Early–Middle Eocene Exhumation of the Trans-Himalayan Ladakh Batholith, and the India–Asia Convergence

Kumar, Rajesh; Jain, A. K.; Lal, N.; Singh, Sandeep

doi:10.18520/cs/v113/i06/1090-1098

Cited by 9 publications

(13 citation statements)

References 39 publications

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“…The Indus River flowed through the elevated region in Neogene time eroding the overthrusted Indus basin rocks and producing the observed Miocene cooling signal. Considering cooling from a mean maximum burial temperature of 200°C and assuming a geothermal gradient of 20-30°C/km that is consistent with the regional Miocene geothermal gradients estimated from neighboring lithotectonic units [54][55][56], we infer a removal of~7-10 km of rock from the Indus Group since the onset of Miocene cooling. Chemical weathering and alteration indices and sedimentation rates determined from Indus fan sediments show that erosion peaked in the Himalaya at ca.…”

Section: Discussionsupporting

confidence: 51%

“…Given the timing of key geodynamic, tectonic, and erosional processes that coincide with the timing of Miocene cooling in NW India (Figure 4) and south Tibet, we hypothesize that a combination of these processes played a role in the observed Miocene cooling signal, i.e., the regional Miocene geology supports the thermochronology. In other words, the set of processes controlling cooling in Paleogene time (e.g., [55,59,60]) was different from those controlling cooling in Neogene time. The onset of Miocene cooling on a continental scale is coeval with the regional dynamic surface uplift and a return of northward underthrusting of the Indian plate following Greater India slab breakoff, and both these processes are well documented in south Tibet [24,27].…”

Section: Discussionmentioning

confidence: 99%

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(U-Th)/He Thermochronology of the Indus Group, Ladakh, Northwest India: Is Neogene Cooling a Continental-Scale Thermal Event in the India-Asia Collision Zone?

2021

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The India-Asia continental collision zone archives a sedimentary record of the tectonic, geodynamic, and erosional processes that control the thermal history of the Himalayan orogenic interior since the onset of collision in early Paleogene time. In this paper, we present new (U-Th)/He thermochronometric cooling age data from 18 detrital zircons (ZHe) and 19 detrital apatites (AHe) of the early Eocene–early Miocene (ca. 50–23 Ma) continental facies of the Indus Group along the India-Asia collision zone in Ladakh, northwest (NW) India. This along-strike regional-scale low-temperature thermochronometric data set from the Indus basin is the first report of ZHe and AHe cooling ages from western and eastern Ladakh. Thermal modeling of our ZHe and AHe cooling ages indicates a postdepositional Neogene cooling signal in the Indus Group. Cooling initiated at ca. 21–19 Ma, was operational along the ~300 km strike of the collision zone in NW India by ca. 11 Ma, and continued until ca. 3 Ma. The Miocene cooling signal, also present along the India-Asia collision zone in south Tibet, is a continental-scale cooling event likely linked to increased erosional efficiency by the Indus and Yarlung Rivers across an elevated region resulting from the subduction dynamics of the underthrusting Indian plate.

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Section: Discussionsupporting

confidence: 51%

Section: Discussionmentioning

confidence: 99%

(U-Th)/He Thermochronology of the Indus Group, Ladakh, Northwest India: Is Neogene Cooling a Continental-Scale Thermal Event in the India-Asia Collision Zone?

2021

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“…Based on the geothermal gradient calculated by Zeitler (1985), Sinclair and Jaffey (2001) bracket a 30-50°C/km range for Miocene geothermal gradients in the Indus Basin to estimate exhumation rates of 0.10-0.40 mm/year. However, a 30-50°C/km geothermal gradient range is incompatible with recent studies from the region (e.g., Epard & Steck, 2008;Kumar et al, 2017;Langille et al, 2014;Schlup et al, 2011). Using a bootstrapping algorithm, Kumar et al (2017) modeled a range of geothermal gradients from~22-33°C/km for the Early-Middle Eocene evolution of the Ladakh batholith (Figure 1a) in NW India.…”

