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REE and Nd-Sr isotope provenance signatures in clastic sedimentary terranes and geological evolution of the Asia-Pacific margin

碎屑沉积地体中的 REE 和 Nd-Sr 同位素物源特征及亚太边缘的地质演化

基本信息

批准号：
13440147
负责人：
ROSER Barry・P
金额：
$ 5.89万
依托单位：
Shimane University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2001
资助国家：
日本
起止时间：
2001 至 2004
项目状态：
已结题

项目摘要

Sandstone-mudstone suites from major terranes in Honshu, Hokkaido and Korea show significant contrasts in whole rock geochemical compositions. In Honshu, the Shimanto-Tanabe, Sambagawa, and Kurosegawa suites show major, trace, and rare earth element signatures typical of relatively evolved CIA or ACM sediments. Chondrite-normalized REE patterns are fractionated, with average La_N/Yb_N of 10.4-10.9,8.2, and 9.2, and Gd_N/Yb_N ratios of 1.72-1.33,1.45, and 1.71, respectively. The lower Gd_N/Yb_N ratios suggest concentration of zircon and garnet. Negative Eu anomalies occur in all three suites (average Eu/Eu^* 0.77-0.73,0.63, and 0.79, respectively). High La_N/Yb_N ratios (average 11.00) and larger negative Eu/Eu anomalies (0.64) in the silicic Oshima terrane (Hokkaido) indicate a relatively mature source. Lower La_N/Yb_N and Eu/Eu^* (average 9.74 and 0.69) in lower Yezo Group-Idonnappu Zone rocks decrease further in the upper part (6.76 and 0.78), reflecting a greater mafic component. Av … More erage La_N/Yb_N ratio (13.5) in the Gyeongsang Supergroup (Korea) is greater than in the correlative Kanmon Group (8.8), but average Eu/Eu* values are comparable (0.78-0.79). Nd model (ages from the Shimanto, Sambagawa. Oshima and Yezo-Idonnappu terranes contrast significantly. Shimanto model ages range from 0.74 to 1.6 Ga, although most lie between 1.0-1.4 Ga, intermediate between potential Ryoke and Higo Ryoke terrane sources. Two Sambagawa schists yield comparable model ages of 1.04 and 1.2 Ga, lending support to a Shimanto protolith. Oshima terrane model ages are significantly older (1.44-1.85 Ga), comparable with values for the Yangtze craton, their probable source. Model ages in the lower Yezo-Idonnappu suite are consistently younger (1.05-1.31 Ga), and are younger still (0.71-0.93 Ga) in upper Yezo-Idonnappu rocks, possibly reflecting contributions from oceanic crust recycled within the accretionary complex. Normalization of elemental abundances against average Japan Orogenic are upper crust(JOAUC) shows negative anomalies for some elements (e.g.Fe,Mn,Mg,Ca,P,Sc,V,Cr and Ni) in some suites, although the REE and HFSE generally compare well. Depletion is most marked in the Oshima, Yezo-Idonnappu, and Shimanto terranes, and in sandstones compared to mudstones. The anomalies suggest the JOAUC average could be amended for some elements. Less

日本本州、北海道和韩国主要火山岩的砂岩-泥岩套在全岩地球化学成分上表现出明显的差异。在本州，Shimanto-Tanabe，Sambagawa和Kurosegawa套房显示出相对演化的CIA或ACM沉积物的典型的主要，微量和稀土元素的签名。球粒陨石标准化稀土元素分馏模式的La_N/Yb_N平均值分别为10.4- 10.9、8.2和9.2，Gd_N/Yb_N平均值分别为1.72- 1.33、1.45和1.71。较低的Gd_N/Yb_N比值表明锆石和石榴石的富集。三套岩系均出现Eu负异常（平均Eu/Eu^* 分别为0.77 ~ 0.73，0.63和0.79）。北海道大岛县的La_N/Yb_N比值较高（平均值为11.00），Eu/Eu负异常较大（0.64），表明源区较成熟。下耶佐群-伊多纳普带岩石的低La_N/Yb_N和Eu/Eu^*（平均值分别为9.74和0.69）在上部进一步降低（分别为6.76和0.78），反映出较高的镁铁质成分。Av ...更多信息庆尚超群（韩国）的La_N/Yb_N平均值（13.5）大于相关的关门群（8.8），但Eu/Eu ~* 平均值（0.78-0.79）相当。Nd模型（年龄来自Shimanto，Sambagawa。Oshima和Yezo-Idonnappu的对比明显。Shimanto模型的年龄范围从0.74到1.6 Ga，虽然大多数位于1.0-1.4 Ga之间，介于潜在的Ryoke和Higo Ryoke源之间。两个Sambagawa片岩产量可比模型年龄为1.04和1.2 Ga，贷款支持Shimanto原岩。大岛的模型年龄显着老（1.44-1.85 Ga），与扬子克拉通，其可能的来源值。模式年龄在较低的Yezo-Idonnappu套件是一贯年轻（1.05-1.31 Ga），和仍然年轻（0.71-0.93 Ga）在上部Yezo-Idonnappu岩石，可能反映了海洋地壳内的增生复合物再循环的贡献。元素丰度对平均日本造山带上地壳（JOAUC）的归一化显示负异常的一些元素（如铁，锰，镁，钙，磷，钪，钒，铬和镍）在某些套房，虽然稀土元素和HFSE一般比较好。与泥岩相比，消耗在大岛、叶佐-伊多纳普和四万托地区以及砂岩中最为显著。这些异常情况表明，联合作业AUC平均值可对某些要素进行修正。少