Origin of adakitic intrusives generated during mid-Miocene east–west extension in southern Tibet

Hou, Zhenshan; Gao, Yan; Qu, Xiaoming; Zhang, Rui; Mo, Xuanxue

doi:10.1016/s0012-821x(04)00007-x

Cited by 830 publications

(503 citation statements)

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“…2). These results are consistent with the age data reported by Chung et al (2003) and Hou et al (2004).…”

Section: La-icp-ms Zircon U-pb Data (Appendix 3) Shown Insupporting

confidence: 93%

“…The localities are as follows (from east to west): 1, Linzhi (Chung et al, 2003); 2, Jiama (Hou et al, 2004, the present study); 3, Qulong (Hou et al, 2004); 4, Lakang'e (Hou et al, 2004, the present study); 5, Nanmu (Hou et al, 2004); 6, Nemu (Hou et al, 2004, the present study); 7, Maquiang (Turner et al, 1996); 8, Xigaze (Chung et al, 2003); 9, Daggyaio Tso (Williams et al, 2004); 10, Manasarowar and Gegar (Miller et al, 1999); 11, Bangba (the present study); 12, Shiduo (Cai et al, 2005); 13, Shiquanhe (Guo et al, 2007); and 14, Ritu (Cai et al, 2005). The adakitic rocks in the Tethyan Himalayan tectonic zone are as follows: 15 Mayum and 16 Kuday (King et al, 2007).…”

Section: Analytical Techniquesmentioning

confidence: 99%

“…Miocene adakitic rocks in Southern Tibet are thought to have originated from a thickened lower crust (Cai et al, 2005;Chung et al, 2003Chung et al, , 2009Gao et al, 2007a;Guo et al, 2007;Hou et al, 2004;Jiang et al, 2006), meaning that their compositions reflect the geochemical characteristics of their lower crustal source(s). Here, we present new geochemical data and Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS) U-Pb zircon age data for adakitic rocks in the Lhasa terrane, which, when combined with previous geochemical data, allows us to assess possible sources on both sides of the IYS.…”

Section: Introductionmentioning

confidence: 99%

“…Previous studies have shown that the adakitic rocks are K-rich, forming a 1000-km-long belt oriented sub-parallel to the IYS. The ages of the adakitic rocks range from 26.2 to 10 Ma (Cai et al, 2005;Chung et al, 2003Chung et al, , 2009Gao et al, 2007a;Guo et al, 2007;Hou et al, 2004;Xu et al, 2010;this study), within the range of the 22.5-12 Ma ages obtained for potassic-ultrapotassic igneous rocks in the Lhasa terrane (e.g., Ding et al, 2003;Gao et al, 2007b;Miller et al, 1999;Nomade et al, 2004;Williams et al, 2001Williams et al, , 2004Zhao et al, 2009), except for the 26.2 Ma age of adakitic rocks in Linzhi (Chung et al, 2003). Recently, Miocene adakitic dykes have been found on the southern side of the IYS, including the Mayum and Kuday dykes King et al, 2007) within the northern belt of the Tethyan Himalayan tectonic zone.…”

Section: Introductionmentioning

confidence: 99%

“…The groundmasses of these porphyries consist mainly of plagioclase, alkali feldspar, biotite, quartz, zircon, Fe-Ti oxides, titanite, apatite, and glass. The petrographic characteristics of these adakitic rocks have been described by Hou et al (2004), Guo et al (2007), and Gao et al (2007aGao et al ( , 2007b. In the western Lhasa terrane, the adakitic rocks occur as erupted lavas or small intrusive bodies.…”

Section: Introductionmentioning

confidence: 99%

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Geochemical variations in Miocene adakitic rocks from the western and eastern Lhasa terrane: Implications for lower crustal flow beneath the Southern Tibetan Plateau

Chen

Zhao

et al. 2011

Lithos

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“…2). These results are consistent with the age data reported by Chung et al (2003) and Hou et al (2004).…”

Section: La-icp-ms Zircon U-pb Data (Appendix 3) Shown Insupporting

confidence: 93%

Section: Analytical Techniquesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Geochemical variations in Miocene adakitic rocks from the western and eastern Lhasa terrane: Implications for lower crustal flow beneath the Southern Tibetan Plateau

Chen

Zhao

et al. 2011

Lithos

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Eocene adakitic porphyries in the central‐northern Qiangtang Block, central Tibet: Partial melting of thickened lower crust and implications for initial surface uplifting of the plateau

Wang

Wyman

et al. 2017

JGR Solid Earth

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The time and mechanism of crustal thickening and initial surface uplift of the Tibetan Plateau remain highly controversial. Here we report on zircon U‐Pb age, and mineral, element, and Sr‐Nd isotope composition data for Eocene adakitic porphyries in the Laorite Co area of central‐northern Qiangtang Block, central Tibet. Laser ablation‐inductively coupled plasma‐mass spectrometry zircon U‐Pb age dating shows that the porphyries were generated at 42–41 Ma. All samples display adakitic geochemical characteristics, such as high SiO2 and Al2O3, and low Y and Yb contents, and high Sr/Y and La/Yb ratios with positive Sr and negligible Eu anomalies and Nb‐Ta depletion. They also have low magnesium number (Mg #) (16–45) and high K2O (4.0–4.6 wt %) values, as well as high (87Sr/86Sr)i (0.7076–0.7080) and low εNd(t) (−5.9 to −4.4) values. These adakitic rocks were most probably generated by partial melting of thickened lower crust in the stability field of garnet, amphibole, and rutile but with relatively minor plagioclase. Moreover, such a crustal thickening process beneath this block likely occurred no later than the middle Eocene and was most probably caused by the southward subduction of the Songpan‐Ganzi Block in the early Cenozoic. In addition, the occurrences of exposed adakitic porphyries unambiguously indicate that exhumation process occurred after their formation. Thus, these ~42 Ma adakitic porphyries indicate the occurrence of significant exhumation since 42 Ma. Integrated with the thermochronological and paleoelevation data, we suggest that the initial surface uplift of the Qiangtang Block, triggered by crustal thickening, was underway by the middle Eocene (~42 Ma).

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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.

show abstract

Origin of adakitic intrusives generated during mid-Miocene east–west extension in southern Tibet

Cited by 830 publications

References 50 publications

Geochemical variations in Miocene adakitic rocks from the western and eastern Lhasa terrane: Implications for lower crustal flow beneath the Southern Tibetan Plateau

Geochemical variations in Miocene adakitic rocks from the western and eastern Lhasa terrane: Implications for lower crustal flow beneath the Southern Tibetan Plateau

Eocene adakitic porphyries in the central‐northern Qiangtang Block, central Tibet: Partial melting of thickened lower crust and implications for initial surface uplifting of the plateau

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

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