Rheological control on the initial geometry of the Raft River detachment fault and shear zone, western United States

Wells, Michael L.

doi:10.1029/2000tc001202

Cited by 42 publications

(45 citation statements)

References 104 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…12; summary of apatite fi ssion track thermochronology) and to record the progressive unroofi ng of the Raft River detachment during the migration of a rolling hinge from ca. 13.4 to 7 Ma Wells, 2001). The new data from the Raft River Basin allow us to delineate a more detailed history of the Miocene faulting and deposition temporally related to the 13.4-7 Ma low-temperature uplift and cooling history of adjacent footwall rocks.…”

Section: Slip History Of the Albion Fault And Raft River Detachmentmentioning

confidence: 96%

“…In contrast, both the eastern Raft River Mountains and the western fl ank of Middle Mountain (Figs. 3 and 6) expose high-strain quartzites with lower temperature (greenschist facies) mylonitic fabrics formed as a consequence of vertical fl attening and approximately northwest-southeast to east-west stretching and shear (Compton et al, 1977;Wells et al, 2000;Wells, 2001;Strickland et al, 2011aStrickland et al, , 2011b. The 40 Ar/ 39 Ar ages of muscovite, coupled with quartz microstructures indicative of greenschist facies conditions (~350-490 °C; Gottardi et al, 2011), led Wells et al (2000 to interpret that most of the exhumation of the Raft River Mountains occurred along the east-dipping Raft River detachment in the Middle to Late Miocene (15-7 Ma) .…”

Section: Geology and Geochronology Of Footwall Rocks Of The Argmentioning

confidence: 99%

See 1 more Smart Citation

Multistage Cenozoic extension of the Albion–Raft River–Grouse Creek metamorphic core complex: Geochronologic and stratigraphic constraints

et al. 2012

View full text Add to dashboard Cite

Despite numerous studies on the structural evolution of metamorphic core complexes, there is still little consensus on the set and sequence of processes that bring deep levels of the crust to the surface during extension. This problem is partially related to the fact that core complexes expose polydeformed rocks, the history of which has been challenging to decipher. New geochronological and structural data combined with existing data provide improved insight into the Cenozoic extensional evolution of the Albion-Raft River-Grouse Creek (ARG) metamorphic core complex. The Cenozoic extensional history of the core complex can be divided into several distinct stages based on the geochronol ogy and structure of igneous and metamorphic rocks in the lower plate of the complex combined with the geochronology and regional geologic context of sedimentary and volcanic rocks fl anking the complex. Initial volcanism and plutonism was Eocene age (42-34 Ma), related to a regional southwardyounging magmatic event. The development of high-temperature (sillimanite grade) metamorphic fabrics and mineral assemblages in footwall rocks was mostly Oligocene (ca. 32-25 Ma), synchronous with the diapiric rise and intrusion of evolved plutons to midcrustal depths (~10-15 km), formed by partial melting and remobilization of the deeper crust. There is no evidence for associated volcanism or basin development at the surface during this time span. The metamorphic and plutonic rocks of the core complex apparently remained at depth for ~10-12 m.y. until the Middle Miocene (ca. 14 Ma), when they were exhumed by Basin and Range faulting.Detrital zircon studies of continental basin sediments demonstrate that the synextensional Raft River Basin, bounded by the Albion-Raft River fault system, began to develop along the eastern side of the ARG metamorphic core complex ca. 13.5 Ma, synchronous with footwall cooling and uplift between 13.5 and 7 Ma recorded by apatite fi ssion track ages. The evolution of sediment sources in the Raft River Basin help defi ne three phases of Miocene tectonism.(1) Between 13.5 and 10.5 Ma, rapid slip on the Albion fault, which rooted into a ductilebrittle transition zone represented by the Raft River detachment, exhumed Paleozoic strata that, together with Miocene volcanic rocks, sourced the basin. (2) Between 10.5 and 8.2 Ma, continued slip resulted in a topographic depression fi lled with volcanic rocks and detritus derived from footwall metamorphic and crystalline rocks as well as prior sources. (3) After 8.2 Ma, the sedimentary basin was cut, rotated, and repeated by a set of younger north-south-striking normal faults that extended the basin in an east-west direction, structurally uplifting the basin sedi ments to erosion. These younger faults die out to the south and minimally displace the fault system that bounds the metamorphic core of the Raft River Mountains.The Cenozoic evolution proposed for the ARG metamorphic core complex indicates that the formation of Oligocene granitecored gneiss domes and their high-temp...

show abstract

Section: Slip History Of the Albion Fault And Raft River Detachmentmentioning

confidence: 96%

Section: Geology and Geochronology Of Footwall Rocks Of The Argmentioning

confidence: 99%

Multistage Cenozoic extension of the Albion–Raft River–Grouse Creek metamorphic core complex: Geochronologic and stratigraphic constraints

et al. 2012

View full text Add to dashboard Cite

show abstract

“…Moreover, although the ETSZ is currently a contact between a continental unit (Tenda massif) and an oceanic unit (Schiste Lustrés nappe), the formation of the ETSZ is shown here to result from the coalescence of metric to kilometric scale top‐to‐the east shear bands. These geological observations permit thus to disregard the influence of inherited structures, important in other regions such as the Basin and Range [ Wells , 2001]. …”

