Late Cretaceous stratigraphy, deformation, and intrusion in the Madison Range of southwestern Montana

Tysdal, R.G.; Marvin, Richard F.; DeWitt, Ed

doi:10.1130/0016-7606(1986)97<859:lcsdai>2.0.co;2

Cited by 17 publications

(18 citation statements)

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“…During 70 million to 65 million years ago (latest Cretaceous), it predicts a belt of slow shortening that extends from western Montana south through Utah to eastern Arizona. This corresponds nicely to some of the more western Laramnide structures: the Blacktail-Snowcrest and Madison ranges in Montana were formed in the latest Cretaceous (24,25), and thrust faulting in southern Arizona is also partly Cretaceous in age (26). The central part of this belt overlaps the preexisting Overtrust Belt from the waning Sevier orogeny, which in fact experienced its last major shortening about 70 million years ago (27).…”

Section: Comparison To Geologic Historysupporting

confidence: 62%

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Formation of the Rocky Mountains, Western United States: A Continuum Computer Model

Bird

1988

Science

336

280

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One hypothesis for the information of the Rocky Mountain structures in late Cretaceous through Eocene time is that plate of oceanic lithosphere was underthrust horizontally along the base of the North American lithosphere. The horizontal components of the motion of this plate are known from paleomagnetism, and the edge of the region of flat slab can estimated from reconstructed patterns of volcanism. New techniques of finite-element modeling allow prediction of the thermal and mechanical effects of horizontal subduction on the North American plate. A model that has a realistic temperature-dependent rheology and a simple plane-layered initial condition is used to compute the consequences of horizontal underthrusting in the time interval 75 million to 30 million years before present. Successful prediction of this model include (i) the location, amount, and direction of horizontal shortening that has been inferred from Laramide structures; (ii) massive transport of lower crust from southwest to northeast; (iii) the location and timing of the subsequent extension in metamorphic core complexes and the Rio Grande rift; and (iv) the total area eventually involved in Basin-and-Range style extension. In a broad sense, this model has predicted the belt of Laramide structures, the transport of crust from the coastal region to the continental interior, the subsequent extension in metamorphic core complexes and the Rio Grande rift, and the geographic region of late Tertiary Basin-and-Range extension. Its principal defects are that (i) many events are predicted about 5 million to 10 million years too late and (ii) the wave of crustal thickening does not travel far enough to the east. Reasonable modifications to the oceanic plate kinematics and rheologies that were assumed may correct these defects. The correspondence of model predictions to actual geology is already sufficiently close to show that the hypothesis that horizontal subduction caused the Laramide orogeny is probably correct. The Rocky Mountain thrust and reverse faults formed in an environment of east-west to northeast-southwest compressive stress that was caused by the viscous coupling between the oceanic plate and the base of the North American crust. Nonuniform crustal thickening by simple-shear transport also caused relative uplifts; therefore, this model is consistent with both of the range-forming mechanisms that have been inferred (1). A new proposal that arises from this simulation is that horizontal subduction also caused the subsequent extensional Basin-and-Range taphrogeny by stripping away the mantle lithosphere so that the crust was exposed to hot asthenosphere after the oceanic slab dropped away.

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Section: Comparison To Geologic Historysupporting

confidence: 62%

“…This suggests that removal oflithosphere by horizontal subduction is the key factor that controls the extent and timing of the Basin-and-Range taphrogeny. 25 MARCH I988…”

Section: Comparison To Geologic Historymentioning

confidence: 99%

Formation of the Rocky Mountains, Western United States: A Continuum Computer Model

