Stratigraphy, structure, and tectonic evolution of the Himalayan fold‐thrust belt in western Nepal

DeCelles, Peter G.; Robinson, Delores M.; Quade, Jay; Ojha, T. P.; Garzione, Carmala N.; Copeland, Peter; Upreti, B. N.

doi:10.1029/2000tc001226

Cited by 539 publications

(554 citation statements)

References 72 publications

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“…Details for combinations of velocities, heat production values, and flexural models are in A constant velocity of 17.3 mm/yr using the MCT initiation age of 23 Ma concluded by Long et al (2012) was tested to determine if a generalized long-term rate of shortening can adequately reproduce published cooling ages. This rate is comparable to the ~15-25 mm/yr estimates of modern convergence for the Himalaya (Bilham et al, 1997;Larson et al, 1999;Banerjee and Burgmann, 2002;Zhang et al, 2004;Bettinelli et al, 2006;Banerjee et al, 2008) and long-term rates of shortening through the Himalaya (DeCelles et al, 2001;Lave and Avouac, 2000;Long et al, 2011b). 5…”

Section: Variable Deformation Age and Ratesupporting

confidence: 62%

Testing the effects of topography, geometry and kinematics on modeled thermochronometer cooling ages in the eastern Bhutan Himalaya

Gilmore¹,

McQuarrie²,

Eizenhöfer³

et al. 2017

Preprint

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Abstract. The temporal and kinematic evolution of fold-thrust belts is a critical component for evaluating the viability of proposed plate tectonic, geodynamic and even climatic processes in regions of convergence. Thermochronometer data have the potential to provide temporal constraints, but interpretations of these data are sensitive to both exhumational and deformational processes. In this study, reconstructions of a balanced geologic cross section in the Himalayan fold-thrust belt 10 of eastern Bhutan are used in a flexural and thermal-kinematic model to understand the sensitivity of predicted cooling ages to changes in fault kinematics, geometry and topography. We sequentially deform the cross section with ~10-km deformation steps and apply flexural loading and erosional unloading at each step to develop a high-resolution evolution of deformation, erosion, and burial over time.Comparison of model-predicted cooling ages to published thermochronometer data reveals that cooling ages are most 15 sensitive to (1) location and magnitude of fault ramps, (2) variable shortening rates between 68-6.4 mm/yr, and (3) timing and magnitude of out-of-sequence faulting. The predicted ages are less sensitive to (4) radiogenic heat production, and (5) estimates of topographic evolution. We propose a revised cross section geometry that separates one large ramp previously proposed for the modern decollement into two smaller ramps. The revised cross section results in an improved fit to observed ages, particularly young AFT ages (2-6 Ma) located north of the Main Central Thrust. 20

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Section: Variable Deformation Age and Ratesupporting

confidence: 62%

Testing the effects of topography, geometry and kinematics on modeled thermochronometer cooling ages in the eastern Bhutan Himalaya

Gilmore¹,

McQuarrie²,

Eizenhöfer³

et al. 2017

Preprint

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“…From Figure 9 the basal décollement of the Himalaya thrust belt has an average slope of ~8° and the average  surface slope is =1.5°.  Figure 9 Cross-section of the Himalaya orogen at ~85°E based on [59][60][61][62]65]. Interseismic velocities from [60].…”

Section: Himalaya Of Nepalmentioning

confidence: 99%

“…The discussion is centered on a cross section located in the central Himalaya at ~85°E shown (see Figure 9) that is based on [59][60][61][62].…”

