DOI: 10.1007/s00531-012-0849-1
Scopus记录号: 2-s2.0-84878112488
论文题名: Geochronology and geochemistry of the Early Cretaceous Jigongshan and Qijianfeng batholiths in the Tongbai orogen, central China: Implications for lower crustal delamination
作者: Zhang J. ; Ma C. ; Li J. ; She Z. ; Zhang C.
刊名: International Journal of Earth Sciences
ISSN: 14373254
出版年: 2013
卷: 102, 期: 4 起始页码: 1045
结束页码: 1067
语种: 英语
英文关键词: Adakite
; Central China
; Delamination
; Granite
; Tongbai orogen
Scopus关键词: adakite
; batholith
; biotite
; Cretaceous
; delamination
; dike
; diorite
; emplacement
; geochemistry
; geochronology
; granite
; hornblende
; lower crust
; orogeny
; partial melting
; uranium-lead dating
; China
; Henan
; Tongbai
英文摘要: The Jigongshan and Qijianfeng batholiths in the Tongbai orogen consist mainly of porphyritic hornblende-biotite monzogranite, biotite monzogranite, and biotite syenogranite, which are variably intruded by lamprophyre, diorite, and syenogranite dykes. Mafic microgranular enclaves commonly occur in the hornblende-biotite monzogranite, whereas surmicaceous enclaves are found in the biotite monzogranite. Both batholiths have zircon U-Pb ages ranging from ca. 139 to 120 Ma, indicating their emplacement in the Early Cretaceous. The hornblende-biotite monzogranite has an adakitic affinity marked by relatively high Sr/Y and (La/Yb)N ratios, lack of Eu anomalies, low MgO and Ni contents, and Na2O > K2O. Its chemical compositions, combined with enriched Sr-Nd isotopic signatures, suggest formation by dehydration melting of mafic rocks in a thickened lower crust. This thickened crust resulted from the Permo-Triassic subduction-collision between the North China and South China blocks and persisted until the Early Cretaceous. The biotite monzogranite and biotite syenogranite have low Al2O3, CaO, and Sr contents, low Rb/Sr, FeOt/MgO, and (Na2O + K2O)/CaO ratios, and flat HREE patterns with moderate to weak Eu anomalies. They were produced by partial melting of crustal materials under relatively low pressure. Partial melting at different crustal levels could have significantly contributed to mechanical weakening of the crust. The diorite and lamprophyre dykes show linear trends between SiO2 and major or trace elements on Harker diagrams, with two lamprophyre samples containing normative nepheline and olivine. These rocks have high La/Yb and Dy/Yb ratios, both displaying co-variation with contents of Yb. They were originated from relatively deep lithospheric mantle followed by fractionation of olivine + clinopyroxene + apatite + Fe-Ti oxides. Extensive partial melting in the lithospheric mantle indicates relatively high temperatures at this level. We suggest that the presence of adakitic magmas, thickened but weakened crust and high temperatures in the lithosphere mantle point to lower crustal delamination in the Early Cretaceous in the Tongbai orogen. © 2012 Springer-Verlag Berlin Heidelberg. URL: https://www.scopus.com/inward/record.uri?eid=2-s2.0-84878112488&doi=10.1007%2fs00531-012-0849-1&partnerID=40&md5=f88c78ed70cb3f992d5b0fa00db37471
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资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/70555
Appears in Collections: 影响、适应和脆弱性 气候减缓与适应
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作者单位: Faculty of Earth Resources, China University of Geosciences, Wuhan, 430074, China; Faculty of Earth Sciences, China University of Geosciences, Wuhan, 430074, China; State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Wuhan, 430074, China
Recommended Citation:
Zhang J.,Ma C.,Li J.,et al. Geochronology and geochemistry of the Early Cretaceous Jigongshan and Qijianfeng batholiths in the Tongbai orogen, central China: Implications for lower crustal delamination[J]. International Journal of Earth Sciences,2013-01-01,102(4)