Orbital scale oxygen isotope stratigraphy at Sites U1417 and U1418 in the Gulf of Alaska (IODP Exp. 341)
Abstract
Understanding the linkage between erosional effluxes from orogenic belts and glaciations is important for Pleistocene landscape studies. Although an increase of erosional efflux into the Gulf of Alaska (GoA) corresponding with longer duration of glacial periods after the mid-Pleistocene transition (MPT: 1.2-0.7 Ma) has been observed based on shipboard age models from IODP Expedition 341 drilling sites, its response at orbital scales (Glacial Interglacial cycle: G-IG cycle) is still not clear. Here we present orbital scale age models of two sites (U1417 and U1418) of IODP Expedition 341, testing the aforementioned hypothesis at the G-IG cycle level. Common presence of planktic foraminifers throughout U1418 and above 147 m CCSF-B in U1417 allow us to achieve an orbital scale age model back to 1.2 Ma. Approximately seven times higher sedimentation rate (SR) at margin proximal site U1418 (average SR: 82 cm / kyr) compared to that at U1417 (average SR: 11 cm / kyr) suggests large sediment discharge to the Surveyor Fan from the continental margin of Alaska. Temporal variation of SR at U1418 in the Surveyor Fan showed unique trends within three time windows: (1) 1.1-1.0 Ma: high average SR (120 cm/kyr) with SR peaks during IG maxima; (2) 1.0-0.6 Ma: low average SR (50 cm/kyr) with SR peaks during IG maxima; and (3) after 0.6 Ma: high average SR (90 cm/kyr) with SR peaks at the transition from IG to G. At pelagic Site U1417, SR peaks mostly appeared at IG maxima and a subtle average SR increase occurred at 0.6 Ma. Since 100 kyr cyclicity of G-IG cycle became relevant after 0.6Ma, our finding supports the idea of previous studies that there was an increase in sediment flux during glacial periods of longer duration.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2016
- Bibcode:
- 2016AGUFM.T44B..08A
- Keywords:
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- 4207 Arctic and Antarctic oceanography;
- OCEANOGRAPHY: GENERALDE: 8158 Plate motions: present and recent;
- TECTONOPHYSICSDE: 8175 Tectonics and landscape evolution;
- TECTONOPHYSICSDE: 8177 Tectonics and climatic interactions;
- TECTONOPHYSICS