Archean Tectonics of the Pilbara craton, Western Australia

西澳大利亚皮尔巴拉克拉通的太古代构造

• 批准号: 06041038
• 负责人: ISOZAKI Yukio
• 金额: $ 2.88万
• 依托单位: TOKYO INSTITUTE OF TECHNOLOGY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for international Scientific Research
• 财政年份: 1994
• 资助国家: 日本
• 起止时间: 1994 至 无数据
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-06041038/
• 关键词: accretionary complex; chert; MORB; BIF; OIB; hydrothermal activity; plume; orogenic belt

Archean (3.5-2.5 Ga) sedimentary rocks in the Pilbara craton, Western Australia, have been regarded as succesive sequences accumulated in situ on continetal crust. Present research project has clarified, however, that these Archean sedimentary complexes are ancient accretionary complexes formed at subduction zones. Detailed field research was conducted in the Cleaverville, North Pole, Marble Bar, Camel Creek, and Beasley River areas in the granite/greenstone belts of the Pilbara craton, and following results were newly obtained.Recognition of duplex structure and oceanic plate stratigraphy of component rocktypes proved the occurrence of Archean acrretionary complex. This find indicates that plate tectonics including subduction of oceanic plate was working already at 3.5 Ga (mid-Archean time), and that the Archean granite/greenstone belt represents subduction-related Cordilleran-type orogenic belt. Furthermore, it implies that Archean granite/greensone belts in other cratons can be all … More re-interpreted as Cordilleran-type orogenic belts.On the other hand, some peculiar characteristics of Archean accretionary complex can be documented as follows ; 1) Archean MORB in accretionary complex is fairly thicker than those in Phanerozoic equivalents, 2) occurence of komatiitic greenstones which is absent in Phanerozoic example, and 3) metalliferous pelagic sediments including barite deposits. What was also clarified is a considerable variation in Archean accretionary complexes including komattitic grenstone (probably of oceanic plateau origin) -dominant complex, and those with strong alteration by hydrothermal venting associated with barite units. In addition, the so-called oldest (3.5 Ga) stromotolite was revealed to be a deep-sea hydrothermal deposits associated with barite.The above-mentioned results are all new to this study field, and the present project team is now trying to publish these in international journals as soon as possible. We would like to appreciate the Ministry of education and culture of Japan for the support on this project. Less

西澳大利亚州皮尔巴拉克拉通太古宙(3.5~2.5Ga)沉积岩被认为是陆壳原地堆积的层序。然而，目前的研究表明，这些太古宙沉积杂岩是形成于俯冲带的古老增生杂岩。在皮尔巴拉克拉通花岗岩/绿岩带的克利弗维尔、北极、大理石坝、骆驼溪和比斯利河地区进行了详细的野外研究，取得了以下新成果：双重构造的识别和成分岩石类型的洋板地层证实了太古宙区域杂岩的存在。这一发现表明，包括大洋板块俯冲在内的板块构造在3.5Ga(太古宙中期)已经开始活动，太古代花岗岩/绿岩带代表了与俯冲有关的科迪勒型造山带。此外，它还意味着其他克拉通中的太古宙花岗岩/绿松带可能都是…。另一方面，太古宙增生杂岩具有如下特征：1)增生杂岩中太古宙MORB比显生宙相当厚，2)出现显生界中没有的科马提质绿岩，3)含金属远洋沉积，包括重晶石矿床。此外，还阐明了太古宙增生杂岩中存在着相当大的变化，包括以科马提质花岗岩(可能来自大洋高原)为主的杂岩，以及与重晶石单元有关的热液喷发强烈蚀变的杂岩。此外，所谓最古老(3.5Ga)的叠层石被发现是与重晶石有关的深海热液矿床。上述结果在该研究领域都是新的，本项目组正在努力尽快在国际期刊上发表这些结果。我们感谢日本文部省对这一项目的支持。较少

项目成果

Y.Isozaki, S.Maruyama: "Project "Earth History Column"" Earth Monthly. Spec.vol.10. 20-25 (1994)

Y.Isozaki，S.Maruyama：“项目“地球历史专栏””地球月刊。

S.Maruyama, M.Kumazawa, Y.Isozaki and T.Seno: "A New Summary of Earth History" Earth Monthly. Spec.vol.10. 14-19 (1994)

S.Maruyama、M.Kumazawa、Y.Isozaki 和 T.Seno：“地球历史的新概述”地球月刊。

丸山茂徳: "マントルの進化をよむ-全地球史解読-" 月刊地球. vol.17,NO.3. 133-135 (1995)

Shigenori Maruyama：“解读地幔的演化——解读整个地球的历史——”地球月刊第17卷，第133-135期（1995）。

太田宏,丸山茂徳,磯崎行雄: "過去の造山帯中に産する火山岩からマントルの進化を読む試み" 月刊地球. vol.17,NO.3. 164-170 (1995)

Hiroshi Ota、Shigenori Maruyama、Yukio Isozaki：“尝试了解过去造山带产生的火山岩的地幔演化”，《地球月刊》第 17 卷，第 164-170 期（1995 年）。

磯崎行雄・丸山茂徳: "地球史柱状図計画" 月刊地球. 号外NO.10. 20-25 (1994)

矶崎由纪夫和丸山茂德：《地球历史专栏计划》地球月刊特刊第 10 期 20-25（1994 年）