Section: Introductionmentioning

confidence: 99%

Analysis of continental midcrustal strain localization induced by microfracturing and reaction‐softening

et al. 2003

View full text Add to dashboard Cite

[1] Low-angle extensional shear zones, which often characterize the brittle-ductile transition of the continental crust, are seen here to result from strain localization. The potentially destabilizing deformation mechanism is assumed to be the progressive transformation of fractured coarse feldspar grains into white mica as observed in the East Tenda Shear Zone, Alpine Corsica. The coupling between microfracturing and feldspar-tomica reaction is coeval with strain localization that occurred in that field case at a depth close to 15 km. This reaction is proposed as the main destabilizing factor responsible for the onset of localization, with feldspar having a stationary dislocation creep flow stress larger than mica. To test this hypothesis, a rheological model is constructed based on the field observations for a mixture of three phases-mica, quartz and feldspar-deforming at a common strain rate. The phase concentrations change with time according to the feldspar-to-mica reaction, which takes place only if feldspar grains are fractured, a condition detected with the Mohr-Coulomb criterion. The tendency for the strain to localize is assessed by numerical means for the structure composed of an upper crust gliding rigidly over the lower crust, which sustains an overall simple shear. The onset of strain localization is defined by an increase of at least two orders of magnitude in strain rate over part of the lower crust. The upper crust gliding velocity has to be increased by at least a factor of 5 for localization to occur. The time lapse for this velocity change determines the depth of the shear zone (15-17 km). The kinetics of the metamorphic reaction and the final amount of white mica control its width (1-4 km). The time of the shear zone formation is less than half a million years.

show abstract

“…Both formed at the transition between the thrust belt and hinterland, both lie ~100-150 km east of partly coeval top-to-the-east metamorphic core complexes and developed east of major buried frontal thrust ramps (Fig. 3) (Allmendinger et al, 1983;Coogan and DeCelles, 1996;Rodgers and Janecke, 1992;Wells et al, 2000;Wells, 2001). They have a similar vergence and original geometry.…”

Section: Other Evidence For Slip At Low Angles and Comparison With Thmentioning

confidence: 94%

“…Andersonian fault mechanics with a vertical maximum principal stress does not predict slip on normal faults with dips <30° (Anderson, 1951), and few earthquakes occur on low-angle normal faults (Doser, 1987;Jackson and White, 1989;Wernicke, 1995;Rietbrock et al, 1996;Abers et al, 1997;Sorel, 2000;Boncio et al, 2000). However, the geologic record in areas such as the Basin and Range province of the western United States provides conclusive evidence for past activity on low-angle normal faults (John, 1987;Lister and Davis, 1989;Scott and Lister, 1992;John and Foster, 1993;Axen and Bartley, 1997;Miller and John, 1999;Axen et al, 1999;Wells, 2001).…”

mentioning

confidence: 89%

Excision and the original low dip of the Miocene-Pliocene Bannock detachment system, SE Idaho: Northern cousin of the Sevier Desert detachment?

Carney

Jänecke

2005

Geol Soc America Bull

View full text Add to dashboard Cite

Geologic mapping and structural analysis in the Bannock Range, SE Idaho, indicate that the bulk of Cenozoic extension in southeast Idaho was accommodated by slip on the low-angle Bannock detachment system. The Bannock detachment system consists of lowangle normal faults with a likely N-S extent of >130 km. It was active from ca. 10.3 Ma to ca. 3-4 Ma and accommodated >15 km of top-to-the-WSW extension. The master low-angle detachment fault cuts steeper, older normal faults and extensional folds in its hanging wall.Crosscutting relationships and prior work show that the hanging wall to the detachment system began as a cohesive block that later broke up along normal faults that either sole into or are cut by the master detachment fault. After breakup began, the master detachment fault was folded isostatically by a NNW-trending extensional anticline, the Oxford Ridge anticline. The folding produced a new listric low-angle normal fault east of the Oxford Ridge anticline to replace the back-tilted portion of the detachment fault. This new low-angle normal fault excised part of the hanging wall, cut hanging-wall structures, and served as a secondary breakaway for the detachment. West of the Oxford Ridge anticline, the master detachment fault initiated and slipped at a low angle, is the youngest low-angle normal fault of the system, and has not been rotated to a low-dip angle through time.The exhumed Bannock detachment system, although somewhat smaller, shorter lived, and more disrupted by younger Basin and Range normal faults, is similar to the buried Sevier Desert detachment system beneath central Utah. Both top-to-the-west systems formed near the transition between the Sevier thrust belt and its hinterland, collapsed broad thrust-related culminations eroded to Cambrian rocks, are paired with partly coeval top-to-east metamorphic core complexes ~100-160 km to the west, lie east of major thrust ramps, formed and slipped at low angles in the most extended part of the system, and exhibit a translation and breakup phase of deformation. Both are late Cenozoic in age and have voluminous lacustrine synrift deposits that record saline and alkaline conditions during early extension. Similar processes likely produced both detachment systems.

show abstract

Rheological control on the initial geometry of the Raft River detachment fault and shear zone, western United States

Cited by 42 publications

References 104 publications

Multistage Cenozoic extension of the Albion–Raft River–Grouse Creek metamorphic core complex: Geochronologic and stratigraphic constraints

Multistage Cenozoic extension of the Albion–Raft River–Grouse Creek metamorphic core complex: Geochronologic and stratigraphic constraints

Analysis of continental midcrustal strain localization induced by microfracturing and reaction‐softening

Excision and the original low dip of the Miocene-Pliocene Bannock detachment system, SE Idaho: Northern cousin of the Sevier Desert detachment?

Contact Info

Product

Resources

About