TY - JOUR
T1 - The multi-stage tectonic evolution of the Xitieshan terrane, North Qaidam orogen, western China
T2 - From Grenville-age orogeny to early-Paleozoic ultrahigh-pressure metamorphism
AU - Zhang, Cong
AU - Bader, Thomas
AU - Zhang, Lifei
AU - van Roermund, Herman
PY - 2017/1
Y1 - 2017/1
N2 - The geodynamic evolution of the early Paleozoic ultrahigh-pressure metamorphic belt in North Qaidam, western China, is controversial due to ambiguous interpretations concerning the nature and ages of the eclogitic protoliths. Within this framework, we present new LA-ICP-MS U-Pb zircon ages from eclogites and their country rock gneisses from the Xitieshan terrane, located in the central part of the North Qaidam UHP metamorphic belt. Xitieshan terrane contains clearly different protolith characteristics of eclogites and as such provides a natural laboratory to investigate the geodynamic evolution of the North Qaidam UHP metamorphic terrane. LA-ICP-MS U-Pb zircon dating of three phengite-bearing eclogites and two country rock gneiss samples from the Xitieshan terrane yielded 424-427. Ma and 917-920. Ma ages, respectively. The age of 424-427. Ma from eclogite probably reflects continental lithosphere subduction post-dating oceanic lithosphere subduction at ~. 440-460. Ma. The 0.91-0.92. Ga metamorphic ages from gneiss and associated metamorphic mineral assemblages are interpreted as evidence for the occurrence of a Grenville-age orogeny in the North Qaidam UHPM belt. Using internal microstructure, geochemistry and U-Pb ages of zircon in this study, combined with the petrological and geochemical investigations on the eclogites of previous literature's data, three types of eclogitic protoliths are identified in the Xitieshan terrane i.e. 1) Subducted early Paleozoic oceanic crust (440-460. Ma), 2) Neoproterozoic oceanic crust material emplaced onto micro-continental fragments ahead of the main, early Paleozoic, collision event (440-420. Ma) and 3) Neoproterozoic mafic dikes intruded in continental fragments (rifted away from the former supercontinent Rodinia). These results demonstrate that the basement rocks of the North Qaidam terrane formed part of the former supercontinent Rodinia, attached to the Yangtze Craton and/or the Qinling microcontinent, and recorded a complex tectono-metamorphic evolution that involved Neoproterozoic and Early Paleozoic orogenies.
AB - The geodynamic evolution of the early Paleozoic ultrahigh-pressure metamorphic belt in North Qaidam, western China, is controversial due to ambiguous interpretations concerning the nature and ages of the eclogitic protoliths. Within this framework, we present new LA-ICP-MS U-Pb zircon ages from eclogites and their country rock gneisses from the Xitieshan terrane, located in the central part of the North Qaidam UHP metamorphic belt. Xitieshan terrane contains clearly different protolith characteristics of eclogites and as such provides a natural laboratory to investigate the geodynamic evolution of the North Qaidam UHP metamorphic terrane. LA-ICP-MS U-Pb zircon dating of three phengite-bearing eclogites and two country rock gneiss samples from the Xitieshan terrane yielded 424-427. Ma and 917-920. Ma ages, respectively. The age of 424-427. Ma from eclogite probably reflects continental lithosphere subduction post-dating oceanic lithosphere subduction at ~. 440-460. Ma. The 0.91-0.92. Ga metamorphic ages from gneiss and associated metamorphic mineral assemblages are interpreted as evidence for the occurrence of a Grenville-age orogeny in the North Qaidam UHPM belt. Using internal microstructure, geochemistry and U-Pb ages of zircon in this study, combined with the petrological and geochemical investigations on the eclogites of previous literature's data, three types of eclogitic protoliths are identified in the Xitieshan terrane i.e. 1) Subducted early Paleozoic oceanic crust (440-460. Ma), 2) Neoproterozoic oceanic crust material emplaced onto micro-continental fragments ahead of the main, early Paleozoic, collision event (440-420. Ma) and 3) Neoproterozoic mafic dikes intruded in continental fragments (rifted away from the former supercontinent Rodinia). These results demonstrate that the basement rocks of the North Qaidam terrane formed part of the former supercontinent Rodinia, attached to the Yangtze Craton and/or the Qinling microcontinent, and recorded a complex tectono-metamorphic evolution that involved Neoproterozoic and Early Paleozoic orogenies.
KW - Neoproterozoic orogeny
KW - North Qaidam UHP metamorphic belt
KW - Tectonic evolution
KW - U-Pb zircon geochronology
KW - Xitieshan
UR - http://www.scopus.com/inward/record.url?scp=84930919453&partnerID=8YFLogxK
U2 - 10.1016/j.gr.2015.04.011
DO - 10.1016/j.gr.2015.04.011
M3 - Article
AN - SCOPUS:84930919453
SN - 1342-937X
VL - 41
SP - 290
EP - 300
JO - Gondwana Research
JF - Gondwana Research
ER -