Early sedimentation and deformation in the Kumano forearc basin linked with Nankai accretionary prism evolution, southwest Japan

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doi: 10.1002/2014GC005643
Author(s): Ramirez, Sebastian G.; Gulick, Sean P. S.; Hayman, Nicholas W.
Author Affiliation(s): Primary:
University of Texas at Austin, Jackson School of Geosciences, Austin, TX, United States
Volume Title: Geochemistry, Geophysics, Geosystems - G<sup>3</sup>
Source: Geochemistry, Geophysics, Geosystems - G>3`, 16(5), p.1616-1633. Publisher: American Geophysical Union and The Geochemical Society, United States. ISSN: 1525-2027
Note: In English. 52 refs.; illus., incl. sketch map
Summary: Early forearc basin sedimentation and subsidence appear to be linked with convergent margin evolution, yet they do not follow predictable spatiotemporal patterns. In the Kumano basin of southwest Japan, 3-D seismic mapping of major unconformities, combined with biostratigraphic age constraints from two Integrated Ocean Drilling Program (IODP) drill sites illustrates the development of several tectonostratigraphic packages during early evolution and initial creation of accommodation space in the forearc basin. Between ∼3.8 Ma and ∼2.06 Ma, a series of slope basins developed between thrust-anticlines oriented along a plate convergence-perpendicular axis. A thin and sheet-like interval, likely slope-cover, unconformably overlies the slope basin sediments. Deposition of this interval at IODP Site C0009 lasted from ∼2.06 Ma until between ∼1.24 Ma and ∼1.34 Ma and was partly coeval with the early upper Kumano basin sedimentary packages. Landward, postdating the slope-cover sediments, a third sedimentary package was deposited before ∼0.9 Ma. This section correlates with an interval rich in terrigenous material (e.g., woody debris), indicating a possible distinct source or sediment routing system. Our work supports the idea that early forearc basin sediments may be deposited in an actively deforming outer wedge environment and that the outer-to-inner wedge transition of the lower forearc basin is likely a multistage process. The unsteady spatiotemporal nature of inner-outer wedge coupling may lead to erratic stratigraphic patterns, such as have been observed in forearc basins worldwide. Abstract Copyright (2015), American Geophysical Union. All Rights Reserved.
Year of Publication: 2015
Research Program: IODP Integrated Ocean Drilling Program
Key Words: 07 Marine Geology and Oceanography; 16 Structural Geology; Accretionary wedges; Active margins; Asia; Basins; Deformation; Expedition 319; Far East; Fore-arc basins; IODP Site C0002; IODP Site C0009; Integrated Ocean Drilling Program; Japan; Kumano Basin; Marine sedimentation; NanTroSEIZE; Nankai Trough; North Pacific; Northwest Pacific; Pacific Ocean; Plate convergence; Sedimentary basins; Sedimentation; Subsidence; Tectonic wedges; Tectonics; Tectonostratigraphic units; West Pacific
Coordinates: N325000 N333000 E1370000 E1362000
Record ID: 2017009326
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