Bird

1988

Science

336

280

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“…At the site of the present study in and near the Madison Range, ~35 km east of the Blacktail-Snowcrest uplift, the onset of deformation and volcanism was synchronous with the ~79-Ma basal deposits of the Upper Cretaceous Livingston Formation (Tysdal, 1990) and continued during deposition of the Upper Cretaceous Sphinx Conglomerate, which contains an unroofing sequence of clasts (becoming older stratigraphically upwards) shed from the hanging wall of the Hillgard thrust system (DeCelles et al, 1987). Deformation had essentially ceased by latest Cretaceous time (~69 Ma), the apparent age of the dacite sills and dikes that intrude both the Sphinx Conglomerate and the thrusts of the Hillgard thrust system (Tysdal et al, 1986, and this study). Farther east and south, in the ancestral Teton, Gros Ventre, and Wind River Ranges of Wyoming, Laramide deformation began in Late Cretaceous time and continued through most of the Paleocene (Dorr et al, 1977;Perry et al, 1992).…”

Section: Figurementioning

confidence: 63%

“…1) (Kellogg and Williams, 2000). Previous studies showed that one sill, dated at 68-69 Ma, intrudes Laramide thrust planes of the Hilgard thrust system, suggesting that thrusting ceased by latest Cretaceous time (Tysdal et al, 1986). However, it is possible that sill injection accompanied early thrusting and associated folding, as paleomagnetic directions from Late Cretaceous (~77 Ma) sills along the southern margin of the Helena salient of the Montana thrust belt in the Jefferson Canyon Traverse Zone have been shown to pre-date Laramide thrusting (Harlan et al, 2002;Harlan et al, unpublished data).…”

Section: Paleomagnetic Analysismentioning

confidence: 98%

New 40Ar/39Ar age determinations and paleomagnetic results bearing on the tectonic and magmatic history of the northern Madison Range and Madison Valley region, southwestern Montana, U.S.A.

Kellogg¹,

Harlan²

2007

Rocky Mountain Geology

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Detailed 40 Ar/ 39 Ar dating and paleomagnetic analysis of dacite porphyry sills and dikes that intrude Cretaceous sedimentary rocks in the northern Madison Range in southwestern Montana show that Laramide shortening was essentially complete by ~69 Ma. A negative paleomagnetic fold test indicates that Laramide folding occurred before cooling of the dacite sills and dikes at ~69 Ma. Laramide deformation began synchronous with deposition of the Livingston Formation rocks at ~79 Ma. These results are consistent with previous observations in the region that show the onset of Laramide deformation in the northern Rocky Mountains becoming progressively younger toward the east. 40 Ar/ 39 Ar dating of additional igneous rocks in the northern Madison Valley and around Norris, Montana better define post-Laramide tectonomagmatic events in the region, including Eocene-Oligocene volcanism and Basin and Range crustal extension. Dates from three rhyolitic intrusions near Red Mountain are between 48.71 ± 0.18 Ma and 49.42 ± 0.18 Ma, similar to the dates from basal silicic flows of the Virginia City volcanic field (part of the southwest Montana volcanic province), suggesting that the Red Mountain intrusions may have been the sources for some of the early extrusive rocks. Magmatism in the Virginia City volcanic field became generally more mafic with time, and a ~30-Ma basalt flow near Norris is considered a late, outlying member of the volcanic field. A tuff along the east side of the Madison Valley half graben yielded a early middle Miocene date (16.2 ± 0.19 Ma), suggesting that accelerated crustal extension and associated rapid basin sedimentation probably began in the early Miocene, slightly earlier than previous estimates.

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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). The sampling area in the Livingston Formation is adjacent to the northem flank of the Beartooth Range, a Laramide foreland uplift block.…”

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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Late Cretaceous stratigraphy, deformation, and intrusion in the Madison Range of southwestern Montana

Cited by 17 publications

References 0 publications

Formation of the Rocky Mountains, Western United States: A Continuum Computer Model

Formation of the Rocky Mountains, Western United States: A Continuum Computer Model

New 40Ar/39Ar age determinations and paleomagnetic results bearing on the tectonic and magmatic history of the northern Madison Range and Madison Valley region, southwestern Montana, U.S.A.

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

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