Detrital sediment supply in the southern Okinawa Trough and its relation to sea-level and Kuroshio dynamics during the late Quaternary
Resource
Marine Geology 255 (1-2): 83-95
Journal
Marine Geology
Journal Volume
255
Journal Issue
1-2
Pages
83-95
Date Issued
2008
Author(s)
Diekmann, Bernhard
Hofmann, Jana
Henrich, R?diger
F?tterer, Dieter K.
R?hl, Ursula
Abstract
During Leg 195 of the Ocean Drilling Program, Site 1202 was drilled in the subtropical northwestern Pacific Ocean beneath the Kuroshio ("Black Current") between northern Taiwan and the Ryukyu Island Arc on the northern flank of the I-Lan Ridge at 1274 m water depth. The upper 110 m of the Site 1202 section, composed of dark grey calcareous silty clay, provide an expanded record of environmental changes during the last 28 kyr. The sediments were deposited at high sedimentation rates between 3.0 and 5.0 m/kyr and peak values of 9.0 m/kyr between 15.1 and 11.2 ka BP. Variations in the modes and sources of detrital sediment input, as inferred from sediment granulometry, mineralogy, and elemental XRF-scanner data, reflect changes in environmental boundary conditions related to sea-level changes, Kuroshio variability, and the climate-driven modes of fluvial runoff. The provenance data point to increased sediment supply from northwestern Taiwan between 28 and 19.5 ka BP and from East China sources between 19.5 and 11.2 ka BP. The change in provenance at 19.5 ka BP reflects increased fluvial runoff from the Yangtze River and strong sediment reworking from the East China Sea shelf in the course of increased humidity and postglacial sea-level rise, particularly after 15.1 ka BP. The Holocene was dominated by sediments that originated from rivers in northeastern Taiwan. For the pre-Holocene period prior to 11.2 ka BP, low portions of sortable silt (63-10 μm) show that the Kuroshio did not enter the Okinawa Trough, because of low sea-level. In turn, high proportions of sortable silt and sediment provenance from northeastern Taiwan point to strong ocean circulation under the direct and persistent influence of the Kuroshio during the Holocene. The reentrance of the Kuroshio to the Okinawa Trough was heralded by two pulses in relative current strengthening at 11.2 and 9.5 ka BP, as documented by stepwise increases in sortable silt in the lower Holocene section. From a global perspective, environmental changes in the southern Okinawa Trough show affinities to climate change in the western Pacific warm pool with little influence of climate teleconnections from the North Atlantic realm, otherwise seen in many other marine and terrestrial palaeoclimate records from southeastern Asia. © 2008 Elsevier B.V. All rights reserved.
Subjects
clay-minerals; granulometry; ODP Site 1202; Pacific Ocean; sediment provenance
Other Subjects
Black current; Boundary conditioning; Climate teleconnections; Data points; East China Sea; Environmental changes; granulometry; Holocene; Kuroshio; Late-Quaternary; North Atlantic; Northeastern Taiwan; Northern Taiwan; Ocean circulations; Ocean drilling program; ODP Site 1202; Okinawa Trough; Pacific Ocean; Palaeoclimate; Peak values; Scanner data; Sea-level changes; Sea-level rise; sediment provenance; Sediment supply; Sedimentation rates; Silty-clay; Water depths; Western Pacific Warm Pool; Yangtze River; Backpropagation; Boundary conditions; Boundary value problems; Clay minerals; Climate change; Crystallography; Lithology; Mineralogy; Minerals; Oceanography; Offshore oil wells; Ore deposit geology; Runoff; Sedimentation; Sedimentology; Sediments; Silt; Sulfate minerals; Underwater mineralogy; Ocean currents; detrital deposit; environmental change; granulometry; Holocene; Ocean Drilling Program; paleoclimate; Quaternary; sea level; sedimentation; subtropical region; trough; Asia; China; East China Sea; Eurasia; Far East; Japan; Kuroshio Current; Okinawa Trough; Pacific Ocean; Ryukyu Islands; Taiwan; Yangtze River
Type
journal article
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