The thermochronologic record of erosion and magmatism in the canyonlands region of the Colorado plateau

Kendra E. Murray; Peter W. Reiners; Stuart N. Thomson; Xavier Robert; Kelin X. Whipple

doi:10.2475/05.2019.01

The thermochronologic record of erosion and magmatism in the canyonlands region of the Colorado plateau

Kendra E. Murray, Peter W. Reiners, Stuart N. Thomson, Xavier Robert, Kelin X. Whipple

Earth and Space Exploration, School of (SESE)

Research output: Contribution to journal › Article › peer-review

20 Scopus citations

Abstract

The Cenozoic history of crustal deformation, surface uplift, and erosion of the central Colorado Plateau (southwestern USA) is distinct from and relatively poorly understood compared with surrounding regions in the North American Cordillera, including the Grand Canyon region and the southwestern Plateau margin. Here, we present new apatite thermochronologic results from Paleozoic- Mesozoic sandstones sampled in the Canyonlands region-the interior of the Colorado Plateau in southeastern Utah. The apatite (U-Th-Sm)/He (He) ages are highly dispersed, with both positive-slope and negative-slope age-effective U (eU) trends. Samples with apatite He results suitable for thermal history modeling are from the Abajo and La Sal mountains intrusive complexes and the Permian, Triassic, and Jurassic rocks sampled near the Colorado River at Lees Ferry, Arizona, and Hite, Utah. Samples with the richest thermal history information have positive-slope apatite He age-[eU] trends, with ages ca. 10 to 5 Ma at [eU] < 10 ppm and ca. 25 to 20 Ma at [eU] > 60 ppm. Modeled thermal histories that best predict this pattern require two periods of rock cooling: One during the middle Cenozoic ca. 30 to 20 Ma and the other since the latest Miocene ca. 6 Ma. The most recent cooling documents the transition from a slowly eroding Miocene landscape to recent rapid erosion that likely postdates 6 Ma and the integration of the modern Colorado River. Middle Cenozoic rock cooling can be attributed to either 1 km of erosion between ca. 25 and 15 Ma, as previous workers have suggested in other parts of the Colorado Plateau region, or relaxation of a geothermal gradient transiently doubled by magmatism associated with the vigorous magmatic flare-up that swept through the region ca. 34 to 20 Ma. The ambiguity of using middle Cenozoic rock cooling as a proxy for erosion in this region means that this event should be described using a nongenetic term: The Middle Cenozoic Cooling Event.

Original language	English (US)
Pages (from-to)	339-380
Number of pages	42
Journal	American journal of science
Volume	319
Issue number	5
DOIs	https://doi.org/10.2475/05.2019.01
State	Published - May 2019

Keywords

(U-Th)/He age variability
Apatite thermochronology
Colorado Plateau
Erosion
Flare-up magmatism
Middle Cenozoic rock cooling

ASJC Scopus subject areas

General Earth and Planetary Sciences

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10.2475/05.2019.01

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@article{a933ee1440bc481fa6096906e590dc06,

title = "The thermochronologic record of erosion and magmatism in the canyonlands region of the Colorado plateau",

