TY - JOUR

T1 - The geodynamic significance of UHP exhumation

T2 - New constraints from Tso Morari Complex, NW Himalaya

AU - Bidgood, Anna

AU - Parsons, Andrew

AU - Roberts, Nick

AU - Waters, David

AU - Tapster, Simon

AU - Gopon, Phillip

PY - 2024/3/5

Y1 - 2024/3/5

N2 - The burial and exhumation of continental crust to and from ultrahigh-pressure (UHP) is an important orogenic process, ofteninterpreted with respect to the onset and/or subduction dynamics of continent-continent collision. Here, we investigate thetiming and significance of UHP metamorphism and exhumation of the Tso Morari complex, North-West Himalaya. We presentnew petrochronological analyses of mafic eclogites and their host-rock gneisses, combining U-Pb zircon, rutile and xenotimegeochronology (high-precision CA-ID-TIMS and high-spatial resolution LA-ICP-MS), garnet element maps, and petrographicobservations. Zircon from mafic eclogite have a CA-ID-TIMS age of 46.91 ± 0.07 Ma, with REE profiles indicative of growthat eclogite facies conditions. Those ages overlap with zircon rim ages (48.9 ± 1.2 Ma, LA-ICP-MS) and xenotime ages (47.4 ±1.4 Ma; LA-ICP-MS) from the hosting Puga gneiss, which grew during breakdown of UHP garnet rims. We argue that peakzircon growth at 47-46 Ma corresponds to the onset of exhumation from UHP conditions. Subsequent exhumation throughthe rutile closure temperature, is constrained by new dates of 40.4 ± 1.7 and 36.3 ± 3.8 Ma (LA-ICP-MS). Overlapping agesfrom Kaghan imply a coeval time-frame for the onset of UHP exhumation across the NW Himalaya. Furthermore, our regionalsynthesis demonstrates a causative link between changes in the subduction dynamics of the India-Asia collision zone at 47-46Ma and the resulting mid-Eocene plate network reorganization. The onset of UHP exhumation therefore provides a tightlyconstrained time-stamp significant geodynamic shifts within the orogen and wider plate network.

AB - The burial and exhumation of continental crust to and from ultrahigh-pressure (UHP) is an important orogenic process, ofteninterpreted with respect to the onset and/or subduction dynamics of continent-continent collision. Here, we investigate thetiming and significance of UHP metamorphism and exhumation of the Tso Morari complex, North-West Himalaya. We presentnew petrochronological analyses of mafic eclogites and their host-rock gneisses, combining U-Pb zircon, rutile and xenotimegeochronology (high-precision CA-ID-TIMS and high-spatial resolution LA-ICP-MS), garnet element maps, and petrographicobservations. Zircon from mafic eclogite have a CA-ID-TIMS age of 46.91 ± 0.07 Ma, with REE profiles indicative of growthat eclogite facies conditions. Those ages overlap with zircon rim ages (48.9 ± 1.2 Ma, LA-ICP-MS) and xenotime ages (47.4 ±1.4 Ma; LA-ICP-MS) from the hosting Puga gneiss, which grew during breakdown of UHP garnet rims. We argue that peakzircon growth at 47-46 Ma corresponds to the onset of exhumation from UHP conditions. Subsequent exhumation throughthe rutile closure temperature, is constrained by new dates of 40.4 ± 1.7 and 36.3 ± 3.8 Ma (LA-ICP-MS). Overlapping agesfrom Kaghan imply a coeval time-frame for the onset of UHP exhumation across the NW Himalaya. Furthermore, our regionalsynthesis demonstrates a causative link between changes in the subduction dynamics of the India-Asia collision zone at 47-46Ma and the resulting mid-Eocene plate network reorganization. The onset of UHP exhumation therefore provides a tightlyconstrained time-stamp significant geodynamic shifts within the orogen and wider plate network.

U2 - 10.22541/essoar.170965042.27714389/v1

DO - 10.22541/essoar.170965042.27714389/v1

M3 - Article

VL - ??? Stand: 10. Juli 2024

SP - ??? Stand: 10. Juli 2024

JO - Tectonics

JF - Tectonics

SN - 0278-7407

IS - ??? Stand: 10. Juli 2024

ER -