The evolution of the Bangong–Nujiang Neo-Tethys ocean: Evidence from zircon U–Pb and Lu–Hf isotopic analyses of Early Cretaceous oceanic islands and ophiolites

Fan, Jian‐Jun; Cai, Li; Xie, Chao-Ming; Wang, Ming; Chen, Jingwen

doi:10.1016/j.tecto.2015.04.019

Cited by 78 publications

(39 citation statements)

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“…Moreover, the HMAs that form in these settings exhibit adakitic signatures and depleted isotopic compositions (Figure a). Although the collision could reduce the rate of under‐thrusting and allows the slab surface sufficient time to be heated and eventually melted [ Mo et al ., ; Huang et al ., ], the distribution of Middle‐Late Jurassic arc‐type rocks along the southwestern margin of the western Qiangtang terrane (Figure ) [ Li et al ., ; Liu et al ., a; Hao et al ., ], as well as the Middle Jurassic‐Early Cretaceous OIB rocks, suggest the BNO survived until the late Early Cretaceous [ Zhu et al ., ; Xu et al ., ; Fan et al ., ; Wang et al ., ]. Besides magmas generated by such conditions commonly are large scale which is stark inconsistent with the study area [ Mo et al ., ; Huang et al ., ].…”

Section: Discussionmentioning

confidence: 99%

“…However, like many ophiolites worldwide, there is still no consensus as to whether they are the remnants of a back‐arc basin, a fore‐arc basin, or a large oceanic basin [ Wang et al ., ; Baxter et al ., ; Xu et al ., ; Wang et al ., ]. Meanwhile, when does the subduction begin and the subduction polarity are also ambiguous [ Zhu et al ., ; Zhang et al ., , 2012; Fan et al ., ].…”

Section: Introductionmentioning

confidence: 99%

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Sediment melting during subduction initiation: Geochronological and geochemical evidence from the Darutso high‐Mg andesites within ophiolite melange, central Tibet

Zeng

Chen

et al. 2016

Geochem Geophys Geosyst

111

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In addition to fluids, the concept of sediment‐derived melts infiltrating the fore‐arc mantle during subduction initiation has been proposed based on studies of modern subduction zones and ophiolite mélange. However, outcrops that contain the products of such melts are rare, especially in conjunction with boninite. New U‐Pb zircon dating reveals that the Darutso volcanic rocks (DVRs) within ophiolitic mélange in the Beila area, central Tibet, crystallized at ∼164–162 Ma. This is the first recognition of Jurassic volcanic rocks in the middle section of the Bangong‐Nujiang Suture Zone. Geochemically, the DVRs are high‐Mg andesites with moderate SiO2 (59.03–63.62 wt %) and high MgO (3.74–6.53 wt %), Cr (up to 395 ppm), and Mg# (50.3–67.9). They also have high Th contents, (La/Sm)N ratios, and (87Sr/86Sr)i values (0.7085–0.7147); low Ba/Th, U/Th, and Sr/Y ratios; and negative values of εNd(t) (−8.7 to −9.8) and zircon εHf(t) (−7.4 to −9.9). The εNd(t) values of the DVRs overlap those of regional sediments. Detailed analyses of these geochemical characteristics indicate that the DVRs were derived from partial melting of subducted sediments and subsequent interaction with overlying mantle peridotite in a shallow and hot setting. In combination with the regional geology, in particular adjacent ophiolites that contain MORB‐like and boninite mafic lavas, these rocks collectively recorded the evolution of a fore‐arc setting during the initiation of the northward subduction of the south branch of the Bangong‐Nujiang Ocean. Therefore, the results provide direct evidence for sediment melting during subduction initiation and constrain the Jurassic tectonic evolution of the Lhasa terrane.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Sediment melting during subduction initiation: Geochronological and geochemical evidence from the Darutso high‐Mg andesites within ophiolite melange, central Tibet

Zeng

Chen

et al. 2016

Geochem Geophys Geosyst

111

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“…In recent years, numerous geochronological data have been obtained along the BNSZ (J. J. Fan et al, , b; Tang, Zhai, Hu, Xiao, & Wang, ; B. D. Wang et al, ; Xie, Li, Li, et al, ; M. J. Xu et al, ; Y. X. Zhang, Li, et al, ; X. Z. Zhang, Wang, et al, ).…”

Section: Discussionmentioning

confidence: 99%

Collisional processes between the Qiangtang Block and the Lhasa Block: Insights from structural analysis of the Bangong–Nujiang Suture Zone, central Tibet

Guo

et al. 2019

Geological Journal

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The Bangong–Nujiang Suture Zone (BNSZ) is one of the main suture zones in the Tibetan Plateau and indicates the existence of the Bangong–Nujiang Neo‐Tethys Ocean (BNO). It was formed by the collision between the Qiangtang and Lhasa blocks after the closure of the BNO. However, its evolutionary processes and subduction polarity remain controversial. Research on the BNSZ is of great significance for exploring plate tectonic evolution and ocean–continent connection. The scarcity of the BNSZ structural data is one of the most important reasons for the debate of the BNO tectonic evolution. Based on structural analysis in the field and combined with previous petrology and palaeomagnetic data, this paper has determined that the closure time of the BNO is progressive and scissor‐like, from Middle Jurassic in the east to Early Cretaceous in the middle and late Early Cretaceous to early Late Cretaceous in the west. There was a three‐stage deformation in the BNSZ: (a) N–S‐directed compression induced by the initial collision; (b) WNW–directed transpression related to the stress adjustment; and (c) NE–SW‐directed compression caused by the low‐angle NE‐directed subduction of the Indus–Yarlung Zangbo Ocean. The different structural pattern along the eastern segment of the BNSZ may have resulted from orogenic bending due to the later Himalayan Orocline caused by the India–Eurasia collision in the Cenozoic.

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“…The thin zoning in cathode‐luminescence images is typical of zircons crystallizing from felsic rather than from mafic igneous lavas, because the latter contains crystallizing zircons of broader bands (Rubatto & Gebauer, ). And in the Zhonggang oceanic island, the foreign zircon ages older than the Cretaceous occupy 74% in number and display multiple peaks (Fan et al, ). This fact indicates contamination of continental crust materials and cannot reconcile with the truth of an oceanic island which is too far away from continent crust to be contaminated.…”

Section: Discussionmentioning

confidence: 99%

Reply to Comment by W.‐Y. Chen et al. on “Sedimentary and Tectonic Evolution of the Southern Qiangtang Basin: Implications for the Lhasa–Qiangtang Collision Timing”

2018

JGR Solid Earth

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The evolution of the Bangong–Nujiang Neo-Tethys ocean: Evidence from zircon U–Pb and Lu–Hf isotopic analyses of Early Cretaceous oceanic islands and ophiolites

Cited by 78 publications

References 32 publications

Sediment melting during subduction initiation: Geochronological and geochemical evidence from the Darutso high‐Mg andesites within ophiolite melange, central Tibet

Sediment melting during subduction initiation: Geochronological and geochemical evidence from the Darutso high‐Mg andesites within ophiolite melange, central Tibet

Collisional processes between the Qiangtang Block and the Lhasa Block: Insights from structural analysis of the Bangong–Nujiang Suture Zone, central Tibet

Reply to Comment by W.‐Y. Chen et al. on “Sedimentary and Tectonic Evolution of the Southern Qiangtang Basin: Implications for the Lhasa–Qiangtang Collision Timing”

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