Preliminary Geologic Map of the Big Costilla Peak area, Taos County, New Mexico, and Costilla County, Colorado By Christopher J. Fridrich, Ralph R. Shroba, and Adam M. Hudson GIS database By Theodore R. Brandt 2012 U.S. Geological Survey Open-File Report 2012-1041 ABSTRACT This map covers the Big Costilla Peak, New Mex.-Colo. quadrangle and adjacent parts of three other 7.5 minute quadrangles: Amalia, New Mex.-Colo., Latir Peak, New Mex., and Comanche Point, New Mex. The study area is in the southwesternmost part of that segment of the Sangre de Cristo Mountains known as the Culebra Range; the Taos Range segment lies to the southwest of Costilla Creek and its tributary, Comanche Creek. The map area extends over all but the northernmost part of the Big Costilla horst, a late Cenozoic uplift of Proterozoic (1.7-Ga and less than 1.4-Ga) rocks that is largely surrounded by down-faulted middle to late Cenozoic (about 40 Ma to about 1 Ma) rocks exposed at significantly lower elevations. This horst is bounded on the northwest side by the San Pedro horst and Culebra graben, on the northeast and east sides by the Devils Park graben, and on the southwest side by the (about 30 Ma to about 25 Ma) Latir volcanic field. The area of this volcanic field, at the north end of the Taos Range, has undergone significantly greater extension than the area to the north of Costilla Creek. The horsts and grabens discussed above are all peripheral structures on the eastern flank of the San Luis basin, which is the axial part of the (about 26 Ma to present) Rio Grande rift at the latitude of the map. The Raton Basin lies to the east of the Culebra segment of the Sangre de Cristo Mountains. This foreland basin formed during, and is related to, the original uplift of the Sangre de Cristo Mountains which was driven by tectonic contraction of the Laramide (about 70 Ma to about 40 Ma) orogeny. Renewed uplift and structural modification of these mountains has occurred during formation of the Rio Grande rift. Surficial deposits in the study area include alluvial, mass-movement, and glacial deposits of middle Pleistocene to Holocene age. DISCLAIMERS This database, identified as OF 2012-1041, has been approved for release and publication by the U.S. Geological Survey (USGS). Although this database has been subjected to rigorous review and is substantially complete, the USGS reserves the right to revise the data pursuant to further analysis and review. Furthermore, it is released on condition that neither the USGS nor the U.S. Government may be held liable for any damages resulting from its authorized or unauthorized use. Although these data have been processed successfully on a computer system at the U.S. Geological Survey (USGS), no warranty expressed or implied is made regarding the display or utility of the data on any other system, or for general or scientific purposes, nor shall the act of distribution constitute any such warranty. The USGS shall not be held liable for improper or incorrect use of the data described and/or contained herein. Any use of trade, product or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government. Although this information product, for the most part, is in the public domain, it also contains copyrighted material as noted in the text. Permission to reproduce copyrighted items for other than personal use must be secured from the copyright owner. CONTACT The database contact is: Theodore R. Brandt 303-236-1901 tbrandt@usgs.gov U.S. Geological Survey Box 25046, Mail Stop 980 Denver, CO 80225 CONTENTS The data were compiled from field mapping. E. M. Taylor and K. S. Kellogg, both of the U.S. Geological Survey, reviewed the geologic map. This geospatial database consists of ArcInfo export files (.e00) and ArcView shapefiles contained in a zip archive. Both compressed archive files contain both types of geospatial database files. See the list below. Please refer to the file OF2011-1041.met for detailed metadata documentation for this geospatial database. List of files: 00Readme.txt OF2012-1041_map.pdf OF2012-1041.met costbasr.tif (800 dpi tif mosaic base map of USGS topo) costbasr.tfw costbasr2(600).tif (600 dpi tif with embedded georegistration) OF2012-1041.zip: e00 directory: bigcgeo.e00 bigcpts.e00 bigcpta.e00 bigchlsd.e00 geol_sfo.lin.e00 geoscamp2.mrk.e00 import.aml wpgcmykg.shd.e00 shapefiles directory: bigcgeo.shp (.dbf/.prj/.sbn/.sbx/.shp/.shx/.xml) polygon bigcgeol.shp (.dbf/.prj/.sbn/.sbx/.shp/.shx/.xml) line bigcpta.shp (.dbf/.prj/.sbn/.sbx/.shp/.shx/.xml) point bigcpts.shp (.dbf/.prj/.sbn/.sbx/.shp/.shx/.xml) point OF2011-1041.gdb directory (contains GIS data as geodatabase feature classes) bigcgeo bigcgeol bigcpta bigcpts HOW TO OBTAIN THE DIGITAL FILES The database can be downloaded via the Web from http://pubs.usgs.gov/of/2012/1041/. An ArcGIS geodatabase, ArcInfo export files, and ArcView shapefiles may be extracted from a zip- compressed file (OF2012-1041.zip). In addition, an Adobe Portable Document Format (PDF) file(OF2012-1041_map.pdf) can be downloaded, from which paper copies may be printed. The main product is a Portable Document Format (.pdf) map, which requires Adobe Acrobat for viewing. Acrobat software runs on a variety of systems, and is available for download free of charge from Adobe at http://www.adobe.com.