Cenozoic Landscape Evolution of the Southern Rocky Mountains Completed
The Cenozoic Landscape Evolution of the Southern Rocky Mountains Project is a multi-year investigation funded by the National Cooperative Geologic Mapping Program. This project utilizes a combination of geologic mapping, geophysical surveys, basin modeling, and structural, neotectonic, geomorphic, volcanic, stratigraphic, and geochronologic studies to better understand the geologic landscape of the southern Rocky Mountains province.
The southern Rocky Mountains province extends through northern New Mexico, Colorado, and southern Wyoming. This area has a diverse and protracted geologic history dominated by contractional Laramide deformation, attendant basin sedimentation, and Andean-type arc volcanism during the early Cenozoic. In contrast, the Neogene and Quaternary have been dominated by broadly distributed crustal extension and intra-arc basin formation that are concurrent with Rio Grande rifting. The geologic framework of this part of the Rocky Mountains is well mapped and characterized in some places, but emphasis in these areas is commonly placed on narrow geologic time periods or specific tectonic and orogenic episodes. Remarkably, other regions of this mountain province still have not been adequately mapped and studied to accurately define even temporally limited geologic frameworks. Moreover, linkages between past geologic and climatic processes and events, and paleo to recent landscape change have not been fully and systematically explored across the province.
In this project we explore the Cenozoic geologic history of the southern Rocky Mountains region through an integrated study of:
Geophysics and Subsurface Investigation
Plio-Pleistocene Geomorphic Evolution
Fundamental Questions
Some fundamental questions that the project aims to address are:
- How have Neogene and younger crustal extensional strain and volcanism associated with Rio Grande rifting been transferred and distributed across the Southern Rocky Mountains?
- Have this strain and volcanism been influenced by earlier Laramide structures or subduction-related magmatism?
- How have the extensional strain, volcanism, and basin sedimentation controlled the development of landscapes defining the modern physiography of the province?
- How have climatically and tectonically driven events of the Neogene and Quaternary influenced establishment and integration of modern drainage patterns?
Significance
Many of the objectives of this project also address societal issues related to groundwater management, geothermal and traditional energy resources, and seismic hazards. The Southern Rocky Mountains encompass strategic mineral and fossil fuel reserves, agricultural resources, groundwater aquifers, and headwaters of four major intermontane river drainages that sustain and provide energy for a rapidly growing population that currently numbers more than 5 million just in Colorado alone. Linked by the through-flowing rivers (Rio Grande, Arkansas, Colorado, and Platte) along tectonic troughs of the Rio Grande rift or incised mountain valleys, the vitality of intermountain basin and Front Range communities and economies depends on a growing supply of water extracted from complex aquifers, mostly in rift-basin sediments. The groundwater is controlled by the subsurface geology, including basin aquifer thickness, buried faults and basement structure, and fault configurations at the mountain front recharge zones.
Energy resources, in the form of oil, gas, and geothermal, are found in basins or at their margins throughout the southern Rocky Mountain region. In particular, geologic controls on geothermal resources are poorly understood yet there is new impetus for the Rocky Mountain States to investigate and develop these resources.
Finally, the Rio Grande rift is still considered seismically active even though few historic earthquakes have been recorded. Evidence of large-magnitude Quaternary earthquakes with recurrence intervals of 10–140 ka suggests that these faults could be particularly dangerous. Long periods of seismic quiescence allow active fault scarps to be obscured by erosion and make them difficult to map.
Over three-quarters of the proposed study area is administered as public lands, including Rocky Mountain National Park, Great Sand Dunes National Park, Rio Grande del Norte National Park (est. 2013), Bandelier National Monument, National Forests, Bureau of Land Management lands, and US Fish and Wildlife Service wetlands areas. Each year millions of tourists and outdoor enthusiasts visit and depend on these public lands to recreate and enjoy their natural beauty and resources. Managing critical renewable and non-renewable resources, protecting wildlife and ecosystems, and providing viable recreational opportunities are reliant on understanding the underlying geologic controls on water quality and quantity, mineral deposits, fossil fuel reserves, and landscape and ecosystem stability.
