Origin of Miocene Cu-bearing porphyries in the Zhunuo region of the southern Lhasa subterrane: Constraints from geochronology and geochemistry

Zeng, Yunbo; Chen, Jianlin; Xu, Ji‐Feng; Lei, Ming; Xiong, Qiu-Wei

doi:10.1016/j.gr.2015.06.011

Cited by 42 publications

(40 citation statements)

References 101 publications

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“…Zircon UPb age and Hf isotopic data for potassic volcanic rocks (Liu et al, 2014b;Hou et al, 2015a;Tian et al, 2015;Zhang et al, 2015), the Eocene-Miocene adakitic intrusions (Chung et al, 2009;Xu et al, 2010;Li et al, 2011;Guan et al, 2012;Ji et al, 2012;Zheng et al, 2012;Ma et al, 2014;Hou et al, 2015a;Wang et al, 2015), mantle-derived ultrapotassic rocks (Sun et al, 2008;Liu et al, 2014a;Tian et al, 2015), and the high Himalayan gneiss (Chu et al, 2011) , 2002). Previously reported Eocene-Miocene adakitic rocks (Zhao et al, 2001;Hou et al, 2004Hou et al, , 2015aChung et al, 2005;Guo et al, 2007b;Xu et al, 2010;Li et al, 2011;Guan et al, 2012;Ji et al, 2012;Ma et al, 2014;Wang et al, 2015;Yang et al, 2015;Zeng et al, 2016) and potassic volcanic rocks (Turner et al, 1996;Miller et al, 1999;Zhao et al, 2001;Williams et al, 2004;Gao et al, 2007Gao et al, , 2009Wang et al, 2008;Chen et al, 2010Chen et al, , 2011Chen et al, , ...…”

Section: Discussionmentioning

confidence: 97%

Potassic volcanic rocks and adakitic intrusions in southern Tibet: Insights into mantle–crust interaction and mass transfer from Indian plate

Liu

Zhao

DePaolo

et al. 2017

Lithos

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Elucidating geodynamic processes at depth relies on a correct interpretation of petrological and geochemical features in magmatic records. In southern Tibet, both potassic volcanic rocks and adakitic intrusions exhibit high Sr/Y and La/Yb, and low Y and Yb concentrations. But these two rocks types have contrasting temporal-spatial distributions and isotopic variations. Here we present a systematic study on the postcollisional potassic and adakitic rocks in order to investigate their petrogenetic links with the coeval mantle-derived ultrapotassic rocks and shed light on the potential input from underthrusted Indian continental crust. We found that adakitic intrusions with higher K 2 O/Na 2 O tend to display lower Y and higher SiO 2 , suggesting that the mantle-derived ultrapotassic melts, showing relatively high Y and Yb concentrations, only played a minor role in adakitic magmatism. Therefore, unradiogenic 143 Nd/ 144 Nd and the dramatic decrease of zircon ε Hf (t) values since ~35 Ma shown by postcollisional adakites should be interpreted as reflecting the crust input from Indian continental crust. Unlike adakitic intrusions in southern Lhasa subterrane, potassic volcanic rocks share similar spatial distributions with ultrapotassic rocks, and their isotopic discrepancy is diminishing with volcanic activity becomes younger and migrates eastward. Evidence from whole-rock Pb and zircon Hf isotopes further indicates that potassic volcanic rocks are more likely to originate from partial melting of the overthickened and isotopically heterogeneous Lhasa terrane crust rather than the underthrusted Indian crust. The elevated Rb/Sr and varying Sr/CaO in potassic volcanic rocks provide an argument for sanidine + plagioclase + clinopyroxene as the major fractionating phases during magmatic differentiation. These findings not only highlight the significance of potassic and adakitic rocks in providing constraints on the geodynamic processes beneath southern Tibet, but also imply that special caution is needed if we attempt to probe into the nature of mantle lithosphere using isotopic tracers from the Tibetan ultrapotassic rocks.

