Structural setting and detrital zircon U–Pb geochronology of Triassic–Cenozoic strata in the eastern Central Pamir, Tajikistan
Published:October 08, 2019
John He, Paul Kapp, James B. Chapman, Peter G. DeCelles, Barbara Carrapa, 2019. "Structural setting and detrital zircon U–Pb geochronology of Triassic–Cenozoic strata in the eastern Central Pamir, Tajikistan", Himalayan Tectonics: A Modern Synthesis, P. J. Treloar, M. P. Searle
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Integration of new geological mapping, detrital zircon geochronology, and sedimentary and metamorphic petrography south of the Muskol metamorphic dome in the Central Pamir terrane provides new constraints on the evolution of the Pamir orogen from Triassic to Late Oligocene time. Zircon U–Pb data show that the eastern Central Pamir includes Triassic strata and mélange that are of Karakul–Mazar/Songpan–Ganzi affinity and comprise the hanging wall of a thrust sheet that may root into the Tanymas Fault c. 35 km to the north. The Triassic rocks are unconformably overlain by Cretaceous strata that bear similarities to coeval units in the southern Qiangtang terrane and the Bangong Suture Zone of central Tibet. Finally, Oligocene or younger conglomerate and interbedded siltstone, the youngest documented strata in the Pamir Plateau proper, record an episode of juvenile magmatism at c. 32 Ma, which is absent in the extant rock record and other detrital compilations from the Pamir but overlaps in age with ultrapotassic volcanic rocks in central Tibet. Zircon Hf isotopic data from the Oligocene grains (εHf(t) ≈ +9.6) suggest a primary mantle contribution, consistent with the hypothesis of Late Eocene lithospheric removal beneath the Pamir Plateau.
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Himalayan Tectonics: A Modern Synthesis
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The Himalaya–Karakoram–Tibet mountain belt resulted from Cenozoic collision of India and Asia and is frequently used as the type example of a continental collision orogenic belt. The last quarter of a century has seen the publication of a remarkably detailed dataset relevant to the evolution of this belt. Detailed fieldwork backed up by state-of-the-art structural analysis, geochemistry, mineral chemistry, igneous and metamorphic petrology, isotope chemistry, sedimentology and geophysics produced a wide-ranging archive of data-rich scientific papers. The rationale for this book is to provide a coherent overview of these datasets in addressing the evolution of the mountain ranges we see today.
This volume comprises 21 specially invited review papers on the Himalaya, Kohistan arc, Tibet, the Karakoram and Pamir ranges. These papers span the history of Himalayan research, chronology of the collision, stratigraphy, magmatic and metamorphic processes, structural geology and tectonics, seismicity, geophysics, and the evolution of the Indian monsoon. This landmark set of papers should underpin the next 25 years of Himalayan research.