Origin and tectonic implications of the Shiquanhe high-Mg andesite, western Bangong suture, Tibet

Liu, Weiliang; Huang, Qiangtai; Gu, Man; Zhong, Yun; Zhou, Renjie; Gu, Xiaodong; Zheng, Hangping; Liu, Jingnan; Lu, Xingxin; Xia, Bin

doi:10.1016/j.gr.2018.03.017

Cited by 50 publications

(21 citation statements)

References 82 publications

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“…The subduction of the BNO beneath the Qiangtang block gave birth to the Jurassic-Cretaceous continental arc along the southern margin of the Qiangtang block ( Figure 2b) [13,15,28,29], and caused ophiolite obduction near Dongqiao during the Middle Jurassic [30]. Synchronous to the oceanic-continental subduction, oceanic subduction within the BNO also commenced no later than the Middle Jurassic, and consequently a Jurassic oceanic arc was formed south of the Qiangtang continental arc (Figure 2b) [19,20,31,32]. As these subductions continued, the ocean basin narrowed rapidly.…”

Section: Tectonic Evolution Of the Bangong-nujiang Oceanmentioning

confidence: 99%

“…Previous recognition of BNS oceanic arc rocks has been mainly based on geochemical evidence from the volcanic rocks that are associated with ophiolitic fragments (SSZ type ophiolite), and suggests that an oceanic subduction occurred within the BNO [10,31,[83][84][85]. Importantly, the discoveries of boninitic rocks near Dingqing [17], Daruco [20], Shiquanhe [19], and Rutog [18] in the BNS provide further evidence of the existence of an oceanic arc within the BNO. However, the extremely localized outcrops of these volcanic rocks make it hard to trace them in the field, and thus hamper further studies on the development and configuration of this arc.…”

Section: Oceanic Arc Development and Two Contrasting Sources For Magmmentioning

confidence: 99%

“…Studies on the high-Mg andesites from Shiquanhe ( Figure 3) and Daruco (Figure 1) show arc-type geochemical compositions and enriched Nd (ε Nd (t) = −8.7 to −13.4) and Hf (ε Hf (t) = −7.4 to −16.2) isotopes. It has been proposed that these high-Mg andesites are formed by the melting of subducted sediments ( Figure 12) and subsequent interaction with overlying mantle peridotites during subduction initiation [19,20]. In contrast with the enriched isotopes of the above high-Mg andesites, zircon Lu-Hf isotopes of the Lameila pluton were depleted, with ε Hf (t) ranging from 10.5 to 13.9.…”

Section: Oceanic Arc Development and Two Contrasting Sources For Magmmentioning

confidence: 99%

“…According to Shi et al [18], the boninitic andesites in the BNS near Rutog record the fore arc volcanism associated with oceanic subduction. Recent studies on the 164-161 Ma high-Mg andesites from Shiquanhe [19] and Daruco [20] have suggested a Jurassic oceanic arc developed within the BNO. Apart from these significant findings, the configuration of this arc, such as its crustal thickness and the source(s) for the arc magmatism are still unclear.…”

Section: Introductionmentioning

confidence: 99%

“…Plot of ε Hf (t) versus age for the Lameila pluton. Data for the Jurassic Qiangtang arc are from Liu et al[15]; data for the BNO high-Mg andesite are from Liu et al[19] and Zeng et al[20].…”

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confidence: 99%

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Dating Oceanic Subduction in the Jurassic Bangong–Nujiang Oceanic Arc: A Zircon U–Pb Age and Lu–Hf Isotopes and Al-in-Hornblende Barometry Study of the Lameila Pluton in Western Tibet, China

2019

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The subduction and close of the Mesozoic Bangong–Nujiang Ocean (BNO) led to a collision of the Lhasa and Qiangtang blocks, which formed the backbone of the Tibetan Plateau (the largest and highest plateau on Earth). However, the detailed subduction processes (in particular, the oceanic subduction processes) within the BNO are still not clear. Here, we focus on the plutonic complex of the oceanic arc in the Bangong–Nujiang suture (BNS) and report field observations on zircon U–Pb ages, Lu–Hf isotopes, and the Al-in-hornblende barometry of quartz diorites from the Lameila pluton in western Tibet. Zircon from the quartz diorites yielded a LA-ICP-MS U–Pb age of 164 Ma. The zircon showed very positive εHf(t) values from 10.5 to 13.9, suggesting the Lameila pluton was likely sourced from the depleted-mantle wedge, which is in contrast with contemporary (164–161 Ma) volcanic rocks in the region that had negative εHf(t) values of −7.4 to −16.2 and a magma source from partial melting of subducted sediments. The Lameila pluton showed a temperature-corrected Al-in-hornblende pressure of 3.9 ± 0.8 kbar, corresponding to an emplacement depth of 13 ± 3 km. Therefore, the thickness of the Jurassic oceanic arc crust must have doubled since the initial growth of the oceanic arc on the BNO crust, with a crustal thickness of 6.5 km during the Middle Jurassic. In combination with previous works on volcanic rocks, this study further supports a two-subduction zone model in association with the BNO during the Middle Jurassic, namely, a north-dipping BNO–Qiangtang subduction zone and an oceanic subduction zone within the BNO. The latter oceanic subduction zone produced the depleted-mantle-derived Lameila pluton and the subducted sediment-derived volcanic rocks in the fore arc.