Section: Implications and Causes Of Coolingmentioning

confidence: 88%

“…However, a 30-50°C/km geothermal gradient range is incompatible with recent studies from the region (e.g., Epard & Steck, 2008;Kumar et al, 2017;Langille et al, 2014;Schlup et al, 2011). Using a bootstrapping algorithm, Kumar et al (2017) modeled a range of geothermal gradients from~22-33°C/km for the Early-Middle Eocene evolution of the Ladakh batholith (Figure 1a) in NW India. In the Tso Morari Complex to the south (Figure 1a), Eocene-Oligocene geothermal gradients were 18-22°C/km, and the geothermal gradient has remained relatively unperturbed since 30 Ma (Epard & Steck, 2008;Schlup et al, 2011).…”

Section: Implications and Causes Of Coolingmentioning

confidence: 88%

Low‐Temperature Thermochronology of the Indus Basin in Central Ladakh, Northwest India: Implications of Miocene‐Pliocene Cooling in the India‐Asia Collision Zone

et al. 2020

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The India-Asia collision zone in Ladakh, northwest India, records a sequence of tectonothermal events in the interior of the Himalayan orogen following the intercontinental collision between India and Asia in early Cenozoic time. We present zircon fission track, and zircon and apatite (U-Th)/He thermochronometric data from the Indus Basin sedimentary rocks that are exposed along the strike of the collision zone in central Ladakh. These data reveal a postdepositional Miocene-Pliocene (~22-4 Ma) cooling signal along the India-Asia collision zone in northwest India. Our zircon fission track cooling ages indicate that maximum basin temperatures exceeded 200°C but stayed below 280-300°C in the stratigraphically deeper marine and continental strata. Thermal modeling of zircon and apatite (U-Th)/He cooling ages suggests postdepositional basin cooling initiated in Early Miocene time by~22-20 Ma, occurred throughout the basin across zircon (U-Th)/He partial retention temperatures from~20-10 Ma, and continued in the Pliocene time until at least~4 Ma. We attribute the burial of the Indus Basin to sedimentation and movement along the regional Great Counter thrust. The ensuing Miocene-Pliocene cooling resulted from erosion by the Indus River that transects the basin. An approximately coeval cooling signal is well documented east of the study area, along the collision zone in south Tibet. Our new data provide a regional framework upon which future studies can explore the possible interrelationships between tectonic, geodynamic, and geomorphologic factors contributing to Miocene-Pliocene cooling along the India-Asia collision zone from NW India to south Tibet.

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“…Very fast Early-Middle Eocene exhumation of the Trans-Himalayan Ladakh Batholith (LB) is revealed by new Rb-Sr biotite and zircon fission-track ages, when analysed with already published ages on these minerals (Kumar et al, 2018). Exhumation peaked at 3.5 ± 0.9 mm/a between 50-45 Ma (hornblende 40 Ar/ 39 Ar ages) and 48-45 Ma (biotite Rb-Sr ages) because of the India-Asia convergence.…”

Section: Trans-himalayan Tectonic Zonementioning

confidence: 99%

Tectonics of the Western, Sikkim and Arunachal Himalaya

Jain¹,

Thakur²,

Joshi³

et al. 2020

PINSA

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During the period 2016-2020, the Indian scientists undertook extensive research in the Himalayan Orogen, which incorporated extensive field mapping, structural analysis, geochemistry, metamorphic and igneous petrology, stratigraphy and palaeontology, Ar/Ar and U-Pb geochronology, besides low-temperature thermochronology. These activities were almost spread throughout the belt from western sector through Garhwal-Kumaon, Sikkim, Bhutan and Arunachal Pradesh. In addition, research was also undertaken using magnetotelluric methods for large-scale tectonics, seismology, paleoseismology and other disciplines, which are covered in other contributions. National laboratories have now started generating highresolution U-Pb dates, which have been providing impetus to model Himalayan tectonics, besides modelling its Paleoproterozoic and Neoproterozoic configuration.

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Early–Middle Eocene Exhumation of the Trans-Himalayan Ladakh Batholith, and the India–Asia Convergence

Cited by 9 publications

References 39 publications

(U-Th)/He Thermochronology of the Indus Group, Ladakh, Northwest India: Is Neogene Cooling a Continental-Scale Thermal Event in the India-Asia Collision Zone?

(U-Th)/He Thermochronology of the Indus Group, Ladakh, Northwest India: Is Neogene Cooling a Continental-Scale Thermal Event in the India-Asia Collision Zone?

Low‐Temperature Thermochronology of the Indus Basin in Central Ladakh, Northwest India: Implications of Miocene‐Pliocene Cooling in the India‐Asia Collision Zone

Tectonics of the Western, Sikkim and Arunachal Himalaya

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