ABSTRACT
We use stable oxygen isotope variations in cave calcites [CaCO3 stalactites and stalagmites, collectively known as speleothems; see Yadava and Ramesh (1999) for the detailed methodology] to reconstruct past monsoon variations. Caves are among the longest-lived components of landscapes, surviving for millions of years. The most preferred archive for paleoclimatic reconstruction after tree rings and corals are speleothems. Stalagmite, a columnshaped speleothem forming on the cave oor, is like a stone tree growing for many thousands of years. Having the cover of overlying bedrock and soils, these have natural protection against erosion and weathering. Calcite stalagmites, stalactites, and owstones are useful for environmental reconstruction. For dating speleothems, both radiocarbon and U-Th methods are applied. However, these methods have certain limitations: for example, in any speleothem, the varying fraction of dead carbon derived from the bedrock may result in radiocarbon ages that may not show increasing age for older layers. Also, 14C method cannot be applied beyond approximately 40 to 50 ka when radiocarbon detection is not possible. High ne-dust (detrital) content in the seepage water having dissolved ionic species may produce UTh ages with large uncertainty as well as age reversals. Thus far, ve Indian caves have been explored for generating terrestrial monsoon history of the Indian subcontinent. Here, we use the data from one such cave to study the application of wavelets.
