rainsville trough) is larger than most strike-slip basins and no associated strike-slip faulting is known in this part of the basin which mandates a different style of subsidence. We plan to test an apt basin model for this area of the Taos trough region by backstripping a series of petrophysical well logs and correlating them to build a subsidence model.

A combined neutron-density porosity log with PEF curve and gamma ray curve were utilized to derive lithology from two wells located in the depocenter of the Rainsville trough. Obtained lithology was calibrated to a corresponding stratigraphic column from the literature and well completion reports to correlate among wells. Applying biostratigraphic controls from literature, constructed stratigraphic columns were subjected to backstripping to assess rate and magnitude of subsidence. Subsidence curves from these wells mimic each other and resemble flexural basin model for the Rainsville trough. Backstripped curves show subsidence was minimal until the Early Pennsylvanian; however, both the rate and magnitude of subsidence greatly increased during the Early Pennsylvanian. During the Late Pennsylvanian slope of the subsidence curve became shallower indicating relatively a tectonic quiescence period. Slope of the subsidence curve again steepened during the early Permian.

Stratigraphic thickness thins in wells located further east from the El-Oro-Rincon uplift and demonstrate similar subsidence curves, but with smaller magnitude all consistent with flexure basin loaded from the west implying structural thickening of the crust during the uplift of the El-Oro-Rincon uplift.