Metamorphic, magmatic, and tectonic evolution of the central Karakoram in the Biafo-Baltoro-Hushe regions of northern Pakistan

Searle, Michael P.; Rex, A. J.; Tirrul, R.; Rex, D. C.; Barnicoat, A. C.; Windley, B. F.

doi:10.1130/spe232-p47

Cited by 99 publications

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“…U-Pb ages suggest that post-India-Asia collision crustal melting beneath the Hindu Kush is restricted to c. 24 Ma, whereas further east in the Karakoram, the crustal melting record is both more voluminous and more continuous, occurring from c. 37 to c. 9 Ma (Parrish & Tirrul 1989;Searle 1991). Immediately adjacent to the Karakoram in the Nanga Parbat area, there is evidence for crustal melting as young as 1 Ma (Zeitler & Chamberlain 1991;Zeitler et al 1993).…”

Section: The Significance O F Deep Seismicity Beneath the Hindu Kushmentioning

confidence: 99%

“…Note that there is no structural evidence that can distinguish the relative timing of these spatially separated thrusting phases, and consequently the D2 structural category is not subdivided in this study. In the Karakoram, similar deformation styles and associated granite emplacement at 25-21 Ma, indicate the widespread importance of crustal melting along the southern margin of Asia at this time (Parrish & Schfirer et al 1990;Searle & Tirrul 1991;Searle et al 1989Searle et al , 1992.…”

Section: D2 Deformation and Leucogranite Intrusionmentioning

confidence: 99%

“…2), which may have been active only after the Miocene intrusion of the Baltoro and Tangtse granites of the Karakoram batholith at c. 17 Ma; Searle et al (1998). Activity along this fault is thought to have been related to crustal shortening in the Pamir, caused by the continued indentation of India into Asia during and after the late Miocene (Searle 1996;Searle et al 1998). This model is consistent with relating the strikeslip tectonics of the eastern Hindu Kush to the indentation of India, after the c. 24 Ma D2 leucogranite intrusion.…”

Section: Possible Structural Fabric Rotation D1-3 Strike-slip Tectonmentioning

confidence: 99%

“…1), linking up with the Hindu Raj Range and then the Karakoram Range to the east. From the Jurassic, the site of these mountain ranges and the Lhasa block of south Tibet was the southern margin of Asia (Searle 1991). Northward-directed subduction took place along this margin, leading to the accretion of the Kohistan-Ladakh island arc along the Shyok Suture Zone (also called the Northern suture) in the early Late Cretaceous (e.g.…”

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confidence: 99%

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Geological evolution of the Hindu Kush, NW Frontier Pakistan: active margin to continent-continent collision zone

Hildebrand

Searle

Shakirullah

et al. 2000

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A geological map of the eastern Hindu Kush, northwest of Chitral, Northern Pakistan, is presented. The lithologies are placed into two main categories, divided by the Tirich Mir Fault Zone. To the northwest, the units of the eastern Hindu Kush are dominated by monotonous sequences of graphite-rich pelitic rocks. Southeast of the fault, the phyllites and diamictites are thought to be lateral equivalents of the Northern Sedimentary Belt of the Karakoram. A structural analysis of the area studied identifies a major, early deformation phase which is usually characterized by tight to isoclinal folding with a well developed axialplanar schistosity. This deformation is thought to have been related to the northward-directed subduction and accretion beneath the southern margin of Asia during the Mesozoic, and may have taken place over a considerable period of time. A major phase of crustal melting at c. 24 Ma generated migmatites and biotite + muscovite ± garnet ± tourmaline leucogranites (including dykes and the Gharam Chasma pluton). This age is comparable to that of the Baltoro pluton in the Karakoram to the east, confirming the regional importance of crustal melting along the southern margin of the Asian plate during the earliest Miocene. The crustal melting was associated with thrusting and folding of the earlier schistosity. Subhorizontal stretching lineations indicate a phase of strike-slip deformation that is thought to have been associated with anticlockwise rotation of the regional foliation strike from E to NE and N after the emplacement of the Gharam Chasma pluton at c. 24 Ma. This deformation and rotation was probably a direct result of the northward-moving Indian plate forcing Kohistan to indent into Asia, resulting in a left-lateral transpressional tectonic environment which remains today. The anomalous height of the Tirich Mir massif, relative to other peaks in the Hindu Kush and the nearby Hindu Raj, may be accounted for by the onset of this transpression.Intensely active seismicity to depths of 300 km beneath the Hindu Kush is associated with seismic shear wave velocities that are significantly faster than those beneath Tibet, where earthquake occurrence is restricted to the upper crust, and previous geophysical studies indicate elevated thermal conditions and possible crustal melts. U-Pb ages suggest that post-India-Asia collision crustal melting beneath the Hindu Kush is restricted to c. 24 Ma, whereas in the Karakoram, the record is both more voluminous and more continuous from c. 37 to c. 9 Ma. These observations reflect major differences in the thermal histories of these regions, where the relatively cooler conditions beneath the Hindu Kush are associated with continental subduction-related seismicity.

