Betzler, C., Eberli, G.P., Alvarez Zarikian, C.A., and the Expedition 359 Scientists Proceedings of the International Ocean Discovery Program Volume 359 publications.iodp.org doi:10.14379/iodp.proc.359.104.2017 Site U1466 1 C. Betzler, G.P. Eberli, C.A. Alvarez Zarikian, M. Alonso-García, O.M. Bialik, C.L. Blättler, J.A. Guo, S. Haffen, S. Horozal, M. Inoue, L. Jovane, D. Kroon, L. Lanci, J.C. Laya, A. Ling Hui Mee, T. Lüdmann, M. Nakakuni, B.N. Nath, K. Niino, L.M. Petruny, S.D. Pratiwi, J.J.G. Reijmer, J. Reolid, A.L. Slagle, C.R. Sloss, X. Su, P.K. Swart, J.D. Wright, Z. Yao, and J.R. Young 2 Keywords: International Ocean Discovery Program, IODP, JOIDES Resolution, Expedition 359, Site U1466, Maldives, Kardiva Channel, Goidhoo atoll, Indian Ocean paleoceanography, Oligocene, Miocene, Pliocene, Pleistocene, carbonate platform, carbonate platform drowning, celestine, dolomite, drift deposits, large benthic foraminifers, monsoon, sea level, sequence stratigraphy 1 Betzler, C., Eberli, G.P., Alvarez Zarikian, C.A., Alonso-García, M., Bialik, O.M., Blättler, C.L., Guo, J.A., Haffen, S., Horozal, S., Inoue, M., Jovane, L., Kroon, D., Lanci, L., Laya, J.C., Ling Hui Mee, A., Lüdmann, T., Nakakuni, M., Nath, B.N., Niino, K., Petruny, L.M., Pratiwi, S.D., Reijmer, J.J.G., Reolid, J., Slagle, A.L., Sloss, C.R., Su, X., Swart, P.K., Wright, J.D., Yao, Z., and Young, J.R., 2017. Site U1466. In Betzler, C., Eberli, G.P., Alvarez Zarikian, C.A., and the Expedition 359 Scientists, Maldives Monsoon and Sea Level. Proceedings of the International Ocean Dis- covery Program, 359: College Station, TX (International Ocean Discovery Program). http://dx.doi.org/10.14379/iodp.proc.359.104.2017 2 Expedition 359 Scientists’ addresses. MS 359-104: Published 4 May 2017 This work is distributed under the Creative Commons Attribution 4.0 International (CC BY 4.0) license. Contents 1 Background and objectives 2 Operations 5 Lithostratigraphy 14 Biostratigraphy 22 Geochemistry 26 Paleomagnetism 30 Physical properties 34 Downhole measurements 39 Seismic stratigraphy 41 References Background and objectives Site U1466 (proposed MAL-02) is positioned 1880 m east of Site U1465 at 4°55.9880′N, 73°1.6894′E, at about the same water depth (518 m), but it is situated above completely different strata (Figures F1, F2). The site is in front of the last prograding clinoform of the drowned carbonate platform targeted at Site U1465. In this basinal position, a thick prograding drift succession first overlays the bottomsets and foresets of the prograding platform and finally buries the platform (Figure F55). The main objective of Site U1466 was to retrieve and date the first drift sequence and the subsequent changes in current evolution that are likely related to the evolution of the Indian monsoon (Kroon et al., 1991). Thus, the site is located just east of the first onlap of the drift onto the slope of the buried platform. The drift sequence is partly eroded on top as a moat de- velops along the platform to the west (Lüdman et al., 2013). A con- densed section covers the erosional unconformity overlain by a horizontally layered drift package that is wavy at the seafloor. Hole U1466A was intended to retrieve the first drift sequence, the con- densed section, and the overlying drift package. A second major objective at this site was to establish ages for sea level changes interpreted as being responsible for the pulses of plat- form progradation that produce platform sequences (Betzler et al., 2013b). This site penetrated the foresets and bottomsets of the pro- grading platform, so individual platform sequences can be dated. Dating platform sequences within shallow-water deposits or even the platform margin is inherently difficult because age-diagnostic planktonic foraminifers and calcareous nannofossils are generally absent. Dating carbonate sequences in the basinal portion of the se- quence is a common approach to overcome the problem. Although sequence boundaries are determined by onlap unconformities along the platform margin, seismic reflections marking sequence bound- aries can be traced into the basin. Because of the chronostrati- graphic nature of the seismic reflections, ages can be determined in this basinal position by dating sediments above and below the hori- zon that generates the sequence boundary reflection (Eberli et al., 2002). Thus, ages of early and middle Miocene sea level changes in the Indian Ocean will be retrieved. Together with data sets from the Bahamas (Ocean Drilling Program [ODP] Leg 166) and offshore eastern Australia (ODP Legs 133 and 194), these ages will allow sci- entists to test the global synchroneity of Neogene sea level changes. Site U1466 cores also address another major objective of Expe- dition 359. The periplatform sediments deposited at this site offer the opportunity to retrieve a complete δ 13 C record through the lower and middle Miocene that together with other Expedition 359 sites will provide another data set of the carbon isotopic record needed to calibrate the periplatform platform margin record against the pelagic record. Open oceanic pelagic records offer the best data for reconstructing the global carbon cycle (Shackleton, 1985), but for Earth’s pre-Mesozoic history, only the record of platform-de- rived sediments is preserved (Veizer et al., 1999). Because peri- platform and pelagic records can differ significantly, calibration is important for a meaningful interpretation of the δ 13 C record in Earth’s ancient history (Swart and Eberli, 2005; Swart, 2008). The specific objectives at Site U1466 were as follows: (1) con- strain the timing of onset of drift deposition, the condensed section that indicates a current change, and platform sequence boundaries; (2) reconstruct and date bank to drift turnover; (3) provide detailed reconstruction of the predrowning, drowning, and postdrowning evolution of the carbonate bank by linking the seismic stratigraphic record to the sedimentary record; and (4) establish a carbon isotope record from the periplatform sediments.