abstract = "The Cenozoic history of crustal deformation, surface uplift, and erosion of the central Colorado Plateau (southwestern USA) is distinct from and relatively poorly understood compared with surrounding regions in the North American Cordillera, including the Grand Canyon region and the southwestern Plateau margin. Here, we present new apatite thermochronologic results from Paleozoic- Mesozoic sandstones sampled in the Canyonlands region-the interior of the Colorado Plateau in southeastern Utah. The apatite (U-Th-Sm)/He (He) ages are highly dispersed, with both positive-slope and negative-slope age-effective U (eU) trends. Samples with apatite He results suitable for thermal history modeling are from the Abajo and La Sal mountains intrusive complexes and the Permian, Triassic, and Jurassic rocks sampled near the Colorado River at Lees Ferry, Arizona, and Hite, Utah. Samples with the richest thermal history information have positive-slope apatite He age-[eU] trends, with ages ca. 10 to 5 Ma at [eU] < 10 ppm and ca. 25 to 20 Ma at [eU] > 60 ppm. Modeled thermal histories that best predict this pattern require two periods of rock cooling: One during the middle Cenozoic ca. 30 to 20 Ma and the other since the latest Miocene ca. 6 Ma. The most recent cooling documents the transition from a slowly eroding Miocene landscape to recent rapid erosion that likely postdates 6 Ma and the integration of the modern Colorado River. Middle Cenozoic rock cooling can be attributed to either 1 km of erosion between ca. 25 and 15 Ma, as previous workers have suggested in other parts of the Colorado Plateau region, or relaxation of a geothermal gradient transiently doubled by magmatism associated with the vigorous magmatic flare-up that swept through the region ca. 34 to 20 Ma. The ambiguity of using middle Cenozoic rock cooling as a proxy for erosion in this region means that this event should be described using a nongenetic term: The Middle Cenozoic Cooling Event.",

keywords = "(U-Th)/He age variability, Apatite thermochronology, Colorado Plateau, Erosion, Flare-up magmatism, Middle Cenozoic rock cooling",

author = "Murray, {Kendra E.} and Reiners, {Peter W.} and Thomson, {Stuart N.} and Xavier Robert and Whipple, {Kelin X.}",

note = "Funding Information: KEM acknowledges support from an NSF GRFP award, an ARCS Phoenix Chapter Prentice Scholarship, a GSA student research grant, and a P.E.O. Scholar Award. A summer scholarship from ConocoPhilips through UA Geosciences funded fieldwork. NSF-EAR 1338583 supports the Arizona LaserChron Center. XR was supported by a CIFAR Postdoctoral Fellowship. Thanks to Ryan Porter for discussions of geophysical evidence for mid-Cenozoic magmatism in the central Colorado Plateau region and to Jay Quade, George Davis, and Mihai Ducea for comments on early versions of the manuscript. We thank Matthew Dettinger and Jordan Holsapple for assistance in the field. Uttam Chowdhury, Erin Abel, and Nicky Geisler assisted in the lab. We acknowledge thorough and constructive reviews from Joel Pederson, Karl Karlstrom, one anonymous reviewer, and the editors at American Journal of Science. Publisher Copyright: {\textcopyright} 2019 American Journal of Science. All rights reserved.",

year = "2019",

month = may,

doi = "10.2475/05.2019.01",

language = "English (US)",

volume = "319",

pages = "339--380",

journal = "American journal of science",

issn = "0002-9599",

publisher = "Yale University",

number = "5",

}

TY - JOUR

T1 - The thermochronologic record of erosion and magmatism in the canyonlands region of the Colorado plateau

AU - Murray, Kendra E.

AU - Reiners, Peter W.

AU - Thomson, Stuart N.

AU - Robert, Xavier

AU - Whipple, Kelin X.

N1 - Funding Information: KEM acknowledges support from an NSF GRFP award, an ARCS Phoenix Chapter Prentice Scholarship, a GSA student research grant, and a P.E.O. Scholar Award. A summer scholarship from ConocoPhilips through UA Geosciences funded fieldwork. NSF-EAR 1338583 supports the Arizona LaserChron Center. XR was supported by a CIFAR Postdoctoral Fellowship. Thanks to Ryan Porter for discussions of geophysical evidence for mid-Cenozoic magmatism in the central Colorado Plateau region and to Jay Quade, George Davis, and Mihai Ducea for comments on early versions of the manuscript. We thank Matthew Dettinger and Jordan Holsapple for assistance in the field. Uttam Chowdhury, Erin Abel, and Nicky Geisler assisted in the lab. We acknowledge thorough and constructive reviews from Joel Pederson, Karl Karlstrom, one anonymous reviewer, and the editors at American Journal of Science. Publisher Copyright: © 2019 American Journal of Science. All rights reserved.

