A multiple cave deposit assessment of suitability of speleothem isotopes for reconstructing palaeo-vegetation and palaeo- temperature ZHENG-HUA LI* † , STEVEN G. DRIESE ‡ and HAI CHENG §¶ *NASA Marshall Space Flight Center, 320 Sparkman Drive, NSSTC 2069, Huntsville, AL 35805, USA (E-mail: zheng-hua.li@nasa.gov) †Center for Space Plasma & Aeronomic Research, 320 Sparkman Drive, NSSTC 2017, Huntsville, AL 35899, USA ‡Department of Geology, Baylor University, One Bear Place #97354, Waco, TX 76798-7354, USA §Institute of Global Environmental Change, Xi’an Jiaotong University, Xi’an 710049, China ¶Department of Geological Sciences, University of Minnesota, 310 Pillsbury Dr. SE, Minneapolis, MN 55455, USA Associate Editor – Adrian Immenhauser ABSTRACT The suitability of speleothems for interpreting palaeoclimate is typically determined by using either the Hendy Test, overlapping analysis or long- term cave environment monitoring. However, in many cases, these methods are not applicable, because a speleothem lacks clearly traceable layers for the Hendy Test, it is difficult to obtain an overlapping speleothem nearby, or long-term cave monitoring is impractical. The authors propose a multiple cave deposit approach to assess the suitability of speleothems for palaeocli- mate study. Speleothems collected from two sites within Raccoon Mountain Cave, Tennessee (USA) exhibit remarkable spatial variation (δ 13 C: 103& to 22&) over a relatively short distance (ca 260 m). Drip water δ 18 O values exhibit a seasonal precipitation signal at Site 1 and an annual signal at Site 2. Combining field observations, water isotope analysis and trace-element data, the authors propose that the speleothem formation at Site 1 and Site 2 tapped distinct sources of CO 2 : (i) CO 2 derived from overlying soils for Site 1; and (ii) limestone dissolved inorganic carbon induced by ground water dissolution for Site 2. Using fresh cave deposits (modern speleothem) δ 13 C (100% C3 vegetation) as an analogue, a simple model was developed to esti- mate land surface vegetation for speleothems. The speleothem formation temperature estimated using fresh cave deposit δ 18 O values generally reflects the mean annual temperature in this region. This study indicates that spatial variations in carbon isotopes could be caused by different carbon sources dominating in different parts of the cave, which should be taken into consid- eration by researchers when using speleothem δ 13 C values to reconstruct temporal palaeo-vegetation changes. This study demonstrates a practical sampling strategy for verifying suitability of speleothems for palaeo-vegeta- tion and palaeo-temperature reconstructions by analysing multiple cave deposits, especially for cases in which the Hendy Test, parallel sampling and long-term monitoring of cave environment are not feasible. Keywords Cave deposit, southern Appalachians, speleothem, stable iso- tope, vegetation. © 2013 The Authors. Sedimentology © 2013 International Association of Sedimentologists 749 Sedimentology (2014)61, 749–766 doi: 10.1111/sed.12078