Eocene magmatic processes and crustal thickening in southern Tibet: Insights from strongly fractionated ca. 43Ma granites in the western Gangdese Batholith

Wang, Qing; Zhu, Di; Cawood, Peter A.; Zhi, Zhao; Liu, Sheng Ao; Chung, Sun‐Lin; Zhang, Liang Liang; Liu, Dong; Zheng, Yuan Chuan; Dai, Jin Gen

doi:10.1016/j.lithos.2015.10.003

Cited by 55 publications

(21 citation statements)

References 97 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…When slab‐derived and fractionated samples are excluded, these ratios are indicative of changing crustal thickness [e.g., Mantle and Collins , ; Chiaradia , ; Chapman et al ., ; Profeta et al ., ]. Such understanding, along with thickened lower crust‐derived geochemical signatures of the 50–10 Ma samples from the Gangdese Batholith [ Chung et al ., , ; Ji et al ., ; Guan et al ., ; Q. Wang et al ., ], enables us to extend the approach of Profeta et al . [], which is established from continental arc magmatism, to all filtered intermediate samples in quantifying the spatial and temporal variations in crustal thickness of the Gangdese arc.…”

Section: Methods and Resultsmentioning

confidence: 99%

Raising the Gangdese Mountains in southern Tibet

et al. 2017

Self Cite

View full text Add to dashboard Cite

The surface uplift of mountain belts is in large part controlled by the effects of crustal thickening and mantle dynamic processes (e.g., lithospheric delamination or slab breakoff). Understanding the history and driving mechanism of uplift of the southern Tibetan Plateau requires accurate knowledge on crustal thickening over time. Here we determine spatial and temporal variations in crustal thickness using whole‐rock La/Yb ratios of intermediate intrusive rocks from the Gangdese arc. Our results show that the crust was likely of normal thickness prior to approximately 70 Ma (~37 km) but began to thicken locally at approximately 70–60 Ma. The crust reached (58–50) ± 10 km at 55–45 Ma extending over 400 km along the strike of the arc. This thickening was likely due to magmatic underplating as a consequence of rollback and then breakoff of the subducting Neo‐Tethyan slab. The crust attained a thickness of 68 ± 12 km at approximately 20–10 Ma, as a consequence of underthrusting of India and associated thrust faulting. The Gangdese Mountains in southern Tibet broadly attained an elevation of >4000 m at approximately 55–45 Ma as a result of isostatic surface uplift driven by crustal thickening and slab breakoff and reached their present‐day elevation by 20–10 Ma. Our paleoelevation estimates are consistent not only with the C–O isotope‐based paleoaltimetry but also with the carbonate‐clumped isotope paleothermometer, exemplifying the promise of reconstructing paleoelevation in time and space for ancient orogens through a combination of magmatic composition and Airy isostatic compensation.

show abstract

Section: Methods and Resultsmentioning

confidence: 99%

Raising the Gangdese Mountains in southern Tibet

et al. 2017

Self Cite

View full text Add to dashboard Cite

show abstract

“…The Himalayan-Tibetan orogen is the world's highest and largest active orogen (Hou et al, 2012;Lu et al, 2019;Roberts & Searle, 2019; with the thickest continental crust (up to 60-80 km) on Earth, which is twice as thick as that of the normal crust (Ji, Wu, Liu, & Chung, 2012;Ma et al, 2014;Wang et al, 2015).…”

Section: Introductionmentioning

confidence: 99%

“…Although the presence of anomalously thick continental crust under this orogen has been known for a long time, the timing of crustal thickening is still under debate (Aikman, Harrison, & Lin, 2008;Chen et al, 2013;Chung et al, 2009;Ding & Lai, 2003;Guan et al, 2012;Lu et al, 2019;Wang et al, 2015;Zhang, Xia, Wang, Li, & Ye, 2004;Zhang, Zhang, Li, & Zhong, 2007;Zhang, Zhang, Tang, & Xia, 2012).…”

Section: Introductionmentioning

confidence: 99%

“…However, studies have mainly focused on the Lhasa or Qiangtang terrane, northern part of the Himalayan-Tibetan orogen (Chen et al, 2013;Chung et al, 2009;Guan et al, 2012;Ji et al, 2012;Lu et al, 2019;Ma et al, 2014;, FIGURE 1 Tectonic map of the Himalaya-Tibetan Plateau region: (a) geotectonic sketch of southeastern Asia Yin & Harrison, 2000); (b) simplified geological map of Himalaya, showing the distribution of leucogranites (modified after Cao et al, 2018;Guillot et al, 2008;. Age of Dajia granites is from Wang et al (2015); age of the Langshan gabbros is from Ji et al (2016); age of the Napuri adakitic rocks is from Ma et al (2014) [Colour figure can be viewed at wileyonlinelibrary.com] but few studies have focused on the southern part of this orogen due to a sparse adakitic magmatic record. Recently, some Eocene adakitic granites have been found within or near the Yardoi area, southern Tibet Hou et al, 2012;Xie et al, 2010;Zeng et al, 2014;Zeng, Gao, Xie, & Jing, 2011).…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Crustal thickening prior to 43 Ma in the Himalaya: Evidence from lower crust‐derived adakitic magmatism in Dala, eastern Tethyan Himalaya, Tibet

