Mid-Quaternary decoupling of sediment routing in the Nankai Forearc revealed by provenance analysis of turbiditic sands

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doi: 10.1007/s00531-014-1011-z
Author(s): Usman, Muhammed O.; Masago, Hideki; Winkler, Wilfried; Strasser, Michael
Author Affiliation(s): Primary:
Eidgenössische Technische Hochschule Zürich, Department of Earth Sciences, Zurich, Switzerland
Japan Agency for Marine-Earth Science and Technology, Japan
Volume Title: International Journal of Earth Sciences Geologische Rundschau
Source: International Journal of Earth Sciences = Geologische Rundschau, 103(4), p.1141-1161. Publisher: Springer International, Berlin, Germany. ISSN: 1437-3254 CODEN: GERUA3
Note: In English. 73 refs.; illus., incl. strat. cols., sect., 1 table, geol. sketch map
Summary: Coring during Integrated Ocean Drilling Program Expeditions 315, 316, and 333 recovered turbiditic sands from the forearc Kumano Basin (Site C0002), a Quaternary slope basin (Site C0018), and uplifted trench wedge (Site C0006) along the Kumano Transect of the Nankai Trough accretionary wedge offshore of southwest Japan. The compositions of the submarine turbiditic sands here are investigated in terms of bulk and heavy mineral modal compositions to identify their provenance and dispersal mechanisms, as they may reflect changes in regional tectonics during the past ca. 1.5 Myrs. The results show a marked change in the detrital signature and heavy mineral composition in the forearc and slope basin facies around 1 Ma. This sudden change is interpreted to reflect a major change in the sand provenance, rather than heavy mineral dissolution and/or diagenetic effects, in response to changing tectonics and sedimentation patterns. In the trench-slope basin, the sands older than 1 Ma were probably eroded from the exposed Cretaceous-Tertiary accretionary complex of the Shimanto Belt and transported via the former course of the Tenryu submarine canyon system, which today enters the Nankai Trough northeast of the study area. In contrast, the high abundance of volcanic lithics and volcanic heavy mineral suites of the sands younger than 1 Ma points to a strong volcanic component of sediment derived from the Izu-Honshu collision zones and probably funnelled to this site through the Suruga Canyon. However, sands in the forearc basin show persistent presence of blue sodic amphiboles across the 1 Ma boundary, indicating continuous flux of sediments from the Kumano/Kinokawa River. This implies that the sands in the older turbidites were transported by transverse flow down the slope. The slope basin facies then switched to reflect longitudinal flow around 1 Ma, when the turbiditic sand tapped a volcanic provenance in the Izu-Honshu collision zone, while the sediments transported transversely became confined in the Kumano Basin. Therefore, the change in the depositional systems around 1 Ma is a manifestation of the decoupling of the sediment routing pattern from transverse to long-distance axial flow in response to forearc high uplift along the megasplay fault. Copyright 2014 Springer-Verlag Berlin Heidelberg
Year of Publication: 2014
Research Program: IODP Integrated Ocean Drilling Program
Key Words: 06 Petrology, Sedimentary; 24 Surficial Geology, Quaternary Geology; Accretionary wedges; Basins; Cenozoic; Clastic rocks; Clastic sediments; Continental margin sedimentation; Currents; Decollement; Expedition 315; Expedition 316; Expedition 333; Facies; Fore-arc basins; Heavy minerals; IODP Site C0002; IODP Site C0006; IODP Site C0018; Igneous rocks; Integrated Ocean Drilling Program; Kumano Basin; Marine transport; Mineral composition; Modal analysis; NanTroSEIZE; Nankai Trough; Nesosilicates; North Pacific; Northwest Pacific; Ocean floors; Orthosilicates; Oxides; Pacific Ocean; Provenance; Quaternary; Ring silicates; Rutile; Sand; Sandstone; Sediment transport; Sedimentary rocks; Sedimentation; Sediments; Silicates; Submarine canyons; Suruga Canyon; Tectonics; Tourmaline group; Transport; Trenches; Turbidity currents; Volcanic rocks; West Pacific; Zircon; Zircon group
Coordinates: N331800 N331801 E1363801 E1363800
N330925 N330925 E1364053 E1364053
N330100 N330200 E1364800 E1364800
Record ID: 2014046901
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data supplied by Springer Verlag, Berlin, Federal Republic of Germany