Field Trip, GeoPrisms RIE-TEI 2017 Field Trip Leaders: Karl Karlstrom, Laura Crossey, Tobias Fischer Materials on Kasha Katuwe from: Profs. Gray Smith & Aurora Pun The Geological Society of America Special Paper 494 2013 Introduction Mark R. Hudson U.S. Geological Survey, MS 980, Federal Center, Denver, Colorado 80225, USA V.J.S. Grauch U.S. Geological Survey, MS 964, Federal Center, Denver, Colorado 80225, USA Basins of the Rio Grande rift have long been studied both OVERVIEW OF THE RIO GRANDE RIFT for their record of rift development and for their potential as host of natural resources. Early workers described the basin geomor- The Rio Grande rift extends from Colorado, USA, on the phology and the character of infi lling sediments (e.g., Siebenthal, north to the state of Chihuahua, Mexico, on the south, dividing 1910; Bryan, 1938; Speigel and Baldwin, 1963), and subsequent the Colorado Plateau on the west from the interior of the North research compilations provided general stratigraphic and tectonic American craton on the east (Fig. 1). It is named for the Rio overviews of rift basins and described their geophysical charac- Grande, the major river that fl ows through most of its extent. teristics within the crust (Hawley, 1978; Riecker, 1979; Baldridge Beginning with the paper by Chapin (1971), it has been widely et al., 1984; Keller, 1986). Subsurface knowledge gained from recognized as a major late Cenozoic continental rift zone that is hydrocarbon exploration activities coupled with detailed surface distinct from, but related to, the wider zone of extension in the studies of basins and their fl anking uplifts were presented in Geo- Basin and Range region of the southwestern USA (Keller and logical Society of America (GSA) Special Paper 291, edited by Cather, 1994b; Baldridge et al., 1995). Keller and Cather (1994a). These studies addressed the structure, Within the upper crust, the rift is characterized by a series of stratigraphy, and tectonic setting of individual basins spanning interconnected structural basins fi lled with thick accumulations almost the entire length of the rift. Structural models of rifting of clastic sediments and local interbedded basalt fl ows. Several presented in GSA Special Paper 291 have guided exploration for late Cenozoic volcanic fi elds are associated with the rift (Fig. 1), and management of natural resources and have been held as stan- but the volume of magmatism is generally low in comparison to dards for comparison to other continental rifts (e.g., Faulds and other continental rifts (Keller and Baldridge, 1999). An obvious Varga, 1998). Since publication of GSA Special Paper 291, a new east-northeast alignment of late Cenozoic volcanic fi elds, known generation of researchers has joined efforts to further investigate as the Jemez lineament, crosses the rift between the Española the basins of the Rio Grande rift, driven in large part by the need and San Luis Basins and coincides with the orientations of rift- to better understand the important groundwater resources held age structures such as the Embudo fault zone (Fig. 1). Workers by rift basins (e.g., Bartolino and Cole, 2002). The research has have long speculated that the lineament is a long-lived basement led to abundant new geologic, geophysical, and hydrogeological weakness that infl uenced rift development and was a conduit data that were highlighted in a special topical session at the GSA for magma (e.g., Lipman, 1980; Aldrich and Laughlin, 1984), a Annual Meeting in 2007. This volume is an outcome of that ses- speculation that is supported by recent deep seismic experiments sion, and includes papers that demonstrate the new perspectives (Magnani et al., 2004). on the rift and its basins that have developed from the new data, Topographically, the rift is associated with a series of elon- discoveries, and interpretations since 1994. We note, however, gated valleys fl anked by northerly or northwesterly trending that rift research marches on and new data and insights continue mountain ranges (Fig. 2). Individual valleys of the Rio Grande to emerge, as highlighted at the GSA Rocky Mountain Section rift are easy to recognize in Colorado and northern New Mexico, meeting in 2012. but diffi cult to distinguish from the physiography of the broader Hudson, M.R., and Grauch, V.J.S., 2013, Introduction, in Hudson, M.R., and Grauch, V.J.S., eds., New Perspectives on Rio Grande Rift Basins: From Tectonics to Groundwater: Geological Society of America Special Paper 494, p. v–xii, doi:10.1130/2013.2494(00). For permission to copy, contact [email protected]. © 2013 The Geological Society of America. All rights reserved. v vi Hudson and Grauch 110°W 104°W 40°N 108°W 106°W Denver Upper Arkansas River Basin TMVF San Luis Basin 38°N SJVF AlamosaAlamosa CG UT CO AZ NM OK AE Española TX Basin EFZ 36°N Figure 1. Main features of the Rio Grande rift, showing basins and precursory