Dai

Dong

et al. 2019

Geological Journal

View full text Add to dashboard Cite

The Himalayan-Tibetan orogen is the world's largest active orogen with the thickest continental crust on Earth. However, the timing of crustal thickening of this orogen remains controversial. In recent years, magmatic rocks with adakitic affinities have been widely used to constrain the crustal thickness. Here, we present zircon U-Pb ages, geochemical and Sr-Nd-Pb-Hf isotopic data for the Dala two-mica granites (eastern Tethyan Himalaya) that may shed light on this issue. Zircon U-Pb dating shows that the Dala two-mica granites were emplaced at ca. 43 Ma. The granites display adakitic signatures, including high SiO 2 , Al 2 O 3 and Sr contents, low Y and Yb contents with high Sr/Y (27−67) and La/Yb (35−99) ratios. High K 2 O and Th contents, low Nb/U, Ce/Pb, Ti/Eu and Nd/Sm ratios and low MgO, Mg#, Cr and Ni contents suggest that the Dala two-mica granites were derived from partial melting of a thickened lower crust. Low negative zircon ε Hf (t) values (−10.4 to −0.5) with old two-stage Hf model ages (1.1-1.8 Ga), high ( 87 Sr/ 86 Sr) i (0.715861-0.717665) with low ε Nd (t) (−12.5 to −11.3) and high Pb isotopes [( 206 Pb/ 204 Pb) i =18.783-18.861, ( 207 Pb/ 204 Pb) i =18.783-18.861 and ( 208 Pb/ 204 Pb) i =39.052-39.285], together with previous literature data, indicate that the magma source for the Eocene granites in the Yardoi area was composed of ancient lower crust consisting mainly of garnetamphibolite and probably subordinate metapelites of the High Himalayan Crystalline Sequence. The residual mineral assemblage of garnet + rutile + plagioclase ± amphibole in the source region demonstrates that the crust beneath the Himalaya could have been thickened to 50 km in the Eocene. Combining with previous studies, we propose that the Eocene magmatic rocks in the Tethyan Himalaya (e.g. ca. 43 Ma old Dala two-mica granites) can be best interpreted as the consequence of breakoff of the Neo-Tethyan oceanic slab.

show abstract

“…The Lhasa terrane, with a length of over 2,000 km and a width of over 100 km, is a large crustal segment which is mainly composed of Precambrian crystalline basement and Palaeozoic to Mesozoic marine strata (Hou et al, ; Pan et al, , ; Wang et al, ; Zhu et al, , ; Zhu et al, , , ; Zhu, Zhao, Niu, Dilek, & Mo, ; Zhu, Zhao, Niu, Mo, et al, ). As a consequence of Neotethyan ocean subduction and continental collision between India and Eurasia, the Mesozoic to Cenozoic magmatic rocks are widely distributed in the Lhasa terrane (Cao et al, , ; Mo et al, ; Pan et al, , ; Zhu et al, ).…”

Section: Geological Setting and Sample Descriptionmentioning

confidence: 99%

Miocene potassic and adakitic intrusions in eastern central Lhasa terrane, Tibet: Implications for origin and tectonic of postcollisional magmatism

Zhi

Cao

et al. 2019

Geological Journal

View full text Add to dashboard Cite

Miocene postcollisional potassic and adakitic rocks are widely distributed in the southern Lhasa terrane and western central Lhasa terrane. However, coeval potassic and adakitic rocks in eastern central Lhasa terrane were rarely recognized, and their origins and formation mechanism remain controversial. In this paper, we provide new geochronological and geochemical data for the Miocene postcollisional potassic and adakitic intrusions exposed in the Qingdu area, eastern central Lhasa terrane, southern Tibet. The Qingdu Miocene intrusions consist of quartz monzonite porphyry and biotite granite with coeval zircon U–Pb ages of 14.1 Ma and 14.0 Ma, respectively. They have high SiO2 (67.98–75.32 wt.%), Al2O3 (14.13–14.78 wt.%), and K2O (4.06–6.18 wt.%) and low MgO (0.25–1.46 wt.%) contents. They are both enriched in light rare earth elements (LREEs) and depleted in heavy rare earth elements (HREEs), with high (La/Yb)N (25.37–42.32) ratios. The biotite granite samples have low Y (7.10–9.96 ppm) and Yb (0.61–0.85 ppm) contents, and high Sr (229–384 ppm) contents and high Sr/Y (30–41) ratios, which show adakitic geochemical characteristics, whereas the quartz monzonite porphyry samples show potassic geochemical characteristics. They display initial (87Sr/86Sr)i ratios of 0.7083–0.7103, εHf(t) values of −6.7 to −0.1, εNd(t) values of −8.96 to −7.44, (208Pb/204Pb)i ratios of 39.028–39.110, (207Pb/204Pb)i ratios of 15.662–15.684, and (206Pb/204Pb)i ratios of 18.541–18.577. These signatures indicate that both the potassic and adakitic intrusions are more likely to originate from partial melting of a thickened lower crust, which were mainly the products of the binary mixing between the juvenile and ancient crust components. Based on the spatial distributions and isotopic features of the postcollisional potassic and adakitic rocks in the Lhasa terrane, we suggest that the differences of the lower crustal composition played a crucial role in causing the geochemical variations of the Miocene postcollisional adakitic and potassic rocks in Lhasa terrane.

show abstract

Eocene magmatic processes and crustal thickening in southern Tibet: Insights from strongly fractionated ca. 43Ma granites in the western Gangdese Batholith

Cited by 55 publications

References 97 publications

Raising the Gangdese Mountains in southern Tibet

Raising the Gangdese Mountains in southern Tibet

Crustal thickening prior to 43 Ma in the Himalaya: Evidence from lower crust‐derived adakitic magmatism in Dala, eastern Tethyan Himalaya, Tibet

Miocene potassic and adakitic intrusions in eastern central Lhasa terrane, Tibet: Implications for origin and tectonic of postcollisional magmatism

Contact Info

Product

Resources

About