Rapid exhumation of the northern Jiaobei Terrane, North China Craton in the Early Cretaceous: Insights from Al-in-hornblende barometry and U-Pb geochronology

• Published in: Journal of Asian earth sciences Vol. 160; pp. 365 - 379
• Main Authors: Li, Xing-Hui, Fan, Hong-Rui, Zhang, Yong-Wen, Hu, Fang-Fang, Yang, Kui-Feng, Liu, Xuan, Cai, Ya-Chun, Zhao, Kui-Dong
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.07.2018
• Subjects: Fluid inclusion; Granodiorite; Hornblende thermobarometry; Monzogranite; Northern Jiaobei Terrane; Rapid exhumation; Northern Jiaobei Terrane; Monzogranite; Granodiorite; Hornblende thermobarometry; Fluid inclusion; Rapid exhumation
• ISSN: 1367-9120; 1878-5786
• DOI: 10.1016/j.jseaes.2017.10.001

•∼130 Ma Guojialing and ∼116 Ma Aishan plutons emplaced at ∼12 km and ∼5 km, respectively.•The Guojialing pluton had a rapid exhumation history during 130–116 Ma.•Most gold deposits in Jiaobei formed during or after the late stage of rapid exhumation of granodiorites.•The post-mineralization environment was relatively stable at least at ∼116 Ma. The Guojialing and Aishan plutons in the northern Jiaobei Terrane represent the magmatic products of the lithospheric thinning of the North China Craton in the Early Cretaceous. The exhumation history of the terrane in response to the thinning process and its effect on the formation and preservation of coeval gold deposits remain poorly constrained. Granodiorites from the Guojialing pluton and monzogranites from the Aishan pluton contain zircon grains with U-Pb ages of ca. 130 Ma and ca. 116 Ma, respectively. Using the Al-in-hornblende barometry, the Guojialing and Aishan plutons had crystallization pressures of 3.2–5.4 kbar (∼12 km) and 1.5–2.6 kbar (∼5 km), respectively. Using the hornblende-plagioclase thermometry, the Guojialing and Aishan plutons had crystallization temperatures of 628–697 °C and 702–745 °C, respectively. Fluid inclusion microthermometric data show that auriferous quartz veins in the Daliuhang deposit formed at temperatures between 243 and 322 °C at a depth of 7–11 km which was similar to the emplacement depth of the Aishan pluton. These thermobarometric and geochronological data reveal ∼7 km uplift between 130 Ma and 116 Ma, but negligible exhumation for the gold deposits after its formation until 116 Ma. Combining previous results, we envisage that the exhumation magnitude of the Guojialing intrusions were nearly the same in the wide area with slight differences between the core and margin of a single pluton. Numerous gold deposits in the Jiaobei Terrane formed during or after the late stage of rapid exhumation of granitoids, and were uplifted with similar depths to the Aishan pluton since ca. 116 Ma. The rapid exhumation of the Guojialing pluton was with the regional extension, and might be genetically associated with the intensive delamination of destabilized lithospheric root and dense residues.