The Dulan ultrahigh-pressure (UHP) rocks of the North Qaidam terrane, Western China, represent continental crust that has been subducted ~100 km during continental collision. Adjacent granulites representing burial to ~50 km could either be overprinted eclogites or a separate high-pressure-high-temperature (HP-HT) granulite unit. Overprinted eclogites and HP-HT granulites imply different P-T-t paths for UHP rocks. Metamorphic conditions for the granulites are 750–880 °C and 14–17 kbar. Zircon U-Pb geochronology, REE patterns and Ti-in-zircon thermometry indicate an increase in temperature from ~800 °C (449 Ma) to ~900 °C (418 Ma). This temperature increase could explain the presence of granulite leucosomes and tonalites (419 Ma) interpreted to represent partial melts. The temperature increase coincides with the end of UHP metamorphism and may be related to exhumation of UHP rocks. These granulites represent a separate HP-HT unit from the thickened overriding crust in a continental collision zone, above subducting UHP rocks.
","abstract_html":"<p>The Dulan ultrahigh-pressure (UHP) rocks of the North Qaidam terrane, Western China, represent continental crust that has been subducted ~100 km during continental collision. Adjacent granulites representing burial to ~50 km could either be overprinted eclogites or a separate high-pressure-high-temperature (HP-HT) granulite unit. Overprinted eclogites and HP-HT granulites imply different P-T-t paths for UHP rocks. Metamorphic conditions for the granulites are 750–880 °C and 14–17 kbar. Zircon U-Pb geochronology, REE patterns and Ti-in-zircon thermometry indicate an increase in temperature from ~800 °C (449 Ma) to ~900 °C (418 Ma). This temperature increase could explain the presence of granulite leucosomes and tonalites (419 Ma) interpreted to represent partial melts. The temperature increase coincides with the end of UHP metamorphism and may be related to exhumation of UHP rocks. These granulites represent a separate HP-HT unit from the thickened overriding crust in a continental collision zone, above subducting UHP rocks.</p>","abstract_has_math":false,"creators":["Christensen, Benjamin David Joseph"],"institution":null,"degree_name":"Master of Science (MS)","degree_level":null,"degree_discipline":"Geological Sciences","degree_department":null,"school":null,"contributors":["Chris Mattinson","Audrey Huerta","Jeff Lee"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2011,"date_issued":"2011-01-01T08:00:00Z","date_published":"2011-01-01T08:00:00Z","updated_at":"2026-07-24T01:37:54Z","subjects":["China","Dulan","Geology","geochronology","Geochemistry","Stratigraphy","Tectonics and Structure"],"languages":[],"rights":[],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"https://digitalcommons.cwu.edu/etd/1455","outbound_label":"Repository record","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Chris Mattinson","Audrey Huerta","Jeff Lee"]},{"key":"dc:creator","label":"Author","values":["Christensen, Benjamin David Joseph"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.available","label":"Dc Date Available","values":["2020-12-18T08:00:00Z"]},{"key":"dc:type","label":"Dc Type","values":["Text"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Geological Sciences"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Master of Science (MS)"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["China","Dulan","Geology","geochronology","Geochemistry","Stratigraphy","Tectonics and Structure"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["https://digitalcommons.cwu.edu/etd/1455"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["The Dulan ultrahigh-pressure (UHP) rocks of the North Qaidam terrane, Western China, represent continental crust that has been subducted ~100 km during continental collision. Adjacent granulites representing burial to ~50 km could either be overprinted eclogites or a separate high-pressure-high-temperature (HP-HT) granulite unit. Overprinted eclogites and HP-HT granulites imply different P-T-t paths for UHP rocks. Metamorphic conditions for the granulites are 750–880 °C and 14–17 kbar. Zircon U-Pb geochronology, REE patterns and Ti-in-zircon thermometry indicate an increase in temperature from ~800 °C (449 Ma) to ~900 °C (418 Ma). This temperature increase could explain the presence of granulite leucosomes and tonalites (419 Ma) interpreted to represent partial melts. The temperature increase coincides with the end of UHP metamorphism and may be related to exhumation of UHP rocks. These granulites represent a separate HP-HT unit from the thickened overriding crust in a continental collision zone, above subducting UHP rocks.
"]},{"key":"dc:title","label":"Title","values":["Geochemistry, Geothermobarometry and Geochronology of High-Pressure Granulites and Implications for the Exhumation History of Ultrahigh-Pressure Terranes: Dulan, Western China"]}]}],"canonical_facts":{"dc:contributor":["Chris Mattinson","Audrey Huerta","Jeff Lee"],"dc:creator":["Christensen, Benjamin David Joseph"],"dc:date.available":["2020-12-18T08:00:00Z"],"dc:description.abstract":["The Dulan ultrahigh-pressure (UHP) rocks of the North Qaidam terrane, Western China, represent continental crust that has been subducted ~100 km during continental collision. Adjacent granulites representing burial to ~50 km could either be overprinted eclogites or a separate high-pressure-high-temperature (HP-HT) granulite unit. Overprinted eclogites and HP-HT granulites imply different P-T-t paths for UHP rocks. Metamorphic conditions for the granulites are 750–880 °C and 14–17 kbar. Zircon U-Pb geochronology, REE patterns and Ti-in-zircon thermometry indicate an increase in temperature from ~800 °C (449 Ma) to ~900 °C (418 Ma). This temperature increase could explain the presence of granulite leucosomes and tonalites (419 Ma) interpreted to represent partial melts. The temperature increase coincides with the end of UHP metamorphism and may be related to exhumation of UHP rocks. These granulites represent a separate HP-HT unit from the thickened overriding crust in a continental collision zone, above subducting UHP rocks.
"],"dc:identifier":["https://digitalcommons.cwu.edu/etd/1455"],"dc:subject":["China","Dulan","Geology","geochronology","Geochemistry","Stratigraphy","Tectonics and Structure"],"dc:title":["Geochemistry, Geothermobarometry and Geochronology of High-Pressure Granulites and Implications for the Exhumation History of Ultrahigh-Pressure Terranes: Dulan, Western China"],"dc:type":["Text"],"thesis:degree_discipline":["Geological Sciences"],"thesis:degree_name":["Master of Science (MS)"]},"updated_at":"2026-07-24T01:37:54Z"}