Geochemistry of basement rocks of incoming plate (Cocos Ridge) from Sites U1381 and 1414, IODP Expeditions 334 and 344

Author(s): Yan Quanshu; Shi Xuefa
Author Affiliation(s): Primary:
State Oceanic Administration, First Institute of Oceanography, Qingdao, China
Volume Title: AGU 2015 fall meeting
Source: American Geophysical Union Fall Meeting, Vol.2015; American Geophysical Union 2015 fall meeting, San Francisco, CA, Dec. 14-18, 2015. Publisher: American Geophysical Union, Washington, DC, United States
Note: In English
Summary: The drilling sites of IODP 334 and 344 lie in the being subducted part of Cocos Ridge, offshore Costa Rica. Some seamount clusters distributed in the northwest side of the sites. Most scientists accepted that the Cocos ridge is intimately related to the activity of Galapagos plume (e.g., Hoernle et al., 2000, 2004, 2008). In this study we have selected some basaltic samples from U1381A, U1381C and U1414A (IODP 334 and 344) (Harris et al., 2015a, b) to carry out petrogenetic study. Major element compositions show that these basaltic rocks belong to sub-alkaline rocks, which is consistent with previous study on basalts from northern side of Cocos ridge. The characteristics of trace element composition are similar to that of EMORB, and the compositional differences in trace elements among samples reflect the influence of fractional crystallization. Sr-Nd-Pb isotopic compositions of these basaltic rocks show that there exist mantle heterogeneity beneath the Cocos ridge, and they may be the product of mixing between DMM/GSC and EMII. The new data show more enriched source feature than those from Galapagos hotspot (and its tracks) in previous study (Hoernle et al., 2000, 2004), and slightly more enriched than those Miocene to Pliocene arc volcanics from Central America (Gazel et al., 2009). Partial melting model show that the parental basalts for these basaltic rocks may be produced by 13 to 28% partial melting of garnet pyroxenite.
Year of Publication: 2015
Research Program: IODP Integrated Ocean Drilling Program
Key Words: 07 Marine Geology and Oceanography; Chemical composition; Cocos Ridge; Cores; Costa Rica Seismogenesis Project; East Pacific; Expedition 334; Expedition 344; Geochemistry; IODP Site U1381; IODP Site U1414; Integrated Ocean Drilling Program; Marine sediments; North Pacific; Northeast Pacific; Pacific Ocean; Sediments
Coordinates: N082543 N082543 W0840928 W0840929
N083014 N083014 W0841332 W0841332
Record ID: 2016101048
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