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Input Site U14141

R.N. Harris, A. Sakaguchi, K. Petronotis, A.T. Baxter, R. Berg, A. Burkett, D. Charpentier, J. Choi, P. Diz Ferreiro, M. Hamahashi, Y. Hashimoto, K. Heydolph, L. Jovane, M. Kastner, W. Kurz, S.O. Kutterolf, Y. Li, A. Malinverno, K.M. Martin, C. Millan, D.B. Nascimento, S. Saito, M.I. Sandoval Gutierrez, E.J. Screaton, C.E. Smith-Duque, E.A. Solomon, S.M. Straub, W. Tanikawa, M.E. Torres, H. Uchimura, P. Vannucchi, Y. Yamamoto, Q. Yan, and X. Zhao2

Background and objectives

The primary objective of Integrated Ocean Drilling Program Expedition 344 was to sample and quantify the material comprising the seismogenic zone of an erosive subduction margin. Fundamental to this objective is an understanding of the nature of the sediment and oceanic crust entering the seismogenic zone, the hydrologic system, and the thermal state of the igneous oceanic crust. Site U1414 (proposed Site CRIS-19A) serves as a secondary reference site on the flank of the subducting aseismic Cocos Ridge.

Site U1414 is located within the 3-D seismic volume along Line 2497 and crossing Line 2562 (Fig. F1) and is ~1 km seaward of the deformation front offshore the Osa Peninsula and Caño Island (Fig. F2). This site was chosen for multiple reasons. First, a clear seismic record of the plate stratigraphy is present at this site. The seismic section shows a 400 m thick sediment section resting on reflective basement interpreted as Cocos Ridge igneous crust. Second, the sedimentary section is thought to be composed of pelagic and hemipelagic sediments that may record the interval missing at Site U1381. Third, a reflector of interest exists about two-thirds of the way through the sediment column. Finally, this site presents an opportunity to collect igneous basement.

Primary science goals at Site U1414 included (1) documenting the presence or absence of the hiatus observed at Site U1381, (2) documenting the presence or absence of tephras during the 9–11 m.y. hiatus documented at Site U1381, and (3) documenting the alteration state of basement. Finally, because of oblique convergence of subduction at the Middle America Trench, sediments at Site U1414 likely correspond to the sediments now being subducted under seismic Line BGR99-7. Documenting the physical state and water content of these sediments was also important.

Sediment thickness along the inline seismic transect (southwest–northeast) is variable and reflects the relief of the Cocos Ridge basement.

1 Harris, R.N., Sakaguchi, A., Petronotis, K., Baxter, A.T., Berg, R., Burkett, A., Charpentier, D., Choi, J., Diz Ferreiro, P., Hamahashi, M., Hashimoto, Y., Heydolph, K., Jovane, L., Kastner, M., Kurz, W., Kutterolf, S.O., Li, Y., Malinverno, A., Martin, K.M., Millan, C., Nascimento, D.B., Saito, S., Sandoval Gutierrez, M.I., Screaton, E.J., Smith-Duque, C.E., Solomon, E.A., Straub, S.M., Tanikawa, W., Torres, M.E., Uchimura, H., Vannucchi, P., Yamamoto, Y., Yan, Q., and Zhao, X., 2013. Input Site U1414. In Harris, R.N., Sakaguchi, A., Petronotis, K., and the Expedition 344 Scientists, Proc IODP, 344: College Station, TX (Integrated Ocean Drilling Program). doi:10.2204/​iodp.proc.344.104.2013

2Expedition 344 Scientists’ addresses.

Publication: 11 December 2013
MS 344-104