Origin and structure of the Livingston igneous rocks, Montana

Parsons, Willard H.

doi:10.1130/gsab-53-1175

Cited by 7 publications

(7 citation statements)

References 3 publications

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“…These sedimentary rocks are overlain by at least 300 m of clast-supported lahar deposits ( fig. 3) composed of poorly sorted, bouldery mudflows correlative with the Livingston Group (Parsons, 1942;p. 1177).…”

Section: Physical Volcanology Of the Sliderock Mountain Volcanomentioning

confidence: 99%

“…These rocks are important in understanding the geologic and tectonic setting of the northern Rocky Mountains because they constitute one of the easternmost Late Cretaceous volcanic fields in the North American Cordillera. The volcanic, volcaniclastic, and intrusive rocks that comprise this field have been described by a number of workers including Weed (1893), Vhay (1934), Rouse and others (1937), Parsons (1942), and Brozdowski (1983), but in general, modern petrologic, geochemical, and geochronologic data are lacking for these rocks. In this report, we present new geologic, petrologic, geochemical, and 40Ar/39Ar geochronologic data from the informally named Sliderock Mountain volcano, one of the main volcanic centers in this field.…”

Section: Introduction and Geologic Settingmentioning

confidence: 99%

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Geology, age, and tectonic setting of the Cretaceous Sliderock Mountain Volcano, Montana

Bray¹,

Harlan²

1998

Professional Paper

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Section: Physical Volcanology Of the Sliderock Mountain Volcanomentioning

confidence: 99%

Section: Introduction and Geologic Settingmentioning

confidence: 99%

Geology, age, and tectonic setting of the Cretaceous Sliderock Mountain Volcano, Montana

Bray¹,

Harlan²

1998

Professional Paper

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“…The Livingston and Maudlow Formations of southwest Montana (Figure 2) were chosen for study because their location to the east of the most disturbed part of the western Cordillera should produce undisturbed cratonic magnetizations, and the ages assigned to the formations are latest Cretaceous (Parsons, 1942;Marvin and Dobson, 1979;Langston, 1985;Skipp and McGrew, 1977;Skipp and Peterson, 1965;Vhay, 1939 were taken from andesitic to dacitic welded tuffs or lapilli-tuffs in the lower part of the formation (Langston, 1985;Parsons, 1942;Vhay, 1939). The rocks are Campanian in age, based on stratigraphic correlation with sedimentary rocks in the basin, and a radiometric date of 79.8 +_ 2.9 Ma (Tysdal et al, 1986).…”

Section: G•logic Settingmentioning

confidence: 99%

Paleomagnetic results from the Upper Cretaceous Maudlow and Livingston formations, southwest Montana

Swenson

McWilliams

1989

Geophysical Research Letters

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A paleomagnetic investigation of welded tuff units from the Late Cretaceous Livingston and Maudlow Formations was undertaken to refine the Late Cretaceous to Paleocene APWP for cratonic North America. After progressive AF and thermal demagnetization, the Maudlow Formation (46.1°N, 248.9°E) yields a paleomagnetic pole at 70°N, 208°E (11 sites, A95 = 9°, K = 22). Tectonic correction improves the directional grouping, and the change is statistically significant. Two normal polarity intervals bounding a single reversed polarity interval are present. We interpret the reversed interval to be Chron 33r, on the basis of: [1] stratigraphic correlation of the Maudlow Formation with the Campanian Sedan Formation located 40 km to the east, and [2] K‐Ar dates of 83 ± 2 Ma at the middle of the sampled section and 74.9 ± 1 Ma near the top of the sampled section. The Livingston Formation (45.5°N, 250.1°E) yields a high Hc magnetization with a negative fold test, suggesting a post‐folding secondary magnetization. The Livingston mean direction yields a paleomagnetic pole at 72°N, 218°E (10 sites, A95 = 4°, K = 107) and is clearly distinguishable from a co‐existing lower Hc component reflecting a recent viscous overprint. We interpret the high Hc magnetization as Late Cretaceous to Paleocene in age. Neither the Maudlow Formation pole nor the pole derived from the high Hc overprint in the Livingston Formation agree with previously published poles for either the Late Cretaceous or Tertiary, but they do lie on a simple continuation of the APWP between Late Cretaceous and Paleocene mean poles. Secondary magnetizations found in the Franciscan Complex of California also yield poles which lie on a proposed extension of the APWP. If the Franciscan secondary poles represent an overprint event associated with early Tertiary accretion, and if the Livingston secondary pole represents a deformational event related to Laramide uplift of the nearby Beartooth Range, then together these three poles suggest that the North American APWP may continue farther to the east and south to define a Cretaceous‐Tertiary cusp.

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“…The writer at first thought that these rocks might be approximately equivalent to the Livingston formation of central Montana, which contains a large amount of andesitic tuff, agglomerate, and breccia (Weed, 1893, pp. 21-27;Parsons, 1942Parsons, , pp. 1175Parsons, -1186.…”

Section: Volcanic Debris In Cretaceous Rocksmentioning

confidence: 99%

A geologic reconnaissance of parts of Beaverhead and Madison Counties, Montana

Klepper¹

1950

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Origin and structure of the Livingston igneous rocks, Montana

Cited by 7 publications

References 3 publications

Geology, age, and tectonic setting of the Cretaceous Sliderock Mountain Volcano, Montana

Geology, age, and tectonic setting of the Cretaceous Sliderock Mountain Volcano, Montana

Paleomagnetic results from the Upper Cretaceous Maudlow and Livingston formations, southwest Montana

A geologic reconnaissance of parts of Beaverhead and Madison Counties, Montana

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