Objectives
Cenozoic tectonics, magmatism, surface processes and landscape evolution are linked by geodynamic processes and are manifested geologically at a range of scales. The earth’s surface reflects the complex interplay of global-scale tectonic plate motions, heat flow, mantle anisotropy, crustal heterogeneity, and climate change. The impact of these forces on the earth’s diverse and spatially varying material properties results in a complex response whereby crustal geomorphic evolution can be dramatically influenced by both internal and external factors. The surface expression of tectonic faulting and folding, associated rock uplift, and construction of large volcanic edifices derived from the transient changes in lithospheric heat flow, drives a geomorphic response. This, in concert with climatic influence, can result in dramatic landscape change, including the establishment of new drainage patterns, basin sedimentation rates, and provenance history. Likewise, fault conduits influence emplacement of magma chambers in the shallow crust that, upon eruption, can alter drainage and sedimentation patterns and, in the case of large magmatic fields, influence climate. The primary geologic influences on ecosystem evolution, drainage history, water resources quantity and quality, mineral resource, oil and gas potential, and geohazards are universally linked through coupled surface processes, geomorphic evolution, and geodynamics.
Strategy and Approach
This project investigates the geologic framework and evolution of a broad swath of the Southern Rocky Mountains between northern New Mexico and southern Wyoming, focusing on linkages to Cenozoic landscape development. Initial project efforts concentrate on two key areas at opposite ends of the project footprint that have traditionally been viewed as having distinct, contrasting geologic styles and histories:
- Basins and flanking ranges of the northern Rio Grande rift (northern New Mexico and southern Colorado) dominated by Neogene extensional tectonics, volcanism, and sedimentation and the North-Middle Park region (northern Colorado) dominated by Laramide contractional deformation and sedimentation.
- The North-Middle Park region (northern Colorado) dominated by Laramide contractional deformation and sedimentation.
Early focus in these two regions builds on geologic mapping and investigations conducted on predecessor, National Cooperative Geologic Mapping Program-funded Rio Grande Basins and Colorado Headwaters Basin projects. Moreover, these initial project foci will result in detailed and comprehensive datasets to compare "end-member" tectonic influences and histories and allow opportunities to document under-recognized transitional and overprinted tectonic and magmatic signatures and attendant landscape changes. Project efforts will eventually expand to other uplifted mountain blocks and basins (or "parks") to similarly investigate and document their local geologic frameworks and their influences on landscape evolution.
Below are publications associated with this project.
Expression of terrain and surface geology in high-resolution helicopter-borne gravity gradient (AGG) data: examples from Great Sand Dunes National Park, Rio Grande Rift, Colorado
Late Miocene-Pleistocene evolution of a Rio Grande rift subbasin, Sunshine Valley-Costilla Plain, San Luis Basin, New Mexico and Colorado
Preliminary geologic map of the Bowen Mountain quadrangle, Grand and Jackson Counties, Colorado
Beyond Colorado's Front Range - A new look at Laramide basin subsidence, sedimentation, and deformation in north-central Colorado
The search for Braddock’s Caldera— Guidebook for Colorado Scientific Society Fall 2008 field trip, Never Summer Mountains, Colorado
- Overview
The Cenozoic Landscape Evolution of the Southern Rocky Mountains Project is a multi-year investigation funded by the National Cooperative Geologic Mapping Program. This project utilizes a combination of geologic mapping, geophysical surveys, basin modeling, and structural, neotectonic, geomorphic, volcanic, stratigraphic, and geochronologic studies to better understand the geologic landscape of the southern Rocky Mountains province.
The southern Rocky Mountains province extends through northern New Mexico, Colorado, and southern Wyoming. This area has a diverse and protracted geologic history dominated by contractional Laramide deformation, attendant basin sedimentation, and Andean-type arc volcanism during the early Cenozoic. In contrast, the Neogene and Quaternary have been dominated by broadly distributed crustal extension and intra-arc basin formation that are concurrent with Rio Grande rifting. The geologic framework of this part of the Rocky Mountains is well mapped and characterized in some places, but emphasis in these areas is commonly placed on narrow geologic time periods or specific tectonic and orogenic episodes. Remarkably, other regions of this mountain province still have not been adequately mapped and studied to accurately define even temporally limited geologic frameworks. Moreover, linkages between past geologic and climatic processes and events, and paleo to recent landscape change have not been fully and systematically explored across the province.
