The significance of fission-track ages of apatite in relation to the tectonic history of the Front and Sawatch Ranges, Colorado

Bryant, Bruce; Naeser, Charles W.

doi:10.1130/0016-7606(1980)91<156:tsofao>2.0.co;2

Cited by 52 publications

(35 citation statements)

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“…Elbert and Mt. Massive (Bryant and Naeser, 1980;Shannon and others, 1987;Shannon, 1988). Bryant and Naeser (1980) suggested that the ages reflected westward tilting of the Sawatch Range, with deeply buried apatites having been exposed and cooled relatively later along the east margin of the range.…”

Section: Tectonic Eventsmentioning

confidence: 98%

“…For the most part, this high percentage reflects interest in and studies of ore deposits and related igneous rocks in the area, virtually all of which have proven to be of Tertiary age. However, in addition to dating mineral deposits, the data also provide important information regarding magmatic systems (Bookstrom, 1990;Mutschler and others, 1989) and tectonic events (Bryant and Naeser, 1980;Wallace and Naeser, 1986).…”

Section: Late Cretaceous and Cenozoic Datesmentioning

confidence: 99%

“…Apatite can be used to date these events (Naeser, 1976), and several studies (Bryant and Naeser, 1980;Wallace and Naeser, 1986;Shannon and others, 1987) have focused on uplift and the Cenozoic thermal history of the Sawatch Range. In unmineralized areas of the northern Sawatch Range, apatite dates are scattered but tend to fall into two groups: 56-51 Ma at generally higher elevations, and 46-43 Ma at generally lower elevations around the margins of the Sawatch uplift (Wallace and Naeser, 1986;Shannon and others, 1987;Bryant and Naeser, 1980;Beaty and others, 1990a).…”

Section: Tectonic Eventsmentioning

confidence: 99%

“…In unmineralized areas of the northern Sawatch Range, apatite dates are scattered but tend to fall into two groups: 56-51 Ma at generally higher elevations, and 46-43 Ma at generally lower elevations around the margins of the Sawatch uplift (Wallace and Naeser, 1986;Shannon and others, 1987;Bryant and Naeser, 1980;Beaty and others, 1990a). Zircon and sphene fission-track dates from the Twin Lakes stock are 42 and 46 Ma, respectively (Shannon, 1988).…”

Section: Tectonic Eventsmentioning

confidence: 99%

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Isotopic geochronology of the Leadville 1° x 2° quadrangle, west-central Colorado; summary and discussion

Wallace¹

1995

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Section: Tectonic Eventsmentioning

confidence: 98%

Section: Late Cretaceous and Cenozoic Datesmentioning

confidence: 99%

Section: Tectonic Eventsmentioning

confidence: 99%

Section: Tectonic Eventsmentioning

confidence: 99%

See 2 more Smart Citations

Isotopic geochronology of the Leadville 1° x 2° quadrangle, west-central Colorado; summary and discussion

Wallace¹

1995

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“…ago (Tweto, 1975), the major uplift of the core of the Front Range took place 65 m.y. ago (Bryant and Naeser, 1980). Uranium mineralization clearly accompanied repeated major fault movement in the basement along the range front 70-72 m.y.…”

Section: Trace Elementsmentioning

confidence: 99%

Alteration and vein mineralization, Schwartzwalder uranium deposit, Front Range, Colorado

Wallace¹

1983

Open-File Report

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The Schwartzwalder uranium deposit, in the Front Range west of Denver, Colorado, is the largest vein-type uranium deposit in the United States. The deposit is situated in a steeply dipping fault system that cuts Proterozoic metamorphic rocks. The host rocks represent a submarine volcanic system with associated chert and iron-and sulfide-rich pelitic rocks. Where faulted, the more competent garnetiferous and quartzitic units behaved brittlely and created a deep, narrow conduit.The ores formed 70-72 m.y. ago beneath 3 km of Phanerozoic sedimentary rocks. Mineralization included two episodes of alteration and three stages of vein mineralization. Early carbonatesericite alteration pseudomorphically replaced mafic minerals, whereas the ensuing hematite-adularia episode replaced only the earlier alteration assemblage. Early vein mineralization produced a minor sulfide-adularia-carbonate assemblage. Later vein mineralization generated the uranium ores in two successive stages. Carbonates, sulfides, and adularia filled the remaining voids. Clastic dikes composed of fault gouge and, locally, ore were injected into new and existing fractures.Geologic and chemical evidence suggest that virtually all components of the deposit were derived from major hornblende gneiss units and related rocks. The initial fluids were evolved connate/metamorphic water that infiltrated and resided along the extensive fault zones. Complex fault movements in the frontal zone of the eastern Front Range caused the fluids to migrate to the most permeable segments of the fault zones. Heat was supplied by increased crustal heat flow related to igneous activity in the nearby Colorado mineral belt. Temperatures decreased from 225°C to 125°C during later mineralization, and the pressure episodically dropped from 1000 bars. The CO^ fugacity was initially near 100 bars, and uranium was carried as a dicarbonate complex. Sudden decreases in confining pressure during fault movement caused evolution of 009 and a consequent increase in pH. Uranium was released with destruction of the uranyl complexes; it was subsequently reduced by aqueous sulfur species, thereby leading to the precipitation of pitchblende. ACKNOWLEDGMENTS

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The Application of Fission-Track Dating to the Depositional and Thermal History of Rocks in Sedimentary Basins

Naeser¹,

Naeser²,

McCulloh³

1989

Thermal History of Sedimentary Basins

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The significance of fission-track ages of apatite in relation to the tectonic history of the Front and Sawatch Ranges, Colorado

Cited by 52 publications

References 0 publications

Isotopic geochronology of the Leadville 1° x 2° quadrangle, west-central Colorado; summary and discussion

Isotopic geochronology of the Leadville 1° x 2° quadrangle, west-central Colorado; summary and discussion

Alteration and vein mineralization, Schwartzwalder uranium deposit, Front Range, Colorado

The Application of Fission-Track Dating to the Depositional and Thermal History of Rocks in Sedimentary Basins

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