A rootless rockies—Support and lithospheric structure of the Colorado Rocky Mountains inferred from CREST and TA seismic data

Hansen, S. M.; Dueker, K. G.; Stachnik, J. C.; Aster, R. C.; Karlstrom, Karl E.

doi:10.1002/ggge.20143

Cited by 70 publications

(98 citation statements)

References 175 publications

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“…They observed east of Yellowstone a faint shallow MLD but no west-dipping structure. Hansen et al (2013) observed the LAB below the Colorado Plateau at 100-150 km depth and east of it at 150-200 km depth. This agrees with our LAB observations along 38 • N (Fig.…”

Section: View On the Discontinuities With Unfilteredmentioning

confidence: 94%

“…Levander and Miller (2012) have mapped the Phanerozoic LAB in the western US. More detailed regional studies in the western United States are published by Rychert et al (2005Rychert et al ( , 2007, Li et al (2007), Hopper et al (2014), Hansen et al (2013), Foster et al (2014 and Lekic and Fischer (2014). Rare observations of the cratonic LAB near about 200 km depth have been obtained by Foster et al (2014) in the US.…”

Section: R Kind Et Al: Structure Of the Upper Mantle From Usarray Smentioning

confidence: 99%

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Structure of the upper mantle in the north-western and central United States from USArray S-receiver functions

et al. 2015

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Abstract. We used more than 40 000 S-receiver functions recorded by the USArray project to study the structure of the upper mantle between the Moho and the 410 km discontinuity from the Phanerozoic western United States to the cratonic central US. In the western United States we observed the lithosphere-asthenosphere boundary (LAB), and in the cratonic United States we observed both the midlithospheric discontinuity (MLD) and the LAB of the craton. In the northern and southern United States the western LAB almost reaches the mid-continental rift system. In between these two regions the cratonic MLD is surprisingly plunging towards the west from the Rocky Mountain Front to about 200 km depth near the Sevier thrust belt. We interpret these complex structures of the seismic discontinuities in the mantle lithosphere as an indication of interfingering of the colliding Farallon and Laurentia plates. Unfiltered S-receiver function data reveal that the LAB and MLD are not single discontinuities but consist of many small-scale laminated discontinuities, which only appear as single discontinuities after longer period filtering. We also observe the Lehmann discontinuity below the LAB and a velocity reduction about 30 km above the 410 km discontinuity.

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Section: View On the Discontinuities With Unfilteredmentioning

confidence: 94%

Section: R Kind Et Al: Structure Of the Upper Mantle From Usarray Smentioning

confidence: 99%

Structure of the upper mantle in the north-western and central United States from USArray S-receiver functions

et al. 2015

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“…Although estimates of crustal thickness show variations of 10 km or more, there is at best a poor correlation of crustal thickness and elevation [e.g., Gilbert, 2012;Gilbert and Sheehan, 2004;Hansen et al, 2013;Levandowski et al, 2014;Sheehan et al, 1995]. On a large scale, Airy isostasy fails in this region [e. g., Sheehan et al, 1995].…”

Section: Moucha Et Almentioning

confidence: 99%

Mantle dynamics, isostasy, and the support of high terrain

2015

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Dynamic topography is commonly understood to be deflection of the Earth's surface that results from convection of the mantle. Because different authors use the words "dynamic topography" differently, topography designated as dynamic may amount to only a few hundred meters or may exceed 2000 m. For most regions, however, surface heights computed on the assumption that the lithospheric column is in isostatic equilibrium provide good approximations to observed topography. The small free-air gravity anomalies and still smaller isostatic anomalies (<~30-50 mGal) associated with long-wavelength topography suggest that deflections of the Earth's surface induced by flow-induced normal tractions applied to the base of the lithosphere do not exceed~300 m. Little evidence exists to show that such tractions support more than~100 m of high terrain in regions like southern Africa, the Rocky Mountains and Colorado Plateau of the USA, eastern Asia, or the Aegean-Anatolian region, where some have argued for many hundreds to >2000 m of dynamic topography. Moreover, simple examples show that if flow-induced stresses maintain a given density distribution, then the resultant surface deflections can be smaller than those that would exist in isostatic equilibrium. In light of confusion over the term "dynamic topography," we offer readers simple tools that we hope will enable them to diagnose the component of topography that results from flow-induced stresses and to distinguish it from topography that is compensated isostatically.

