Three ice cores were drilled to bedrock in 1987 at the summit of the Dunde ice cap (38°06'N, 96°24'E, 5325m.) 
on the north-central Qinghai-Tibetan Plateau of China. Core D-1 (139.8m.) was cut into 3,585 samples 
and analyzed on-site for microparticles and oxygen isotopes. The upper 56m of core D-3 (138.4) was melted and bottled. 
The lower 83m. of core D-3 was kept frozen.

References:
Thompson, L.G., E. Mosley-Thompson, M.E. Davis, J.F. Bolzan, T. Yao, N. Gundestrup, X. Wu, L. Klein, and Z. Xie. 1989. 
100,000 year climate record from Qinghai-Tibetan Plateau ice cores. 
Science, 246(4929), 474-477.

Thompson, L.G., E. Mosley-Thompson, M.E. Davis, P.-N. Lin, K. Henderson, and T.A. Mashiotta. 2003. 
Tropical glacier and ice core evidence of climate change on annual to millennial time scales. 
Climatic Change, 59, 137-155.

Thompson, L.G., E. Mosley-Thompson, H. Brecher, M. Davis, B. Leon, D. Les, P.-N. Lin, T. Mashiotta, and K. Mountain. 2006. 
Abrupt tropical climate change: Past and present. 
Proceedings of the National Academy of Sciences, Vol. 103, No. 28, pp. 10536-10543, 11 July, 2006. DOI: 10.1073/pnas.0603900103