Dry climate near the Western Pacific Warm Pool: Pleistocene caliches of the Nansha Islands, South China Sea Shou-Yeh Gong a, * , Horng-Sheng Mii b , Kuo-Yen Wei c , Chorng-Sherng Horng d , Chen-Feng You e , Fu-Wen Huang f , Wen-Rong Chi f , Tzen-Fu Yui d , Pei-Keng Torng f , Shieu-Tsann Huang f , Shih-Wei Wang a , Jong-Chang Wu f , Kenn-Ming Yang f a Department of Geology, National Museum of Natural Science, Taichung, Taiwan b Department of Earth Sciences, National Taiwan Normal University, Taipei, Taiwan c Department of Geosciences, National Taiwan University, Taipei, Taiwan d Institute of Earth Sciences, Academia Sinica, Taipei, Taiwan e Department of Earth Sciences, The National Cheng-Kung University, Tainan, Taiwan f Exploration and Development Research Institute, Chinese Petroleum Corporate, Miaoli, Taiwan Received 8 September 2004; received in revised form 12 May 2005; accepted 23 May 2005 Abstract The Nansha (Spratly) Islands are located in the middle of the South China Sea (at about 108N) near the northwestern margin of the Western Pacific Warm Pool (WPWP). A borehole was drilled at an atoll at Nansha, and cores were taken. The upper 165.4 m of the borehole consists entirely of limestone of reef facies and lagoon facies, which had been influenced by extensive meteoric diagenesis. Petrographic and geochemical studies have identified at least four subaerial exposure surfaces (SES) in the Pleistocene carbonate sequence. These SES are thought to have resulted from global sea-level changes and characterized by caliche formation. When developed in limestone, caliches typically form in areas where annual precipitation ranges from 500 mm up to about 1200 mm, compared with 1800–2200 mm of annual rainfall of the present-day Nansha Islands. The Nansha caliche therefore indicates the existence of several dry climate episodes during Pleistocene sea-level lowstands. Lower rainfall and higher evaporation during such dry conditions may explain the higher sea-surface salinities reported elsewhere in the South China Sea. The Nansha caliche may also indicate reduced extent of the WPWP and southerly shift of the Intertropical Convergence Zone during major sea-level lowstands. D 2005 Elsevier B.V. All rights reserved. Keywords: Caliche; Palaeoclimate; Sea-level changes; Nansha Islands; South China Sea 1. Introduction Scientists are divided as to the climates of western Pacific tropical seas during glacial periods. Determin- 0031-0182/$ - see front matter D 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.palaeo.2005.05.012 * Corresponding author. Fax: +886 4 23222653. E-mail address: gng@mail.nmns.edu.tw (S.-Y. Gong). Palaeogeography, Palaeoclimatology, Palaeoecology 226 (2005) 205– 213 www.elsevier.com/locate/palaeo