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“…Hundreds of stations and tens of thousands of events distributed throughout the study area provide ample volumetric sampling for highresolution tomographic methods which have previously been applied to image fault and regional structure elsewhere (e.g., Thurber, 2003, Allam andBennington et al, 2013;Allam et al, 2014a). Migration of receiver functions using accurate 3D seismic velocity models has been shown to change interpretations (Gilbert, 2012;Hansen et al, 2013;Ozakin & Ben-Zion, 2015). Finally, fault zone head waves refracting along an interface separating different crustal blocks provide direct evidence for sharp contrasts of seismic velocities across faults (e.g., Ben-Zion, 1989;.…”

Section: Accepted Manuscriptmentioning

confidence: 99%

“…S6). The basic procedure is the same as in Hansen et al (2013). Receiver functions are projected to depth using the 3-D Vp and Vs velocity models from the tomographic inversion in section 2.1.…”

Section: Cross Sections For Moho and Subducted Slab Structurementioning

confidence: 99%

Ten kilometer vertical Moho offset and shallow velocity contrast along the Denali fault zone from double-difference tomography, receiver functions, and fault zone head waves

et al. 2017

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Please cite this article as: A.A. Allam, V. Schulte-Pelkum, Y. Ben-Zion, C. Tape, N. Ruppert, Z.E. Ross , Ten kilometer vertical Moho offset and shallow velocity contrast along the Denali fault zone from double-difference tomography, receiver functions, and fault zone head waves, Tectonophysics (2017Tectonophysics ( ), doi: 10.1016Tectonophysics ( /j.tecto.2017 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.A C C E P T E D M A N U S C R I P T AbstractWe examine the structure of the Denali fault system in the crust and upper mantle using double-difference tomography, P-wave receiver functions, and analysis (spatial distribution and moveout) of fault zone head waves. The three methods have complementary sensitivity; tomography is sensitive to 3D seismic velocity structure but smooths sharp boundaries, receiver functions are sensitive to (quasi) horizontal interfaces, and fault zone head waves are sensitive to (quasi) vertical interfaces. The results indicate that the Mohorovičić discontinuity is vertically offset by 10 to 15km along the central 600km of the Denali fault in the imaged region, with the northern side having shallower Moho depths around 30km. An automated phase picker algorithm is used to identify ~1400 events that generate fault zone head waves only at near-fault stations.At shorter hypocentral distances head waves are observed at stations on the northern side of the fault, while longer propagation distances and deeper events produce head waves on the southern side. These results suggest a reversal of the velocity contrast polarity with depth, which we confirm by computing average 1D velocity models separately north and south of the fault. Using teleseismic events with M>=5.1, we obtain 31,400 P receiver functions and apply common- km to the north. To the east, this offset follows the Totschunda fault, which ruptured during the M7.9 2002 earthquake, rather than the Denali fault itself. The combined results suggest that the Denali fault zone separates two distinct crustal blocks, and that the Totschunda and Hines Creeks segments are important components of the fault and Cretaceous-aged suture zone structure.

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A rootless rockies—Support and lithospheric structure of the Colorado Rocky Mountains inferred from CREST and TA seismic data

Cited by 70 publications

References 175 publications

Structure of the upper mantle in the north-western and central United States from USArray S-receiver functions

Structure of the upper mantle in the north-western and central United States from USArray S-receiver functions

Mantle dynamics, isostasy, and the support of high terrain

Ten kilometer vertical Moho offset and shallow velocity contrast along the Denali fault zone from double-difference tomography, receiver functions, and fault zone head waves

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