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Section: Discussionmentioning

confidence: 97%

Potassic volcanic rocks and adakitic intrusions in southern Tibet: Insights into mantle–crust interaction and mass transfer from Indian plate

Liu

Zhao

DePaolo

et al. 2017

Lithos

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“…The sedimentary cover in the southern Lhasa Subterrane is limited, and is mainly of Late Triassic‐Cretaceous age (Zhu et al, ). After the collision between India and Asia, two types of postcollisional magmatic rocks were emplaced in the southern Lhasa Subterrane between 25 and 10 Ma: adakitic intrusive rocks and potassic‐ultrapotassic volcanic rocks (Chung et al, ; Hou et al, ; Huang et al, ; Wang et al, 2014; Zeng et al, ). The ultrapotassic volcanic rocks were derived from low‐degree partial melting of metasomatized lithospheric mantle (Huang et al, ; Zhao et al, ; Wang et al, 2014).…”

Section: Geological Backgroundmentioning

confidence: 99%

Slab Breakoff of the Neo‐Tethys Ocean in the Lhasa Terrane Inferred From Contemporaneous Melting of the Mantle and Crust

Huang

Zeng

et al. 2017

Geochem Geophys Geosyst

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Oceanic slab breakoff significantly affects the thermal regime of the lithosphere during continental collision. This often triggers extension‐related mafic magmatism and crustal melting. It is generally accepted that the Neo‐Tethyan lithosphere subducted beneath the southern Lhasa Subterrane, resulting in the formation of the Gangdese magmatic arc. However, the timing of slab breakoff is still disputed, due to a lack of evidence for extension‐related mafic magmatism. In this study, we provide comprehensive age, element and Sr–Nd–Hf isotopic data of mafic dikes, felsic intrusions, and enclaves from the Daju area, southern Lhasa Subterrane. The timing of mafic dikes and granitoids are contemporaneous at circa 57 Ma. The mafic dikes are characterized by high Th/U, and Zr/Y ratios, their geochemistry indicates an intraplate affinity rather than arc magmas. Furthermore, the mafic dikes show strongly variable igneous zircon ɛHf(t), and lower whole‐rock ɛNd(t) than granitoids. This evidence suggests that the mafic dikes represent asthenosphere‐derived melts contaminated by various degrees of ancient lithosphere. However, the granitoids were directly derived from the juvenile lower crust. Given the abrupt decrease in the convergence rate between India and Asia, and the surface uplift and sedimentation cessation in the southern Lhasa Subterrane in the early Cenozoic, the occurrence of synchronous mafic dikes and granitoids is best explained by a slab breakoff model. The occurrence of intraplate‐type magmas likely corresponds to the magmatic expression of the initial stage of Neo‐Tethyan slab breakoff. The slab breakoff concept also explains the onset of the magmatic “flare‐up” and crustal growth after 57 Ma.

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“…After the collision between India and Asia, three types of postcollisional magmatites were widely emplaced in the Lhasa Terrane: adakitic intrusive rocks, potassic-ultrapotassic volcanic rocks, and peraluminous granites were emplaced between 25 and 10 Ma (Chung et al, 2005Hou et al, 2004;Huang et al, 2015b;Liao et al, 2007;Mo et al, 2007;Zeng et al, 2015). The ultrapotassic volcanic rocks were derived from low-degree partial melting of metasomatized lithospheric mantle and are only found west of 87°E (Chung et al, 2005;Huang et al, 2015b;Williams et al, 2001;Zhao et al, 2009).…”

Section: Geological Backgroundmentioning

confidence: 99%

Two Cenozoic tectonic events of N–S and E–W extension in the Lhasa Terrane: Evidence from geology and geochronology

Huang

Chen

et al. 2016

Lithos

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Origin of Miocene Cu-bearing porphyries in the Zhunuo region of the southern Lhasa subterrane: Constraints from geochronology and geochemistry

Cited by 42 publications

References 101 publications

Potassic volcanic rocks and adakitic intrusions in southern Tibet: Insights into mantle–crust interaction and mass transfer from Indian plate

Potassic volcanic rocks and adakitic intrusions in southern Tibet: Insights into mantle–crust interaction and mass transfer from Indian plate

Slab Breakoff of the Neo‐Tethys Ocean in the Lhasa Terrane Inferred From Contemporaneous Melting of the Mantle and Crust

Two Cenozoic tectonic events of N–S and E–W extension in the Lhasa Terrane: Evidence from geology and geochronology

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