Zircon and apatite thermochronology of the Nankai Trough accretionary prism and trench, Japan: Sediment transport in an active and collisional margin setting
Zircon and apatite thermochronology of the Nankai Trough accretionary prism and trench, Japan: Sediment transport in an active and collisional margin setting
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DOI：
10.1002/tect.20033
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发表时间：
2013-06
期刊：
影响因子：
4.2
通讯作者：
P. Clift;A. Carter;Uisdean Nicholson;H. Masago
中科院分区：
文献类型：
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作者：
P. Clift;A. Carter;Uisdean Nicholson;H. Masago
南海增生复合体是日本西南部增生复合体的最新补充，并在其建造过程中保存了沉积物通量的记录。在这项研究中，我们使用U-Pb锆石和裂变径迹分析从南海海槽的弧前和海沟的沉积物中的锆石和磷灰石，以及来自日本西南部的河流，检查自中中新世以来的边缘折返历史。现代河流显示出由中生代-始新世Shimanto和Sanbagawa增生复合体的侵蚀主导的通量。只有排干伊豆和本州弧之间碰撞区的富士河在显示出更快的挖掘方面是独一无二的。沿九州近海边缘沿着350-500 km未发现伊豆-本州碰撞的沉积物，表明沿沿着-走向的沉积物搬运有限。沉积物沉积自2马的中沟斜坡近海四国室户半岛（ODP网站1176）和下斜坡沟向熊野盆地（IODP网站C 0006 E和C 00007 E）的主要来源，在Shimanto和Sanbagawa复杂的现代河流。在5 Ma之前，更多的沉积物来自更北部的更缓慢的挖掘地形，距离海沟轴线约350 km。大约9.4 Ma，~1800 Ma的U-Pb锆石年龄表明暴露于本州北方的华北盆地的侵蚀增强。在中新世中期，约15.4 Ma，沉积物来自更广泛的地区，包括扬子江（U-Pb年龄约800 Ma）。我们认为，这种增强的集水区可能反映了长江在冲绳海槽10 Ma裂陷和帕劳-九州海岭迁移之前对四国盆地补给的影响，形成了一个运输障碍。南海海槽物源对中生代物源的限制，部分反映了中中新世以来四万十杂岩和三八川杂岩的持续隆升。
The Nankai accretionary complex is the most recent addition to the accretionary complexes of southwest Japan and has preserved a record of sediment flux to the trench during its construction. In this study, we use U‐Pb zircon and fission track analysis of both zircons and apatites from sediments taken from the forearc and trench of the Nankai Trough, as well as rivers from southwest Japan to examine the exhumation history of the margin since the Middle Miocene. Modern rivers show a flux dominated by erosion of the Mesozoic‐Eocene Shimanto and Sanbagawa accretionary complexes. Only the Fuji River, draining the collision zone between the Izu and Honshu arcs, is unique in showing much faster exhumation. Sediment from the Izu‐Honshu collision is not found 350–500 km along the margin offshore Kyushu indicating limited along‐strike sediment transport. Sediment deposited since 2 Ma on the midtrench slope offshore the Muroto Peninsula of Shikoku (ODP Site 1176) and on the lower slope trenchward of the Kumano Basin (IODP Sites C0006E and C00007E) shares the dominant source in the Shimanto and Sanbagawa complexes seen in the modern rivers. Prior to 5 Ma, additional sediment was being sourced from further north in more slowly exhumed terrains, ~350 km from the trench axis. Around 9.4 Ma, U‐Pb zircon ages of ~1800 Ma indicate enhanced erosion from the North China Craton, exposed in northern Honshu. In the middle Miocene, at ~15.4 Ma, the sediment was being derived from a much wider area including the Yangtze Craton (U‐Pb ages ~800 Ma). We suggest that this enhanced catchment may have reflected the influence of the Yangtze River in supplying into the Shikoku Basin prior to rifting of the Okinawa Trough at 10 Ma and migration of the Palau‐Kyushu Ridge to form a barrier to transport. The restriction of Nankai Trough provenance to Mesozoic source partly reflects continued uplift of the Shimanto and Sanbagawa complexes since the Middle Miocene.