DEVELOPING QUATERNARY GLACIAL CHRONOLOGIES FOR THE HIMALAYAN-TIBETAN OROGEN TO HELP DEFINE THE NATURE OF PALEOCLIMATE CHANGE FOR HIGH-LATITUDES IN SUBTROPICAL REGIONS

Much effort has been made in recent years to define the timing and extent of Quaternary glaciation throughout the Himalayan-Tibetan (H-T) orogen. These studies are challenging because of the logistical and political inaccessibility of the region, and the inherent problems associated with the application of numerical dating techniques. Nevertheless, the studies are providing abundant evidence for significant glacial advances throughout the last few glacial cycles and are beginning to accurately define the extent and timing of glaciation in selected regions. In particular, the studies are showing that H-T glaciers during the last glacial cycle reached their maximum extent early in the cycle and that true LGM glacier advances were significantly less extensive. However, along the Greater Himalaya, there is increasing evidence to suggest that glaciation was more extensive later in the last glacial cycle, but this has yet to be fully assessed. In addition, the new studies are showing that throughout most H-T regions, significant glacier advances occurred during the Lateglacial and early Holocene, with minor advances in some regions during the mid-Holocene. The still relatively poor chronological control in the H-T orogen, however, makes it difficult to construct correlations across the region, and with regions elsewhere in the world. This in turn makes it hard to assess the relative importance of the different climatic mechanisms that force glaciation across the H-T orogen, and to quantify paleoclimate change in this high altitude subtropical region. The Lateglacial and Holocene glacial records, however, are particularly well preserved in several H-T regions. Glacial successions such as these have the greatest potential to be examined in much detail using newly developing numerical dating, and geomorphic and sedimentologic methods to derive high-resolution records of glaciation that will help in paleoclimatic reconstruction for high altitude subtropical regions.