TY - JOUR
T1 - The Geodynamic Significance of Continental UHP Exhumation
T2 - New Constraints From the Tso Morari Complex, NW Himalaya
AU - Bidgood, Anna
AU - Parsons, Andrew
AU - Roberts, Nick
AU - Waters, David
AU - Tapster, Simon
AU - Gopon, Phillip
PY - 2024/4/26
Y1 - 2024/4/26
N2 - The burial and exhumation of continental crust to and from ultrahigh-pressure (UHP) is an important orogenic process, often interpreted with respect to the onset and/or subduction dynamics of continent-continent collision. Here, we investigate the timing and significance of UHP metamorphism and exhumation of the Tso Morari complex, North-West Himalaya. We present new petrochronological analyses of mafic eclogites and their host-rock gneisses, combining U-Pb zircon, rutile and xenotime geochronology (high-precision CA-ID-TIMS and high-spatial resolution LA-ICP-MS), garnet element maps, and petrographic observations. Zircon from mafic eclogite have a CA-ID-TIMS age of 46.91 ± 0.07 Ma, with REE profiles indicative of growth at 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 peak zircon growth at 47–46 Ma corresponds to the onset of exhumation from UHP conditions. Subsequent exhumation through the rutile closure temperature, is constrained by new dates of 40.4 ± 1.7 and 36.3 ± 3.8 Ma (LA-ICP-MS). Overlapping ages from Kaghan imply a coeval time-frame for the onset of UHP exhumation across the NW Himalaya. Furthermore, our regional synthesis demonstrates a causative link between changes in the subduction dynamics of the India-Asia collision zone at 47–46 Ma and the resulting mid-Eocene plate network reorganization. The onset of UHP exhumation therefore provides a tightly constrained 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, often interpreted with respect to the onset and/or subduction dynamics of continent-continent collision. Here, we investigate the timing and significance of UHP metamorphism and exhumation of the Tso Morari complex, North-West Himalaya. We present new petrochronological analyses of mafic eclogites and their host-rock gneisses, combining U-Pb zircon, rutile and xenotime geochronology (high-precision CA-ID-TIMS and high-spatial resolution LA-ICP-MS), garnet element maps, and petrographic observations. Zircon from mafic eclogite have a CA-ID-TIMS age of 46.91 ± 0.07 Ma, with REE profiles indicative of growth at 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 peak zircon growth at 47–46 Ma corresponds to the onset of exhumation from UHP conditions. Subsequent exhumation through the rutile closure temperature, is constrained by new dates of 40.4 ± 1.7 and 36.3 ± 3.8 Ma (LA-ICP-MS). Overlapping ages from Kaghan imply a coeval time-frame for the onset of UHP exhumation across the NW Himalaya. Furthermore, our regional synthesis demonstrates a causative link between changes in the subduction dynamics of the India-Asia collision zone at 47–46 Ma and the resulting mid-Eocene plate network reorganization. The onset of UHP exhumation therefore provides a tightly constrained time-stamp significant geodynamic shifts within the orogen and wider plate network.
UR - https://pureadmin.unileoben.ac.at/portal/en/publications/the-geodynamic-significance-of-uhp-exhumation(b130d428-5650-4805-8235-79bc0de6bb8e).html
U2 - 10.1029/2023TC007976
DO - 10.1029/2023TC007976
M3 - Article
SN - 0278-7407
VL - 43.2024
JO - Tectonics
JF - Tectonics
IS - 5
M1 - e2023TC007976
ER -