Chemical and isotopic composition of lavas from the Northern Mariana Trough: Implications for magmagenesis in back-arc basins

被引:291
|
作者
Gribble, RF
Stern, RJ
Newman, S
Bloomer, SH
O'Hearn, T
机构
[1] Univ Texas, Ctr Lithospher Studies, Richardson, TX 75083 USA
[2] CALTECH, Div Geol & Planetary Sci, Pasadena, CA 91125 USA
[3] Oregon State Univ, Dept Geosci, Corvallis, OR 97331 USA
[4] Smithsonian Inst, Washington, DC 20560 USA
关键词
arc magma; back-arc basin basalt; isotope geochemistry; Mariana Islands; trace elements;
D O I
10.1093/petrology/39.1.125
中图分类号
P3 [地球物理学]; P59 [地球化学];
学科分类号
0708 ; 070902 ;
摘要
We report the results of a geochemical and isotopic study of mostly basaltic glasses recovered from 25 dredge stations along the northernmost 500 km of the Mariana Trough extension axis. The distribution of samples links regions of seafloor spreading to the south with regions farther north where a progression of rifting styles accompanies the earliest stages of bark-arc basin extension. Petrographic, chemical and isotopic compositions of igneous rocks reflect the changing styles of extension, with typical back-arc basin basalts in the south which become increasingly similar to arc lavas to the north. Felsic lavas also appear along the extensional axis in the north. Glassy, sparsely phyric basalts characterize regions of seafloor spreading. Felsic lavas and porphyritic basalts occur in the northern, rifting portion. Geochemical and isotopic compositions distinguish between mature an portions (Ce/Pb <10, Ba/La >20; Pb-206/Pb-204 >18.5, Sr-87/Sr-86 >0.7032, epsilon(Nd) < + 8) and regions of back-arc spreading (Ce/Pb >10, Ba/La <20; Pb-206/Pb-204 <18.9, Sr-87/Sr-86 <0.7032, epsilon(Nd) > + 7). Samples from along the extensional axis of the northern Mariana Trough show progressive changes in chemical and isotopic compositions, from back-arc basin basalts that formed by seafloor spreading northward through increasingly arc-like basalts, until lavas that are in distinguishable from arc lavas are encountered in the northernmost portion of the rift. Batch-melting models indicate that northernmost degrees of melting, with 13 +/- 5% melting where seafloor spreading occurs, doubling to 28 +/- 8% for the northernmost part of the rift axis. The greater degree of melting in the north reflects the greater amount of water added to the mantle source, reflecting the arc-like nature of the source region and melt generation style characteristic of the initial stages of back-arc basin formation. Our data indicate that F = 0.44W + 0.07, where F is the degree of mantle melting and W is the percent water in the mantle. 'True' back-arc basin basalts are generated by adiabatic decompression associated with mantle upwelling in mature extensional settings. Eruption of 'true' bark-arc basin basalts accompanies seafloor spreading, which begins when the basin is 100-150 km wide. The arc is disrupted during early rift formation, because arc magmatism is captured by the extension axis, but the generation of an melts by hydrous melting of the mantle wedge continues whether or not back-an extension is occurring. Back-arc basin seafloor spreading requires development of an upwelling mantle flow regime, allowing melting by adiabatic decompression, similar to that responsible for mid-ocean ridge basalt (MORB). The arc begins to re-form once extension progresses nearly to the point of seafloor spreading.
引用
收藏
页码:125 / 154
页数:30
相关论文
共 50 条
  • [2] ENRICHED BACK-ARC BASIN BASALTS FROM THE NORTHERN MARIANA TROUGH - IMPLICATIONS FOR THE MAGMATIC EVOLUTION OF BACK-ARC BASINS
    STERN, RJ
    LIN, PN
    MORRIS, JD
    JACKSON, MC
    FRYER, P
    BLOOMER, SH
    ITO, E
    [J]. EARTH AND PLANETARY SCIENCE LETTERS, 1990, 100 (1-3) : 210 - 225
  • [3] Geochemistry of axial lavas from the mid- and southern Mariana Trough, and implications for back-arc magmatic processes
    Quanshu Yan
    Pingyang Zhang
    Ian Metcalfe
    Yanguang Liu
    Shiying Wu
    Xuefa Shi
    [J]. Mineralogy and Petrology, 2019, 113 : 803 - 820
  • [4] Geochemistry of axial lavas from the mid- and southern Mariana Trough, and implications for back-arc magmatic processes
    Yan, Quanshu
    Zhang, Pingyang
    Metcalfe, Ian
    Liu, Yanguang
    Wu, Shiying
    Shi, Xuefa
    [J]. MINERALOGY AND PETROLOGY, 2019, 113 (06) : 803 - 820
  • [5] No measurable calcium isotopic variations of back-arc lavas across the Okinawa Trough
    Chen, Xue-Gang
    Wang, Jian-Qiang
    Cao, Hai-Gang
    Wu, Jia-Yi
    Li, Xiaohu
    Ding, Yi
    Zhu, Zhi-Min
    Li, Zheng-Gang
    [J]. MARINE GEOLOGY, 2022, 452
  • [6] Noble gases in pillow basalt glasses from the northern Mariana Trough back-arc basin
    Ikeda, Y
    Nagao, K
    Stern, RJ
    Yuasa, M
    Newman, S
    [J]. ISLAND ARC, 1998, 7 (03) : 471 - 478
  • [7] Geodetic evidence of back-arc spreading in the Mariana trough
    Kato, T
    Beavan, J
    Matsushima, T
    Kotake, Y
    Camacho, JT
    Nakao, S
    [J]. GEOPHYSICAL RESEARCH LETTERS, 2003, 30 (12)
  • [8] MARIANA TROUGH LAVAS FROM 18-DEGREES-N - IMPLICATIONS FOR THE ORIGIN OF BACK ARC BASIN BASALTS
    SINTON, JM
    FRYER, P
    [J]. JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH AND PLANETS, 1987, 92 (B12): : 12782 - 12802
  • [9] Sedimentary, volcanic, and tectonic processes of the central Mariana Arc: Mariana Trough back-arc basin formation and the West Mariana Ridge
    Oakley, A. J.
    Taylor, B.
    Moore, G. F.
    [J]. GEOCHEMISTRY GEOPHYSICS GEOSYSTEMS, 2009, 10
  • [10] Influence of subduction components on magma composition in back-arc basins: a comparison between the Mariana and Okinawa troughs
    Zhao, Guangtao
    Luo, Wenqiang
    Lai, Zhiqing
    Tian, Liyan
    Xu, Cuiling
    [J]. GEOLOGICAL JOURNAL, 2016, 51 : 357 - 367