Section: Himalaya Of Nepalmentioning

confidence: 99%

Thick-Skinned and Thin-Skinned Tectonics: A Global Perspective

Pfiffner¹

2017

Preprint

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This paper gives an overview of the large-scale tectonic styles encountered in orogens worldwide. Thin-skinned and thick-skinned tectonics represents two end member styles recognized in mountain ranges. A thick-skinned tectonic style is typical for margins of continental plates. Thick-skinned style including the entire crust and possibly the lithospheric mantle are associated with intracontinental contraction. Delamination of subducting continental crust and horizontal protrusion of upper plate crust into the opening gap occurs in the terminal stage of continent-continent collision. Continental crust thinned prior to contraction is likely to develop relatively thin thrust sheets of crystalline basement. A true thin-skinned type requires a detachment layer of sufficient thickness. Thickness of the décollement layer as well as the mechanical contrast between décollement layer and detached cover control the style of folding and thrusting within the detached cover units. In subduction related orogens, thin-and thick-skinned deformation may occur several hundreds of kilometers from the plate contact zone. Basin inversion resulting from horizontal contraction may lead to the formation of basement uplifts by the combined reactivation of pre-existing normal faults and initiation of new reverse faults. In composite orogens thick-skinned and thin-skinned structures evolve with a pattern where nappe stacking propagates outward and downward.

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“…The combinations of velocities, radiogenic heat production values, and flexural models tested are in Table 3. A constant velocity of 17.3 mm yr −1 using an MCT initiation age of 23 Ma was tested to determine if a generalized long-term rate of shortening can adequately reproduce (Bilham et al, 1997;Larson et al, 1999;Banerjee and Bürgmann, 2002;Zhang et al, 2004;Bettinelli et al, 2006;Banerjee et al, 2008) and long-term rates of shortening for the Himalaya (DeCelles et al, 2001;Lavé and Avouac, 2000;Long et al, 2011b). In Bhutan, variable rates of shortening have been proposed based on the integration of shortening estimates from balanced cross sections with thermochronometer data.…”

Section: Variable Deformation Age and Ratementioning

confidence: 99%

Testing the effects of topography, geometry, and kinematics on modeled thermochronometer cooling ages in the eastern Bhutan Himalaya

et al. 2018

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Abstract. In this study, reconstructions of a balanced geologic cross section in the Himalayan fold-thrust belt of eastern Bhutan are used in flexural-kinematic and thermokinematic models to understand the sensitivity of predicted cooling ages to changes in fault kinematics, geometry, topography, and radiogenic heat production. The kinematics for each scenario are created by sequentially deforming the cross section with ∼ 10 km deformation steps while applying flexural loading and erosional unloading at each step to develop a high-resolution evolution of deformation, erosion, and burial over time. By assigning ages to each increment of displacement, we create a suite of modeled scenarios that are input into a 2-D thermokinematic model to predict cooling ages. Comparison of model-predicted cooling ages to published thermochronometer data reveals that cooling ages are most sensitive to (1) the location and size of fault ramps, (2) the variable shortening rates between 68 and 6.4 mm yr −1 , and (3) the timing and magnitude of out-of-sequence faulting. The predicted ages are less sensitive to (4) radiogenic heat production and (5) estimates of topographic evolution. We used the observed misfit of predicted to measured cooling ages to revise the cross section geometry and separate one large ramp previously proposed for the modern décollement into two smaller ramps. The revised geometry results in an improved fit to observed ages, particularly young AFT ages (2-6 Ma) located north of the Main Central Thrust. This study presents a successful approach for using thermochronometer data to test the viability of a proposed cross section geometry and kinematics and describes a viable approach to estimating the first-order topographic evolution of a compressional orogen.

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Stratigraphy, structure, and tectonic evolution of the Himalayan fold‐thrust belt in western Nepal

Cited by 539 publications

References 72 publications

Testing the effects of topography, geometry and kinematics on modeled thermochronometer cooling ages in the eastern Bhutan Himalaya

Testing the effects of topography, geometry and kinematics on modeled thermochronometer cooling ages in the eastern Bhutan Himalaya

Thick-Skinned and Thin-Skinned Tectonics: A Global Perspective

Testing the effects of topography, geometry, and kinematics on modeled thermochronometer cooling ages in the eastern Bhutan Himalaya

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