Isotope characteristics of submarine lavas from the Philippine Sea: implications for the origin of arc and basin magmas of the Philippine tectonic plate
Isotope characteristics of submarine lavas from the Philippine Sea: implications for the origin of arc and basin magmas of the Philippine tectonic plate
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DOI：
10.1016/0012-821x(91)90077-u
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发表时间：
1991-11
影响因子：
5.3
通讯作者：
R. Hickey‐Vargas
中科院分区：
文献类型：
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作者：
R. Hickey‐Vargas
对深海钻探项目第31、58和59航段从菲律宾构造板块回收的火成岩进行了Sr、Nd和Pb同位素比值分析。样品包括来自西菲律宾盆地、大东盆地和宾汉隆起（40-60百万年）的岩石，帕劳-九州海脊（29-44百万年）以及Parece Vela和Shikoku盆地（17-30百万年）。来自西菲律宾盆地、帕雷西贝拉盆地和四国盆地的样品类似于MORB（洋中脊玄武岩），87 Sr/86 Sr = 0.7026− 0.7032，143 Nd/144 Nd = 0.51300−0.51315，206 Pb/204 Pb = 17.8−18.1。来自大东盆地和宾汉隆起的样品类似于OIB（洋岛玄武岩），87 Sr/86 Sr = 0.7038− 0.7040，143 Nd/144 Nd = 0.51285− 0.51291和206 Pb/204 Pb = 18.8−19.2。所有这些岩石的207 Pb/204 Pb和208 Pb/204 Pb值均高于北方回归线（NHRL），δ 207 Pb值为0至+6，δ 208 Pb值为+32至+65。帕劳-九州海岭的熔岩是一个残余岛弧，其87 Sr/86 Sr = 7032− 0.7035，143 Nd/144 Nd = 0.51308− 0.51310，206 Pb/204 Pb = 18.4−18.5。不像盆地岩浆爆发之前和之后，这些熔岩情节沿着NHRL和铅同位素比值类似于现代太平洋板块MORB的。这一特点是共享的其他帕劳-九州弧火山岩已被采样的马里亚纳前弧的淹没和陆上部分。至少有四个地球化学不同的岩浆源，这些菲律宾板块岩浆。盆地岩浆流出源1和源2，源1是受EMI污染的MORB-地幔源（富集地幔组分1 [31]），源2是具有EMII某些特征的OIB样地幔源（富集地幔组分2 [31]）。弧熔岩来源于源3，一个MORB源或残留地幔，包括来自俯冲洋壳的Sr和Pb，源4，MORB源或残留地幔，包括具有HIMU特征的组分（具有高U/Pb的地幔组分[31]）。这些相同的来源可以解释许多菲律宾板块弧和盆地熔岩的同位素特征。这些源区中与DUPAL异常有关的富集组分可能是菲律宾板块位于南半球60 m. y. b. p.时从地幔深部引入软流圈的。
Igneous rocks from the Philippine tectonic plate recovered on Deep Sea Drilling Project Legs 31, 58 and 59 have been analyzed for Sr, Nd and Pb isotope ratios. Samples include rocks from the West Philippine Basin, Daito Basin and Benham Rise (40–60 m.y.), the Palau-Kyushu Ridge (29–44 m.y.) and the Parece Vela and Shikoku basins (17–30 m.y.). Samples from the West Philippine, Parece Vela and Shikoku basins are MORB (mid-ocean ridge basalt)-like with87Sr/86Sr= 0.7026−0.7032,143Nd/144Nd= 0.51300−0.51315, and206Pb/204Pb= 17.8−18.1. Samples from the Daito Basin and Benham Rise are OIB (oceanic island basalt)-like with87Sr/86Sr= 0.7038−0.7040,143Nd/144Nd= 0.51285−0.51291and206Pb/204Pb= 18.8−19.2. All of these rocks have elevated207Pb/204Pband208Pb/204Pbcompared to the Northern Hemisphere Regression Line (NHRL) and haveδ207Pbvalues of 0 to +6 andδ208Pbvalues of +32 to +65. Lavas from the Palau-Kyushu Ridge, a remnant island arc, have87Sr/86Sr= 7032−0.7035,143Nd/144Nd= 0.51308−0.51310and206Pb/204Pb= 18.4−18.5. Unlike the basin magmas erupted before and after them, these lavas plot along the NHRL and have Pb-isotope ratios similar to modern Pacific plate MORB's. This characteristic is shared by other Palau-Kyushu Arc volcanic rocks that have been sampled from submerged and subaerial portions of the Mariana fore-arc.At least four geochemically distinct magma sources are required for these Philippine plate magmas. The basin magmas tap Source 1, a MORB-mantle source that was contaminated by EMI (enriched mantle component 1 [31]) and Source 2, an OIB-like mantle source with some characteristics of EMII (enriched mantle component 2 [31]). The arc lavas are derived from Source 3, a MORB-source or residue mantle including Sr and Pb from the subducted oceanic crust, and Source 4, MORB-source or residue mantle including a component with characteristics of HIMU (mantle component with highU/Pb[31]). These same sources can account for many of the isotopic characteristics of recent Philippine plate arc and basin lavas. The enriched components in these sources which are associated with the DUPAL anomaly were probably introduced into the asthenosphere from the deep mantle when the Philippine plate was located in the Southern Hemisphere 60 m.y.b.p.