and JVF SantaSanta FeFe associated volcanic fi elds. Basins and TCFZ volcanic fi elds discussed in this volume Santo Domingo Basin are labeled. Volcanic fi elds are denoted AlbuquerqueAlbuquerque by large capital letters: JVF—Jemez JEMEZ LINEAMENT volcanic fi eld; MDVF— Mogollon-Datil volcanic fi eld; SJVF—San Juan volcanic Albuquerque fi eld; TMVF—Thirtynine Mile volca- Basin nic fi eld; TPVF—Trans-Pecos volcanic 34°N Socorro fi eld. Additional geographic and geo- logic features are denoted by small capi- tal letters: AE—Abiquiu embayment; MDVF CG—Culebra graben; EFZ—Embudo fault zone; TCFZ—Tijeras-Cañoncito fault zone; TMFZ—Tascotal Mesa fault zone. AZ—Arizona; CO—Colorado; NM—New Mexico; OK—Oklahoma; LasLas CrucesCruces TX—Texas; UT—Utah. Mimbres NM 32°N Basin EEll PPasoaso TX BASIN AND RANGE Hueco AZ Basin Mexico Salt Basin TPVF 30°N Late Tertiary-Quaternary volcanic fields TMFZTMFZ Presidio Middle Tertiary-Quaternary rift sediments Graben Middle Tertiary volcanic fields 0100 Sunken Rio Grande Block kilometers Introduction vii 110°W 104°W 40°N 108°W 106°W Upper Arkansas River Basin 38°N San Luis Basin Española Basin 36°N Santo Domingo Basin JEMEZ LINEAMENT Figure 2. Color shaded-relief topograph- ic map for the region of the Rio Grande Albuquerque rift. Outlines of basins and the Jemez lin- Basin eament from Figure 1. Digital elevation 34°N model is from the National Aeronautics and Space Administration (NASA) shut- tle radar topography mission. Mimbres 32°N Basin Hueco Basin Salt Basin 30°N Outline of Rio Grande rift Presidio Rio Grande Graben City 0100 Sunken Block kilometers viii Hudson and Grauch Basin and Range in southern New Mexico, west Texas, and lows Keller et al. (1990), where they observed a general transi- northern Mexico. Moreover, rift-related sedimentary and volca- tion from higher heat fl ow, somewhat thinner crust, and greater nic deposits are found outside of the valleys, and basin boundar- Quaternary fault activity on the east compared to the west. The ies do not always conform to valley margins. Thus, the names gravity map (Fig. 3) suggests that the zone of prominent north- and extents of basins and subbasins of the rift are inconsistently westerly trends crosses the rift, extending from the vicinity of depicted in the literature. Some workers use only physiography to El Paso, Texas, as far northwest as southeastern Arizona. Within defi ne the basins; other workers use major structural boundaries these areas, tectonic features ranging in age from Paleozoic to combined with physiography; yet others use the lateral extents of Cenozoic all have dominantly northwesterly trends (e.g., Seager, rift-related deposits, either inclusive or exclusive of the volcanic 2004), suggesting possible genetic relationships. fi elds. Readers should be aware that we have not attempted to Although not the focus of this volume, much recent research reconcile these differences among the papers in this volume. The has centered on exploring the lithosphere and mantle below the rift basins of Figure 1 are outlined using a combination of physi- Rio Grande rift, motivated in large part by two deep-looking ography, limits of Neogene sedimentary deposits, and structure, seismic experiments that cross the rift obliquely: the Continen- using the following previous rift defi nitions and geologic maps tal Dynamics–Rocky MOuntain project (CD-ROM) and Colo- as guides: Tweto et al. (1979), Keller et al. (1990), Keller and rado Plateau/Rio Grande Rift Seismic Transect (LA RISTRA) Cather (1994b), Dickerson and Muehlberger (1994), Baldridge et experiments. These experiments show shallow, seismically slow al. (1995), Richard et al. (2000), New Mexico Bureau of Geology mantle below the Rio Grande rift (Karlstrom et al., 2005; Gao and Mineral Resources (2003), and Garrity and Soller (2009). et al., 2004; Wilson et al., 2005), consistent with upper-mantle Gravity maps can be used to enhance the view of the struc- convection and high heat fl ow in the rift and neighboring Jemez tural setting of the rift. Gravity lows are produced by thick sec- lineament (Reiter, 2009). tions of sediments within the structural basins, and steep gra- Previous workers have noted an increase in extension across dients are associated with large vertical displacements at basin the rift from north to south, prompting them to theorize that the borders (Cordell, 1978). Although lows are produced by a wide rift is opening as a result of rotation of the Colorado Plateau (e.g., variety of other geologic features as well, the lows within the Cordell, 1982; Chapin and Cather, 1994). However, present-day outlined basins of the rift provide general clues to the locations of relative motions of the Colorado Plateau and Rio Grande rift their deepest parts. Isostatic residual gravity data (Fig. 3) refl ect observed from GPS stations are inconsistent with this type of density variations in the upper crust.