Preliminary stratigraphic and structural architecture of Bhutan: Implications for the along strike architecture of the Himalayan system

McQuarrie, Nadine; Robinson, Delores M.; Long, Sean P.; Tobgay, Tobgay; Grujić, Djordje; Gehrels, George E.; Ducea, Mihai N.

doi:10.1016/j.epsl.2008.04.030

Cited by 273 publications

(279 citation statements)

References 60 publications

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“…The 500 Ma grains may have been locally derived in association with widespread granitic intrusion around the margin of Gondwanaland, including India LeFort et al 1986;Cawood, Johnson & Nemchin, 2007). McQuarrie et al (2008) provided a detrital zircon spectrum from their sample BU07-1 from the 'Chekha Formation' collected from the Ura klippe to the east of the Wachi La. The spectrum is similar to those in our Wachi La samples, except that it lacks grains younger than approximately 800 Ma.…”

Section: Detrital Zircon Geochronologymentioning

confidence: 80%

“…1) shows the Chekha Series to be exposed in what has since been recognized as the area containing both the Tang Chu klippe and the Black Mountain outlier. This view has since been extended to include outcrops of the Chekha Formation in all the Bhutanese outliers and in the Tethyan Himalaya (Grujic, Hollister & Parrish, 2002;McQuarrie et al 2008;Chakungal et al 2010;Long & McQuarrie, 2010). In effect, the term 'Chekha Formation' has become the default stratigraphic name for all sedimentary rocks within the outliers unless they are distinguished by the presence of age-diagnostic fossils.…”

Section: B the Chekha Formation And Its Stratigraphic Relationshipmentioning

confidence: 99%

“…Sedimentary rocks that lack grains of about 500 Ma were thus likely deposited more than 515 Ma ago. McQuarrie et al's (2008) sample NBH-7 lacks grains younger than about 850 Ma, and given the abundance of young Neoproterozoic grains in every published Cambrian sample in the Himalaya, was likely deposited significantly earlier in the Neoproterozoic. Hence we disagree with McQuarrie et al (2008, p. 112) in viewing the age of the Baxa Group as entirely Cambrian or younger.…”

Section: Detrital Zircon Geochronologymentioning

confidence: 99%

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Cambrian rocks and faunas of the Wachi La, Black Mountains, Bhutan

et al. 2010

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-The Pele La Group in the Wachi La section in the Black Mountains of central Bhutan represents the easternmost exposure of Cambrian strata known in the Himalaya. The group contains a succession of siliciclastic rocks with minor amounts of carbonate, the uppermost unit of which, the Quartzite Formation, bears age-diagnostic trilobite body fossils that are approximately 493 Ma old. Trilobite species include Kaolishania granulosa, Taipaikia glabra and the new species Lingyuanaspis sangae. A billingsellid brachiopod, Billingsella cf. tonkiniana, is co-occurrent. This fauna is precisely correlated with that of a specific stratigraphic horizon within the upper part of the Kaolishania Zone, Stage 9 of the Cambrian System, Furongian Epoch of the North China block, and thus represents the youngest Cambrian sedimentary rocks yet known from the Himalaya. The faunal similarity suggests proximity between North China and the Himalayan margin at this time. This unit was deposited in a predominantly storm-influenced shelf and shoreface environment. U-Pb geochronological data from detrital zircon grains from the fossil-bearing beds of the Quartzite Formation and strata of the underlying Deshichiling Formation show grain age spectra consistent with those from Cambrian rocks of the Lesser and Tethyan Himalaya in Tibet, India and Pakistan. These data support continuity of the northern Gondwanan margin across the Himalaya. Prominent peaks of approximately 500 Ma zircons in both the Quartzite and Deshichiling formations are consistent with the Furongian (late Cambrian) age assignment for these strata. The presence of these relatively young zircon populations implies rapid post-cooling erosion of igneous bodies and subsequent deposition which may reflect the influence of a widespread Cambro-Ordovician orogenic event evident in the western Himalaya.

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Section: Detrital Zircon Geochronologymentioning

confidence: 80%

Section: B the Chekha Formation And Its Stratigraphic Relationshipmentioning

confidence: 99%

Section: Detrital Zircon Geochronologymentioning

confidence: 99%

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Cambrian rocks and faunas of the Wachi La, Black Mountains, Bhutan

et al. 2010

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“…North of these units, multiple fault-bound packages of the Neoproterozoic-Cambrian Baxa Group are repeated in the upper Lesser Himalayan duplex. The Shumar Thrust (ST), exposed immediately to the north, is interpreted as the roof thrust of the system (McQuarrie et al, 2008;Long et al, 2011b). In the hanging wall of the Shumar Thrust, the Paleoproterozoic Daling-Shumar Group is overlain by the stratigraphically unconformable Neoproterozoic-Ordovician Jashidanda Formation.…”

Section: Tectonostratigraphymentioning

confidence: 99%

“…In the hanging wall of the Shumar Thrust, the Paleoproterozoic Daling-Shumar Group is overlain by the stratigraphically unconformable Neoproterozoic-Ordovician Jashidanda Formation. These strata are repeated multiple times to form the lower Lesser Himalayan duplex with the Main Central Thrust (MCT) as the roof thrust (McQuarrie et al, 2008;Long et al, 2011a, b).…”

Section: Tectonostratigraphymentioning

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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Geometry and kinematics of the Main Himalayan Thrust and Neogene crustal exhumation in the Bhutanese Himalaya derived from inversion of multithermochronologic data

Coutand

Whipp

Grujić

et al. 2014

J. Geophys. Res. Solid Earth

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117

257

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Both climatic and tectonic processes affect bedrock erosion and exhumation in convergent orogens, but determining their respective influence is difficult. A requisite first step is to quantify long-term (~10 6 year) erosion rates within an orogen. In the Himalaya, past studies suggest long-term erosion rates varied in space and time along the range front, resulting in numerous tectonic models to explain the observed erosion rate distribution. Here, we invert a large data set of new and existing thermochronological ages to determine both long-term exhumation rates and the kinematics of Neogene tectonic activity in the eastern Himalaya in Bhutan. New data include 31 apatite and five zircon (U-Th)/He ages, and 49 apatite and 16 zircon fission-track ages along two north-south oriented transects across the orogen in western and eastern Bhutan. Data inversion was performed using a modified version of the 3-D thermokinematic model Pecube, with parameter ranges defined by available geochronologic, metamorphic, structural, and geophysical data. Among several important observations, our three main conclusions are as follows: (1) Thermochronologic ages do not spatially correlate with surface traces of major fault zones but appear to reflect the geometry of the underlying Main Himalayan Thrust; (2) our data are compatible with a strong tectonic influence, involving a variably dipping Main Himalayan Thrust geometry and steady state topography; and (3) erosion rates have remained constant in western Bhutan over the last~10 Ma, while a significant decrease occurred at~6 Ma in eastern Bhutan, which we partially attribute to convergence partitioning into uplift of the Shillong Plateau.

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Preliminary stratigraphic and structural architecture of Bhutan: Implications for the along strike architecture of the Himalayan system

Cited by 273 publications

References 60 publications

Cambrian rocks and faunas of the Wachi La, Black Mountains, Bhutan

Cambrian rocks and faunas of the Wachi La, Black Mountains, Bhutan

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

Geometry and kinematics of the Main Himalayan Thrust and Neogene crustal exhumation in the Bhutanese Himalaya derived from inversion of multithermochronologic data

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