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Section: The Significance O F Deep Seismicity Beneath the Hindu Kushmentioning

confidence: 99%

Section: D2 Deformation and Leucogranite Intrusionmentioning

confidence: 99%

Section: Possible Structural Fabric Rotation D1-3 Strike-slip Tectonmentioning

confidence: 99%

mentioning

confidence: 99%

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Geological evolution of the Hindu Kush, NW Frontier Pakistan: active margin to continent-continent collision zone

Hildebrand

Searle

Shakirullah

et al. 2000

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“…In order to constrain the history of events that produced the KKSZ, most previous studies of the KKSZ have concentrated on the eastern (Dunlap and Wysoczanski, 2002;Searle et al, 1989) and central Karakoram (Fraser et al, 2001;Rex et al, 1988) and much less on the eastern Hindu Kush (Hildebrand et al, 2001). We focused our efforts on obtaining crystallisation ages of plutonic rocks whose structural setting was carefully characterised along the KKSZ of NW Pakistan (Heuberger, 2004).…”

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Age and isotopic constraints on magmatism along the Karakoram-Kohistan Suture Zone, NW Pakistan: evidence for subduction and continued convergence after India-Asia collision

et al. 2007

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Detailed geological mapping in the Drosh-Shishi area in southern Chitral (NW Pakistan) was combined with high-precision U-Pb dating on zircons to constrain the timing of magmatism and associated deformation/metamorphic events related to the Kohistan-Karakoram convergence and collision. Our new ages indicate that the Mesozoic to Tertiary magmatic history of this region is influenced by long-lived melt generation above an active subduction zone. Dated intrusive rocks range in age from 130 to 39 million years, indicating that subduction-related magmatism continued after the Kohistan-Karakoram and the India-Asia collisions. Initial hafnium isotope ratios were measured on the dated zircons to constrain the type of melt source of the dated plutons. The data reveal the different nature of partly coeval magmatism in these units, i.e. continental arc magmatism in the Karakoram (ca. 130-104 Ma) and arc magmatism on the Kohistan side (112-39 Ma). Intrusions within the suture zone can be clearly traced to be Karakoram-derived on the basis of initial Hf isotopic compositions. Granite dykes crosscutting the Kohistan units have sampled an underlying, old continental basement of Gondwana affinity. The geochronological evidence presented in this paper is consistent with Cretaceous subduction beneath the Karakoram Terrane. The related calc-alkaline magmatism seems to have stopped at about 100 Ma. Granite dykes on the Kohistan side show that the magmatic and tectonic history of the KarakoramKohistan Suture Zone continued to the Eocene. This long tectono-metamorphic and magmatic activity in the arc plates was likely due to complex and few million year long interplays between subduction and thrusting events in the forearc, within-arc and back-arc regions between two active subduction zones.

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The geochemical and temporal evolution of the continental lithosphere and its relationship to continental‐scale faulting: The Karakoram Fault, eastern Karakoram, NW Himalayas

Phillips

Searle

Parrish³

2013

Geochem Geophys Geosyst

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New laser ablation multicollector–inductively coupled plasma–mass spectrometry and isotope dilution‐thermal ionization mass spectrometry U‐Pb ages, coupled with Sm‐Nd isotope and geochemical analysis, define the temporal and geochemical evolution of the continental lithosphere in the eastern Karakoram, India, NW Himalaya. Our analysis demonstrates that magmatism occurred between ~108 and 69 Ma and ~22 and 13 Ma. The new age data, coupled with geochemical examination of the granitoids, confirm a parallel evolution with the western Karakoram in Pakistan and supports a model of regional continental crustal thickening and related metamorphism. Middle to Late Cretaceous magmatism immediately adjacent to the Karakoram fault suggests that crustal melting and associated metamorphism are unrelated to shearing along the fault. Miocene leucogranite magmatism occurred almost exactly concomitant with the emplacement of the Baltoro batholith in Pakistan. These trans‐Karakoram leucogranites also display similar geochemical evolution trends. Our new data clearly link the leucogranites along the fault to the regional Baltoro batholith and related metamorphic complexes to the west. This supports previous work suggesting that magmatism and metamorphism were not syn‐kinematic with continental‐scale faulting. The data demonstrate that the Karakoram fault could not have accommodated lateral offset in this region prior to ~16 Ma, limiting the long‐term averaged slip rate to a maximum of ~10 mm/yr.

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Metamorphic, magmatic, and tectonic evolution of the central Karakoram in the Biafo-Baltoro-Hushe regions of northern Pakistan

Cited by 99 publications

References 0 publications

Geological evolution of the Hindu Kush, NW Frontier Pakistan: active margin to continent-continent collision zone

Geological evolution of the Hindu Kush, NW Frontier Pakistan: active margin to continent-continent collision zone

Age and isotopic constraints on magmatism along the Karakoram-Kohistan Suture Zone, NW Pakistan: evidence for subduction and continued convergence after India-Asia collision

The geochemical and temporal evolution of the continental lithosphere and its relationship to continental‐scale faulting: The Karakoram Fault, eastern Karakoram, NW Himalayas

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