Building the Hindu Kush: monazite records of terrane accretion, plutonism and the evolution of the Himalaya–Karakoram–Tibet orogen

Abstract

In situ U-Th/Pb (LA-ICP-MS) monazite ages from the Hindu Kush of NW Pakistan provide new petrochronologic constraints on the tectonic evolution of the Himalaya-Karakoram-Tibet orogen. Monazites from two adjacent garnet + staurolite schist specimens yield multiple age populations that record the major Mesozoic and Cenozoic deformational, magmatic and metamorphic events along the southern margin of Eurasia. These include the accretion of the Hindu Kush-SW Pamir to Eurasia during the Late Triassic, followed by the accretion of the Karakoram terrane in the Early Jurassic. Younger Jurassic and Cretaceous ages record the development of an Andean-style volcanic arc along the southern Eurasian margin, which ended with the docking of the Kohistan island arc and the emplacement of the Kohistan-Ladakh batholith during the Late Cretaceous. The initial Eocene collision of India with Eurasia was followed by widespread hightemperature metamorphism and anatexis associated with crustal thickening within the Himalaya system in the Late Oligocene and Early Miocene.

Spatio-temporal variations of b-value in and around north Pakistan

“…Damaging earthquakes in and around north Pakistan are highlighted in yellow circle with the year of their occurrence (figure 2). According to Khan (2003), Khan et al (2010) Miocene (Faisal et al 2014). The collision between the Indian plate and the KIA resulted into the formation of the Himalayan mountain belts.…”

“…The youngest E-W trending Himalaya evolved in response to the collision of the Eurasian and Indian plates ∼50 million years ago (Faisal et al 2014). It stretches over 3000 km from Afghanistan in the west to Burma in the east and ranges in width from 250 to 350 km from south to north (Kearey and Vine 1990).…”

Microscale strain partitioning? Differential quartz crystallographic fabric development in Phyllite, Hindu Kush, Northwestern Pakistan

“…1). The geology of the area is dominated by Paleozoic protoliths, mainly low-grade metasedimentary rocks that locally reach sillimanite grade (Gaetani et al, 1996;Zanchi et al, 2000;Hildebrand et al, 2001;Zanchi and Gaetani, 2011;Faisal et al, 2014). These metasedimentary rocks are intruded by a series of plutonic bodies that range in age from Paleozoic (Kafiristan -483 ± 21 Ma; Debon et al, 1987), through Mesozoic (Tirich Mir -114 to 121 Ma, Desio, 1964;Hildebrand et al, 2000;Heuberger et al, 2007), to Cenozoic (Garam Chasma -24 Ma;Hildebrand et al, 1998).…”

“…These metasedimentary rocks are intruded by a series of plutonic bodies that range in age from Paleozoic (Kafiristan -483 ± 21 Ma; Debon et al, 1987), through Mesozoic (Tirich Mir -114 to 121 Ma, Desio, 1964;Hildebrand et al, 2000;Heuberger et al, 2007), to Cenozoic (Garam Chasma -24 Ma;Hildebrand et al, 1998). The region records a protracted deformational history with the earliest records indicating Late Triassic deformation and metamorphism and recent events culminating in the Early Miocene (Faisal et al, 2014).…”

“…Law et al, 2010) and to identify variable dissolution in quartz veins (Wilson et al, 2009). Such studies highlight the potentially significant differences in crystallographic fabric Faisal et al, 2014). Specimen collection location is indicated.…”