In this project we explore the Cenozoic geologic history of the southern Rocky Mountains region through an integrated study of:
Geophysics and Subsurface Investigation
Plio-Pleistocene Geomorphic Evolution
Fundamental Questions
Some fundamental questions that the project aims to address are:
- How have Neogene and younger crustal extensional strain and volcanism associated with Rio Grande rifting been transferred and distributed across the Southern Rocky Mountains?
- Have this strain and volcanism been influenced by earlier Laramide structures or subduction-related magmatism?
- How have the extensional strain, volcanism, and basin sedimentation controlled the development of landscapes defining the modern physiography of the province?
- How have climatically and tectonically driven events of the Neogene and Quaternary influenced establishment and integration of modern drainage patterns?
Significance
Many of the objectives of this project also address societal issues related to groundwater management, geothermal and traditional energy resources, and seismic hazards. The Southern Rocky Mountains encompass strategic mineral and fossil fuel reserves, agricultural resources, groundwater aquifers, and headwaters of four major intermontane river drainages that sustain and provide energy for a rapidly growing population that currently numbers more than 5 million just in Colorado alone. Linked by the through-flowing rivers (Rio Grande, Arkansas, Colorado, and Platte) along tectonic troughs of the Rio Grande rift or incised mountain valleys, the vitality of intermountain basin and Front Range communities and economies depends on a growing supply of water extracted from complex aquifers, mostly in rift-basin sediments. The groundwater is controlled by the subsurface geology, including basin aquifer thickness, buried faults and basement structure, and fault configurations at the mountain front recharge zones.
Energy resources, in the form of oil, gas, and geothermal, are found in basins or at their margins throughout the southern Rocky Mountain region. In particular, geologic controls on geothermal resources are poorly understood yet there is new impetus for the Rocky Mountain States to investigate and develop these resources.
Finally, the Rio Grande rift is still considered seismically active even though few historic earthquakes have been recorded. Evidence of large-magnitude Quaternary earthquakes with recurrence intervals of 10–140 ka suggests that these faults could be particularly dangerous. Long periods of seismic quiescence allow active fault scarps to be obscured by erosion and make them difficult to map.
Over three-quarters of the proposed study area is administered as public lands, including Rocky Mountain National Park, Great Sand Dunes National Park, Rio Grande del Norte National Park (est. 2013), Bandelier National Monument, National Forests, Bureau of Land Management lands, and US Fish and Wildlife Service wetlands areas. Each year millions of tourists and outdoor enthusiasts visit and depend on these public lands to recreate and enjoy their natural beauty and resources. Managing critical renewable and non-renewable resources, protecting wildlife and ecosystems, and providing viable recreational opportunities are reliant on understanding the underlying geologic controls on water quality and quantity, mineral deposits, fossil fuel reserves, and landscape and ecosystem stability.
Objectives
Cenozoic tectonics, magmatism, surface processes and landscape evolution are linked by geodynamic processes and are manifested geologically at a range of scales. The earth’s surface reflects the complex interplay of global-scale tectonic plate motions, heat flow, mantle anisotropy, crustal heterogeneity, and climate change. The impact of these forces on the earth’s diverse and spatially varying material properties results in a complex response whereby crustal geomorphic evolution can be dramatically influenced by both internal and external factors. The surface expression of tectonic faulting and folding, associated rock uplift, and construction of large volcanic edifices derived from the transient changes in lithospheric heat flow, drives a geomorphic response. This, in concert with climatic influence, can result in dramatic landscape change, including the establishment of new drainage patterns, basin sedimentation rates, and provenance history. Likewise, fault conduits influence emplacement of magma chambers in the shallow crust that, upon eruption, can alter drainage and sedimentation patterns and, in the case of large magmatic fields, influence climate. The primary geologic influences on ecosystem evolution, drainage history, water resources quantity and quality, mineral resource, oil and gas potential, and geohazards are universally linked through coupled surface processes, geomorphic evolution, and geodynamics.