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Section: Tectonic Evolution Of the Bangong-nujiang Oceanmentioning

confidence: 99%

Section: Oceanic Arc Development and Two Contrasting Sources For Magmmentioning

confidence: 99%

Section: Oceanic Arc Development and Two Contrasting Sources For Magmmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

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Dating Oceanic Subduction in the Jurassic Bangong–Nujiang Oceanic Arc: A Zircon U–Pb Age and Lu–Hf Isotopes and Al-in-Hornblende Barometry Study of the Lameila Pluton in Western Tibet, China

2019

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Geochemistry and geochronology of Pengco subduction‐related ophiolites, Tibet: Implications for Dongkaco microcontinent in the Bangong–Nujiang suture zone

Shao

Song

et al. 2021

Geological Journal

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The identification of a microcontinent in Bangong-Nujiang suture zone (BNSZ) is important to understanding the tectonic evolution of Bangong-Nujiang Tethys Ocean (BNTO). Subduction-related ophiolite is one of the keys to discriminate a microcontinent in suture zones, which can be generated during the oceanic subduction beneath the microcontinent. Generally, ophiolites in the adjacent area of a microcontinent would show characteristics of a volcanic arc, while ophiolites in adjacent area of an ocean show characteristics of a fore-arc. North Pengco ophiolites (NPOs) and South Pengco ophiolites (SPOs) were collected in the central section of BNSZ, and dated at 115.0-111.5 Ma by SHRIMP II. According to their trace element characteristics, NPOs were determined to have formed at a setting of subduction-related volcanic arc and affected by slab-derived fluids or melts. The diagram based on the Ce versus Ce/Y shows that NPOs originated from the partial melting of spinel peridotites. On the other hand, SPOs were generated from the partial melting of ultra-depleted mantle at a setting of subduction-related fore-arc on the basis of extraordinarily low REEs summation and HFSEs (e.g., Zr, Ti, Nb and Ta), relatively high concentrations of compatible elements (e.g., Cr, Ni), large ratios of CaO/TiO 2 (37.67-437.50) and Al 2 O 3 /TiO 2 (20.78-424.50), which were also affected by slab-derived fluids. Based on the relative location of NPOs and SPOs, it reasonably proposed that a northward subduction of a minor oceanic basin had occurred at the Early Cretaceous, trigged by the Dongkaco microcontinent (DMC). In reverse, these ophiolites provide evidence for the existence of DMC in BNTO. Combining with other subduction-related ophiolites developed in BNSZ, BNTO might have comprised of several minor oceanic basins separated by some blocks like DMC in the central and west sections, rather than a unified ocean basin.

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An island arc origin of Jurassic plagiogranite in the Shiquanhe ophiolite, western Bangong Suture, Tibet: Zircon U–Pb chronology, geochemistry, and tectonic implications of Bangong Meso‐Tethys

Liu

Nayak

et al. 2021

Geological Journal

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The plagiogranites in ophiolites are minor in volume but can provide crucial information for the origin and tectonic evolution of ancient oceanic lithosphere. This paper presents the geochronology and geochemistry of a newly discovered plagiogranite in the Shiquanhe ophiolite, from the west end of the Shiquanhe‐Jiali ophiolite sub‐belt, Bangong Suture, central Tibet. Zircon U–Pb dating of two samples yields Middle Jurassic ages (167.4 ± 1.2 Ma and 167.5 ± 1.5 Ma). The plagiogranite has positive whole‐rock εNd(t) (4.2–4.9) and zircon εHf(t) (9.6–14.3) values, high Th/Nb ratios (0.6–2.8) but relatively low La/Nb ratios (0.9–9.9), indicating that it was possibly derived from a depleted mantle with the contribution of minor subducted sediments. The LREE‐enrichment but HREE‐flat patterns with negative Eu anomalies and negative Nb‐Ti anomalies resemble those of shear‐type plagiogranites, which mean that this rock was likely formed by partial melting of metabasite. Combined with the plagiogranite which does not exhibit chilled contacts against the Shiquanhe ophiolitic metabasite, suggests that the plagiogranite may have been derived from the associated ophiolitic metabasite. Geochemical calculating and modelling indicate that the plagiogranite was possibly produced by a low degree (<10%) partial melting of metabasite and replenished by minor sediments melts at low temperature (<800 °C) and low pressure (<0.1 GPa) conditions. The Shiquanhe plagiogranite, together with the contemporaneous Lagkorco plagiogranite in the same ophiolite sub‐belt, indicates that an intra‐oceanic island arc system was developed in the Bangong Meso‐Tethys during the Middle Jurassic.

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Origin and tectonic implications of the Shiquanhe high-Mg andesite, western Bangong suture, Tibet

Cited by 50 publications

References 82 publications

Dating Oceanic Subduction in the Jurassic Bangong–Nujiang Oceanic Arc: A Zircon U–Pb Age and Lu–Hf Isotopes and Al-in-Hornblende Barometry Study of the Lameila Pluton in Western Tibet, China

Dating Oceanic Subduction in the Jurassic Bangong–Nujiang Oceanic Arc: A Zircon U–Pb Age and Lu–Hf Isotopes and Al-in-Hornblende Barometry Study of the Lameila Pluton in Western Tibet, China

Geochemistry and geochronology of Pengco subduction‐related ophiolites, Tibet: Implications for Dongkaco microcontinent in the Bangong–Nujiang suture zone

An island arc origin of Jurassic plagiogranite in the Shiquanhe ophiolite, western Bangong Suture, Tibet: Zircon U–Pb chronology, geochemistry, and tectonic implications of Bangong Meso‐Tethys

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