PY - 2019/5

Y1 - 2019/5

N2 - The Cenozoic history of crustal deformation, surface uplift, and erosion of the central Colorado Plateau (southwestern USA) is distinct from and relatively poorly understood compared with surrounding regions in the North American Cordillera, including the Grand Canyon region and the southwestern Plateau margin. Here, we present new apatite thermochronologic results from Paleozoic- Mesozoic sandstones sampled in the Canyonlands region-the interior of the Colorado Plateau in southeastern Utah. The apatite (U-Th-Sm)/He (He) ages are highly dispersed, with both positive-slope and negative-slope age-effective U (eU) trends. Samples with apatite He results suitable for thermal history modeling are from the Abajo and La Sal mountains intrusive complexes and the Permian, Triassic, and Jurassic rocks sampled near the Colorado River at Lees Ferry, Arizona, and Hite, Utah. Samples with the richest thermal history information have positive-slope apatite He age-[eU] trends, with ages ca. 10 to 5 Ma at [eU] < 10 ppm and ca. 25 to 20 Ma at [eU] > 60 ppm. Modeled thermal histories that best predict this pattern require two periods of rock cooling: One during the middle Cenozoic ca. 30 to 20 Ma and the other since the latest Miocene ca. 6 Ma. The most recent cooling documents the transition from a slowly eroding Miocene landscape to recent rapid erosion that likely postdates 6 Ma and the integration of the modern Colorado River. Middle Cenozoic rock cooling can be attributed to either 1 km of erosion between ca. 25 and 15 Ma, as previous workers have suggested in other parts of the Colorado Plateau region, or relaxation of a geothermal gradient transiently doubled by magmatism associated with the vigorous magmatic flare-up that swept through the region ca. 34 to 20 Ma. The ambiguity of using middle Cenozoic rock cooling as a proxy for erosion in this region means that this event should be described using a nongenetic term: The Middle Cenozoic Cooling Event.

AB - The Cenozoic history of crustal deformation, surface uplift, and erosion of the central Colorado Plateau (southwestern USA) is distinct from and relatively poorly understood compared with surrounding regions in the North American Cordillera, including the Grand Canyon region and the southwestern Plateau margin. Here, we present new apatite thermochronologic results from Paleozoic- Mesozoic sandstones sampled in the Canyonlands region-the interior of the Colorado Plateau in southeastern Utah. The apatite (U-Th-Sm)/He (He) ages are highly dispersed, with both positive-slope and negative-slope age-effective U (eU) trends. Samples with apatite He results suitable for thermal history modeling are from the Abajo and La Sal mountains intrusive complexes and the Permian, Triassic, and Jurassic rocks sampled near the Colorado River at Lees Ferry, Arizona, and Hite, Utah. Samples with the richest thermal history information have positive-slope apatite He age-[eU] trends, with ages ca. 10 to 5 Ma at [eU] < 10 ppm and ca. 25 to 20 Ma at [eU] > 60 ppm. Modeled thermal histories that best predict this pattern require two periods of rock cooling: One during the middle Cenozoic ca. 30 to 20 Ma and the other since the latest Miocene ca. 6 Ma. The most recent cooling documents the transition from a slowly eroding Miocene landscape to recent rapid erosion that likely postdates 6 Ma and the integration of the modern Colorado River. Middle Cenozoic rock cooling can be attributed to either 1 km of erosion between ca. 25 and 15 Ma, as previous workers have suggested in other parts of the Colorado Plateau region, or relaxation of a geothermal gradient transiently doubled by magmatism associated with the vigorous magmatic flare-up that swept through the region ca. 34 to 20 Ma. The ambiguity of using middle Cenozoic rock cooling as a proxy for erosion in this region means that this event should be described using a nongenetic term: The Middle Cenozoic Cooling Event.

KW - (U-Th)/He age variability

KW - Apatite thermochronology

KW - Colorado Plateau

KW - Erosion

KW - Flare-up magmatism

KW - Middle Cenozoic rock cooling

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The thermochronologic record of erosion and magmatism in the canyonlands region of the Colorado plateau

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