Strategy and Approach
This project investigates the geologic framework and evolution of a broad swath of the Southern Rocky Mountains between northern New Mexico and southern Wyoming, focusing on linkages to Cenozoic landscape development. Initial project efforts concentrate on two key areas at opposite ends of the project footprint that have traditionally been viewed as having distinct, contrasting geologic styles and histories:
- Basins and flanking ranges of the northern Rio Grande rift (northern New Mexico and southern Colorado) dominated by Neogene extensional tectonics, volcanism, and sedimentation and the North-Middle Park region (northern Colorado) dominated by Laramide contractional deformation and sedimentation.
- The North-Middle Park region (northern Colorado) dominated by Laramide contractional deformation and sedimentation.
Early focus in these two regions builds on geologic mapping and investigations conducted on predecessor, National Cooperative Geologic Mapping Program-funded Rio Grande Basins and Colorado Headwaters Basin projects. Moreover, these initial project foci will result in detailed and comprehensive datasets to compare "end-member" tectonic influences and histories and allow opportunities to document under-recognized transitional and overprinted tectonic and magmatic signatures and attendant landscape changes. Project efforts will eventually expand to other uplifted mountain blocks and basins (or "parks") to similarly investigate and document their local geologic frameworks and their influences on landscape evolution.
- Maps
- Publications
Below are publications associated with this project.
Filter Total Items: 17Expression of terrain and surface geology in high-resolution helicopter-borne gravity gradient (AGG) data: examples from Great Sand Dunes National Park, Rio Grande Rift, Colorado
Airborne gravity gradient (AGG) data are rapidly becoming standard components of geophysical mapping programs, due to their advantages in cost, access, and resolution advantages over measurements of the gravity field on the ground. Unlike conventional techniques that measure the gravity field, AGG methods measure derivatives of the gravity field. This means that effects of terrain and near-surfaceAuthorsBenjamin J. DrenthLate Miocene-Pleistocene evolution of a Rio Grande rift subbasin, Sunshine Valley-Costilla Plain, San Luis Basin, New Mexico and Colorado
The Sunshine Valley-Costilla Plain, a structural subbasin of the greater San Luis Basin of the northern Rio Grande rift, is bounded to the north and south by the San Luis Hills and the Red River fault zone, respectively. Surficial mapping, neotectonic investigations, geochronology, and geophysics demonstrate that the structural, volcanic, and geomorphic evolution of the basin involves the interminAuthorsC.A. Ruleman, R. A. Thompson, R. R. Shroba, M. Anderson, B. J. Drenth, J. Rotzien, J. LyonPreliminary geologic map of the Bowen Mountain quadrangle, Grand and Jackson Counties, Colorado
The map shows the geology of an alpine region in the southern Never Summer Mountains, including parts of the Never Summer Wilderness Area, the Bowen Gulch Protection Area, and the Arapaho National Forest. The area includes Proterozoic crystalline rocks in fault contact with folded and overturned Paleozoic and Mesozoic sedimentary rocks and Upper Cretaceous(?) and Paleocene Middle Park Formation. TAuthorsJ. C. Cole, William A. Braddock, Theodore R. BrandtBeyond Colorado's Front Range - A new look at Laramide basin subsidence, sedimentation, and deformation in north-central Colorado
This field trip highlights recent research into the Laramide uplift, erosion, and sedimentation on the western side of the northern Colorado Front Range. The Laramide history of the North Park-Middle Park basin (designated the Colorado Headwaters Basin in this paper) is distinctly different from that of the Denver basin on the eastern flank of the range. The Denver basin stratigraphy records the tAuthorsJames C. Cole, James H. Trexler, Patricia H. Cashman, Ian M. Miller, Ralph R. Shroba, Michael A. Cosca, Jeremiah B. WorkmanThe search for Braddock’s Caldera— Guidebook for Colorado Scientific Society Fall 2008 field trip, Never Summer Mountains, Colorado
The report contains the illustrated guidebook that was used for the fall field trip of the Colorado Scientific Society on September 6-7, 2008. It summarizes new information about the Tertiary geologic history of the northern Front Range and the Never Summer Mountains, particularly the late Oligocene volcanic and intrusive rocks designated the Braddock Peak complex. Minor modifications were madeAuthorsJ. C. Cole, Ed Larson, Lang Farmer, Karl S. Kellogg