10.6084/m9.figshare.6509762.v1
Yun-hui Zhang
Yun-hui
Zhang
Hua-wen Cao
Hua-wen
Cao
Steven P. Hollis
Steven P.
Hollis
Li Tang
Li
Tang
Mo Xu
Mo
Xu
Jun-sheng Jiang
Jun-sheng
Jiang
Shun-bao Gao
Shun-bao
Gao
Yang-shuang Wang
Yang-shuang
Wang
Geochronology, geochemistry and Sr-Nd-Pb-Hf isotopes of the Early Paleogene gabbro and granite from Central Lhasa, southern Tibet: petrogenesis and tectonic implications
Taylor & Francis Group
2018
Petrogenesis
gabbro-granite
Early Paleogene
Neo-Tethyan Ocean
southern Tibet
2018-06-13 14:12:26
Dataset
https://tandf.figshare.com/articles/dataset/Geochronology_geochemistry_and_Sr-Nd-Pb-Hf_isotopes_of_the_Early_Paleogene_gabbro_and_granite_from_Central_Lhasa_southern_Tibet_petrogenesis_and_tectonic_implications/6509762
<p>The Tibetan Plateau is a composite orogenic belt that has experienced prolonged subduction, obduction, and collisional processes, during the opening and closure of successive Tethyan oceans. We present new zircon U-Pb ages and Hf isotopes, and whole-rock geochemical and Sr-Nd-Pb isotopic data from the Early Paleogene Longge’er gabbro and Qingduxiang granite of Central Lhasa, southern Tibet. Together these allow us to refine existing models for widespread magmatic activity associated with the subduction of the Neo-Tethyan Ocean. The Longge’er gabbro (53.5 ± 1.6 Ma) belongs to the low-K tholeiitic to medium-K and metaluminous series, while the Qingduxiang granite (54.5 ± 0.9 Ma) is characterized as high-K, calc-alkaline, metaluminous, and of I-type affinity. Both intrusions are enriched in the LREE and depleted in the HREE with negative Eu, Ba, Nb, Ta, Sr, and Ti anomalies. Trace elements characteristics and enriched whole-rock Sr-Nd-Pb and zircon Hf isotopic compositions demonstrate that the gabbro was derived from partial melting of enriched lithosphere mantle metasomatized by Central-Lhasa ancient crustal materials, while the I-type granite was generated by partial melting of Central-Lhasa ancient lower crust combined with magmas derived from Southern-Lhasa juvenile crust. Geochemical compositions of the gabbro and granite reveal the Early Paleogene magmatism was emplaced in a shallow extensional setting related to slab break off following the closure of the Neo-Tethyan Ocean. Combined with previous studies, we can infer slab rollback occurred from Late Cretaceous (~69 Ma) to Early Eocene (55 Ma), while slab break off was shortly lived at ca. 55–49 Ma. Consequently, the India-Asia collision must not have started later than ca. 55 Ma.</p>