The Godzilla Megamullion, the largest oceanic core complex on the earth: a historical review
The Godzilla Megamullion, the largest oceanic core complex on the earth: a historical review
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DOI：
10.1111/iar.12116
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发表时间：
2016-05
期刊：
影响因子：
1.5
通讯作者：
Y. Ohara
中科院分区：
文献类型：
--
作者：
Y. Ohara
哥斯拉巨型地幔柱是地球上已知最大的大洋核杂岩（OCC），位于菲律宾海的帕里西维拉海盆。本文首次回顾了哥斯拉巨型地幔柱的研究历史，将其分为三个主要阶段：（i）日本扩展大陆架调查计划之前的早期研究；（ii）日本扩展大陆架调查计划期间发现大洋核杂岩的研究；（iii）发现之后的航次研究。早期研究包括对西南太平洋美国海图的解读以及深海钻探计划航次（DSDP第6、31和59航段）的现场调查。早期研究确认了帕里西维拉裂谷（帕里西维拉海盆已灭绝的扩张轴）的存在，并建立了目前被广泛接受的菲律宾海随着弧后扩张和岛弧迁移向东推进而演化的模型。对帕里西维拉海盆的现代认识来自日本的扩展大陆架调查计划。该计划揭示了超镁铁岩石学以及海盆的两阶段演化模型。基于这些结果，2001年发现了哥斯拉巨型地幔柱。发现之后的航次研究进一步揭示了大洋核杂岩的重要特征，例如大量含斜长石的橄榄岩的存在，以及辉长糜棱岩和超糜棱岩中变形微观结构以及斜长石和角闪石成分的系统性时间变化。辉长岩和浅色岩的锆石U - Pb年龄表明，帕里西维拉海盆扩张的末期阶段伴随着哥斯拉巨型地幔柱的形成，扩张速率显著下降且不对称。大洋核杂岩的估计剥蚀速率约为2.5厘米/年，明显慢于之前基于约束较差的磁性数据的估计。
The Godzilla Megamullion is the largest known oceanic core complex (OCC) on the Earth, located in the Parece Vela Basin in the Philippine Sea. In this article, the history of Godzilla Megamullion study is reviewed for the first time, dividing it into three major phases: (i) the early studies done before Japan's extended continental shelf survey program; (ii) the studies during Japan's extended continental shelf survey program that discovered the OCC; and (iii) the studies by the post‐discovery cruises. The early studies included an interpretation of US nautical chart of the southwestern Pacific and the site surveys for Deep Sea Drilling Project cruises (DSDP Legs 6, 31 and 59). The early studies recognized the presence of the Parece Vela Rift, the extinct spreading axis of the Parece Vela Basin, and established the currently accepted model that the Philippine Sea evolved with eastward progression of backarc spreading and arc migration. The modern understanding of the Parece Vela Basin comes from Japan's extended continental shelf survey program. The program revealed the ultramafic petrology as well as a two‐stage evolution model of the basin. Following these results, the discovery of the Godzilla Megamullion was made in 2001. The studies by the post‐discovery cruises further revealed important characteristics of the OCC, such as the presence of abundant plagioclase‐bearing peridotite and the systematic temporal changes in both deformation microstructures and composition of plagioclase and amphibole in gabbroic mylonites and ultramylonites. Zircon U–Pb ages of gabboric and leucocratic rocks indicate that the terminal phase of Parece Vela Basin spreading was with a significant decline in spreading rate and asymmetry accompanying formation of the Godzilla Megamullion. The estimated denudation rate of the OCC was approximately 2.5 cm/yr; significantly slower than the previous estimate based on poorly constrained magnetic data.