Possible Quaternary Faulting on the Picuris-Pecos Fault on the Eastern Margin of the Española Basin, New Mexico
Description:
The north-south-trending continental Rio Grande Rift (RGR) extends for ~1,000 km from Chihuahua, MX to northern Colorado, USA. Within the central RGR, the Española Basin is a ~60 km wide, west-tilted half graben with low seismicity rates, low slip rates on Quaternary-active faults (0.01–0.1 mm/yr), and a low geodetic extension rate. The western-basin-bounding Pajarito fault system has generated surface rupture during large (>M6) earthquakes during the Holocene, and there is strong evidence for late Pleistocene and possibly Holocene surface ruptures on other faults within the basin. On the eastern side of the basin, the Picuris-Pecos fault (PPF) forms the eastern boundary of the RGR. While most of the extensional strain is partitioned to active faults on the western side of the basin, we show that new neotectonic mapping on 1 m lidar-derived topography indicates that at least one strand of the PPF has displaced moraines that are undated, but presumably date to the last glacial maximum based on regional correlations. Field reconnaissance of the lineaments confirmed the presence of <1 m-high, down-to-the-west and down-to-the-east scarps that offset several moraine crests and younger surfaces between the moraines. On another strand, abrupt, NNE-trending topographic lineaments persist for at least ~7 km and are part of a discontinuous, ~65 km-long lineament set that traverses the western side of the Sangre De Cristo Mountains. The lineaments cross disparate geological units and topography, suggesting they have a tectonic origin. Field reconnaissance confirmed the presence of the lineaments, which form topographic benches that cross steep, bedrock-mantled slopes obliquely in places. 10Be exposure dating of boulders on the displaced moraines and additional mapping along other lineaments on the trace of the PPF will improve our understanding of the most recent surface deformation and location of the PPF, in addition to better characterization of site-specific and regional seismic sources.
Session: From Faults to Fjords: Earthquake Evidence in Terrestrial and Subaqueous Environments [Poster Session]
Type: Poster
Date: 5/1/2024
Presentation Time: 08:00 AM (local time)
Presenting Author: Michael
Student Presenter: No
Invited Presentation:
Authors
Michael Cline Presenting Author Corresponding Author mcline@usbr.gov U.S. Bureau of Reclamation |
Jessica Thompson Jobe jjobe@usgs.gov U.S. Geological Survey |
Nadine Reitman nreitman@usgs.gov U.S. Geological Survey |
Richard Briggs rbriggs@usgs.gov U.S. Geological Survey |
Nicholas Ellett nellett@usbr.gov U.S. Bureau of Reclamation |
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Possible Quaternary Faulting on the Picuris-Pecos Fault on the Eastern Margin of the Española Basin, New Mexico
Session
From Faults to Fjords: Earthquake Evidence in Terrestrial and Subaqueous Environments