DOI: 10.1016/j.epsl.2017.11.016
Scopus记录号: 2-s2.0-85035093443
论文题名: On the development of the calc-alkaline and tholeiitic magma series: A deep crustal cumulate perspective
作者: Chin E.J. ; Shimizu K. ; Bybee G.M. ; Erdman M.E.
刊名: Earth and Planetary Science Letters
ISSN: 0012821X
出版年: 2018
卷: 482 起始页码: 277
结束页码: 287
语种: 英语
英文关键词: arc
; calc-alkaline trend
; cumulates
; iron
; mid-ocean ridge
; tholeiitic trend
Scopus关键词: Iron
; Melting
; Oceanography
; Oxidation
; Reservoirs (water)
; Submarine geology
; calc-alkaline trend
; Crustal contamination
; cumulates
; Low-pressure conditions
; Mid ocean ridge basalts
; Mid-ocean ridges
; tholeiitic trend
; Upper continental crust
; Structural geology
; calc alkaline rock
; continental crust
; cumulate
; iron
; magma chamber
; mid-ocean ridge
; tholeiite
英文摘要: Two distinct igneous differentiation trends – the tholeiitic and calc-alkaline – give rise to Earth's oceanic and continental crust, respectively. Mantle melting at mid-ocean ridges produces dry magmas that differentiate at low-pressure conditions, resulting in early plagioclase saturation, late oxide precipitation, and Fe-enrichment in mid-ocean ridge basalts (MORBs). In contrast, magmas formed above subduction zones are Fe-depleted, have elevated water contents and are more oxidized relative to MORBs. It is widely thought that subduction of hydrothermally altered, oxidized oceanic crust at convergent margins oxidizes the mantle source of arc magmas, resulting in erupted lavas that inherit this oxidized signature. Yet, because our understanding of the calc-alkaline and tholeiitic trends largely comes from studies of erupted melts, the signals from shallow crustal contamination by potentially oxidized, Si-rich, Fe-poor materials, which may also generate calc-alkaline rocks, are obscured. Here, we use deep crustal cumulates to “see through” the effects of shallow crustal processes. We find that the tholeiitic and calc-alkaline trends are indeed reflected in Fe-poor mid-ocean ridge cumulates and Fe-rich arc cumulates, respectively. A key finding is that with increasing crustal thickness, arc cumulates become more Fe-enriched. We propose that the thickness of the overlying crustal column modulates the melting degree of the mantle wedge (lower F beneath thick arcs and vice versa) and thus water and Fe3+ contents in primary melts, which subsequently controls the onset and extent of oxide fractionation. Deep crustal cumulates beneath thick, mature continental arcs are the most Fe-enriched, and therefore may be the “missing” Fe-rich reservoir required to balance the Fe-depleted upper continental crust. © 2017 Elsevier B.V. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/110108
Appears in Collections: 影响、适应和脆弱性 气候变化事实与影响
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作者单位: Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA, United States; Department of Terrestrial Magnetism, Carnegie Institution of Washington, Washington, DC, United States; School of Geosciences, University of the Witwatersrand, Johannesburg, South Africa; Department of Earth, Environmental and Planetary Sciences, Rice University, Houston, TX, United States
Recommended Citation:
Chin E.J.,Shimizu K.,Bybee G.M.,et al. On the development of the calc-alkaline and tholeiitic magma series: A deep crustal cumulate perspective[J]. Earth and Planetary Science Letters,2018-01-01,482