Berliner Höhlenkundliche Berichte, Volume 22: Northern Vietnam 1993-2006

This report has been compiled from the results of eight Belgian–Vietnamese speleological expeditions to the NW of Vietnam between 1993 and 2006. Karst and caves of five provinces were studied with the provinces of Son La and Lai Chau having been subject of the most detailed investigations, which have led to a long-term development project in both provinces. During the expeditions 270 caves were explored. In total over 92 km of cave passages were surveyed. Amongst them is Cong Nuoc Cave in the Tam Duong area at a depth of -600 m, currently the deepest cave on the mainland of Southeast Asia. The longest cave surveyed so far is the 2920 m long Noong Khat. A total of 24 caves at a length of over 1 km were found, and 265 caves were mapped in the provinces described in this publication. Two other caves were also added to the list of investigated caves: Xa Xa Pin 2 in the Dong Van area, surveyed by a previous Italian expedition, as well as Cau Cuoi in the Yen Bai province. On the way between Son La and Hanoi two more caves (Co Du and Hang Nghiem) were explored in the Moc Chau area in 1997. In 2001 a further cave (Nam Phe 1) was surveyed in the Nam Phe area of the Tam Duong region, which is located north of the areas that were studied in the Lai Chau province. This brings the total of described caves to the number of 270.

Abstract / Zusammenfassung / Résumé / Tóm tat     5

1     Acknowledgements / Team Meübers/ Sponsors     7
2     Introduction     9
3     General overview     10
3.1     Geological observations     10
3.2     Son La province     13
3.2.1     Location     13
3.2.2     Hydrometeorology     13
3.2.3     Tectonics     14
3.2.4     Stratigraphy     17
3.3     Lai Chau province     18
3.4     Hoa Binh province     18
3.5     Bac Kan province     20
3.6     Ha Giang province     22
4     Caves explored during the 1993 — 2006 expeditions     23
4.1     General remarks     23
4.2     Son La and Lai Chau provinces     24
4.3     Hoa Binh, Bac Kan and Ha Giang provinces     146
4.4     Other caves investigated     197
4.5     Preliminary speläogenetic model (by Christophe Deblaere & David Lagrou)     200
5     Conclusions     202
6     Bibliography     202

Annex     
Caves explored during the BVKCA speleological projects 1993 – 2006 in North Vietnam     207