Significance of past and recent heat-flow and radioactivity studies in the Southern Rocky Mountains region

Decker, Edward R.; Heasler, Henry P.; Buelow, Kenneth L.; Baker, Keith H.; Hallin, James

doi:10.1130/spe253-p277

Cited by 5 publications

(5 citation statements)

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“…The uplift of both Archean and Proterozoic rock during the Laramide orogeny indicates that the mantle beneath both regions has been modified by orogenic processes. Yet major differences between Archean and Proterozoic lithospheres are still evident today in the Rocky Mountain region based on early results from the Deep Probe experiment (see Snelson et al, this issue), the Rocky Mountain Front Broadband experiment (Lerner-Lam et al, this issue), as well as heat flow data (Decker et al, 1988) and topography. From the cumulative record, we conclude that Archean mantle is remarkably stable, but that it can be modified and even removed under the right conditions.…”

Section: Speculations On Processes Of Litho-sphere Formation and Modimentioning

confidence: 95%

Persistent influence of Proterozoic accretionary boundaries in the tectonic evolution of southwestern North America: Interaction of cratonic grain and mantle modification events

Karlstrom¹,

Humphreys²

1998

Rocky Mountain Geology

198

176

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Northeast-striking tectonic provinces and boundaries were established during 1.8-1.6-Ga assembly of juvenile continental lithosphere in the southwestern United States. This continental grain repeatedly has influenced subsequent intracratonic tectonism and magmatism. After 200 m.y. of stability, cratonic lithosphere was affected by regional, ~1.4-Ga, dominantly granitic magmatism and associated tectonism that reactivated older northeast-striking shear zones in the Proterozoic accreted terranes, but not the Archean lithosphere. In contrast, 1.1-Ga, dominantly mafic magmatism and rifting did not reactivate northeast-striking zones, but occurred along new north-south fracture zones (e.g., Rocky Mountain trend) that reflect cracking of Laurentian lithosphere at a high angle to the Grenville collision. By 500 Ma, rifting had thinned the crust and mantle in the western United States creating the north-south Cordilleran miogeocline. East of the Cordilleran hingeline, isopachs in Lower Paleozoic sedimentary rocks follow northeast-trending structures (Cheyenne belt, Transcontinental arch, and YavapaiMazatzal province boundary), suggesting that older boundaries influenced isostatic response of the craton during thermal subsidence of the margin. Ancestral Rockies and Laramide uplifts and basins did not strongly reactivate northeast-striking boundaries. However, Ancestral Rockies structures end at the Archean-Proterozoic boundary, and Laramide magmatism (Colorado mineral belt) and metallogenic provinces follow northeast-striking Proterozoic boundaries, both suggesting deep-seated lithospheric influences on tectonism.Present mantle structure and topography in the Rocky Mountain region continue to record an interaction between older crustal structures and younger mantle reorganization. Zones of partially molten mantle underlie northeast-striking Proterozoic boundaries (e.g., Snake River Plain, Saint George lineament, and Jemez lineament) and the north-striking Rio Grande rift, and are inferred to record replacement of lithosphere by asthenosphere preferentially along Archean-Proterozoic, Mojave-Yavapai, Yavapai-Mazatzal, and 1.1-Ga lithospheric anisotropies. Highest topography coincides with areas of low-velocity mantle, suggesting an importance of mantle buoyancy in the isostatic balance. Changes in topographic character across ancient crustal boundaries suggests a continued influence of crustal structures in differential uplift and denudation.Inheritance of the Proterozoic northeast grain involves two basic factors: (1) "volumetric" inheritance, in which density and fertility of lithospheric blocks of differing compositions influence isostatic and magmatic response to tectonism; and (2) "interface" inheritance, in which mechanical boundaries are zones of weakness and mass transport. "Volumetric" inheritance is suggested by the distinctive isotopic signatures of different provinces and by the observation that Archean lithosphere has been consistently less fertile for magmas than Proterozoic lithosphere, due to thicker, colder ...

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Section: Speculations On Processes Of Litho-sphere Formation and Modimentioning

confidence: 95%

Persistent influence of Proterozoic accretionary boundaries in the tectonic evolution of southwestern North America: Interaction of cratonic grain and mantle modification events

Karlstrom¹,

Humphreys²

1998

Rocky Mountain Geology

198

176

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“…Durrheim & Mooney, 1994;Karlstrom et _ al., 2002). More recent studies (e.g., Gilbert & Sheehan, 2004;Karlstrom et _ al., 2012) Decker, 1995, andDecker et al, 1988) but without explaining the revision; on this basis a slightly thicker mobile lower-crustal layer would be predicted. We are not aware of any measurement of the heat production in this particular borehole; however the value adopted is similar to others measured in the surrounding region (e.g., Edwards et al, 1978) and the resulting basal heat flow is within the ~34±4 mW m -2 range long considered characteristic of the Great Plains (e.g., Roy et al, 1968;Decker & Smithson, 1975).…”

Section: The Platte River Catchmentmentioning

confidence: 99%

Relation between alternations of uplift and subsidence revealed by Late Cenozoic fluvial sequences and physical properties of the continental crust

Westaway

Bridgland

2014

Boreas

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“…In northern New Mexico and Colorado, the rift is associated with a clearly defined heat flow high. Conductive geotherms calculated from these data suggest geotherms that exceed the crustal solidus above the Moho, requiring convective heat transfer into the crust Decker et al, 1988). In summary, heat flow data clearly define a major geothermal anomaly associated with the Rio Grande rift.…”

Section: Tectonics and Evolutionmentioning

confidence: 93%

The Rio Grande rift: A geological and geophysical overview

Keller

Baldridge

1999

Rocky Mountain Geology

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The Rio Grande rift is a major structural element of the Southern Rocky Mountain region. During the last 20 years this feature has become widely recognized as a major Cenozoic continental rift zone. During this time we have learned much about the structure and evolution of the rift. However, many gaps in our knowledge remain that prevent us from fully understanding its evolution and the processes that formed it. The rift should not be studied in isolation, because the Laramide orogeny, uplift, complex magmatism, and extension that have occurred since the Late Cretaceous are all to some extent related.

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Significance of past and recent heat-flow and radioactivity studies in the Southern Rocky Mountains region

Cited by 5 publications

References 0 publications

Persistent influence of Proterozoic accretionary boundaries in the tectonic evolution of southwestern North America: Interaction of cratonic grain and mantle modification events

Persistent influence of Proterozoic accretionary boundaries in the tectonic evolution of southwestern North America: Interaction of cratonic grain and mantle modification events

Relation between alternations of uplift and subsidence revealed by Late Cenozoic fluvial sequences and physical properties of the continental crust

The Rio Grande rift: A geological and geophysical overview

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