DOI: 10.1016/j.epsl.2021.117133
论文题名: An iron isotope perspective on back-arc basin development: Messages from Mariana Trough basalts
作者: Chen Y. ; Niu Y. ; Xue Q. ; Gao Y. ; Castillo P.
刊名: Earth and Planetary Science Letters
ISSN: 0012821X
出版年: 2021
卷: 572 语种: 英语
中文关键词: asthenospheric mantle
; back-arc basin basalts
; iron isotopes
; northern Mariana Trough
; sub-arc lithospheric mantle
英文关键词: Exploratory geochemistry
; Iron
; Isotopes
; Rare earth elements
; Rare earths
; Tectonics
; Trace elements
; Asthenospheric mantle
; Back-arc basin
; Back-arc basin basalts
; Incompatible element
; Iron isotopes
; Magmatisms
; Mariana troughs
; Northern mariana trough
; South-to-North
; Sub-arc lithospheric mantle
; Basalt
英文摘要: The geology and magmatism of the northern Mariana Trough (NMT) represent a type example for the development of a back-arc basin (BAB). It is a mature spreading center in the south and propagating northward via rifting of arc and rear arc lithosphere in response to trench retreat and overriding plate extension in space and time. It is thus essential to fully characterize its tectonomagmatic processes that are potentially of global significance. For this reason, we carried out a comprehensive geochemical study on basaltic samples (glasses) from the NMT axis from 17 to 23°N by analyzing a full suite of major and trace elements, Sr–Nd–Pb–Hf radiogenic isotopes and stable Fe isotopes. The Fe isotopes, in particular, have the potential to offer novel perspectives beyond the aforementioned geochemical variables. From south to north, the δ56Fe of the NMT basalts (NMTB) decrease systematically, varying from a MOR-like value of +0.12‰ to an arc-like value of 0.00‰. Importantly, incompatible element abundances and Sr–Nd–Pb–Hf isotope compositions of the NMTB also show systematic along-latitude variations. Positively correlated with δ56Fe, the abundances of fluid-insoluble elements (e.g., Nb, Ta, Zr, Hf, Ti and heavy rare earth elements) show the south-to-north decrease, suggesting that the NMTB δ56Fe systematics are inherited from the magma source variation. The source variation is most consistent with an asthenosphere source in the south and progressively more depleted harzburgitic lithosphere source of prior melt depletion towards north. On the other hand, there are scattered but significant enrichment trends towards north in terms of Sr–Nd–Pb–Hf radiogenic isotopes and fluid-soluble incompatible elements (e.g., Ba, Rb, Cs, Th, U, K, Pb, Sr and light rare earth elements), which is consistent with south-to-north increase in slab material (e.g., slab fluids, sediments etc.) contribution. These north-to-south magma source systematics defined by the NMTB can be readily understood as a tectonic response to the back-arc basin development with time from initial arc-magmatism dominated by sub-arc lithospheric mantle melting with significant slab material contributions to back-arc rifting and to back-arc spreading center magmatism characterized by increasing asthenospheric mantle melting, decreasing slab material contribution and diminishing sub-arc lithospheric mantle participation. This tectonic-magma source evolution in space and time is manifested by the snapshot of the NMTB magmatism in terms of the geology, petrology and geochemistry. The NMTB δ56Fe values and fluid-insoluble incompatible element abundances are unaffected by slab materials, but controlled by the harzburgitic residues of previous melt extraction depleted in these elements with low δ56Fe at the early arc-magmatism stage in the north and by the asthenosphere of MORB mantle characteristics in the south with well-developed back-arc spreading system. Importantly, these observations affirm the understanding that compositionally depleted and physically buoyant lithosphere is prerequisite as the overriding plate for subduction initiation at its edges. © 2021 The Author(s) Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/165433
Appears in Collections: 气候变化与战略
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作者单位: School of Ocean Sciences, China University of Geosciences, Beijing, 100083, China; China University of Geosciences, Beijing, 100083, China; Department of Earth Sciences, Durham University, Durham, DH1 3LE, United Kingdom; Laboratory for Marine Geology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266061, China; University of Chinese Academy of Sciences, Beijing, 100049, China; Research School of Earth Sciences, Australian National University, Canberra, ACT 2601, Australia; Scripps Institution of Oceanography, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0212, United States
Recommended Citation:
Chen Y.,Niu Y.,Xue Q.,et al. An iron isotope perspective on back-arc basin development: Messages from Mariana Trough basalts[J]. Earth and Planetary Science Letters,2021-01-01,572