SUMMARY

Characteristics of formation and distribution of lava caves in the Central Highlands and
Southeast (Vietnam) in the light perspective of geomorphic studies

Đặng Văn Bào, Ngô Văn Liêm, Trần Văn Trị

The aim of this paper is clarifying the role and the geomorphological significance of the formations related to the volcanic cave formation and development process in the Central Highlands and Southeast regions of Vietnam. Accordingly, the topography of volcanic caves distribution area in Krông Nô (Đắk Nông) and Tân Phú - Định Quán (Đồng Nai) are characterized with the form of the primary basalt lava and they are still well preserved today. Especially, on the terrain surface, it is possible to observe "inert rock desert landscape" with relatively fresh basalt blocks, poor weathering level, thin soil layer and sparse vegetation. Based on the topography, lithology and weathering crust, characteristics of Chư B'luk basalt formations allow to be related to the Late Pleistocene (possibly to Holocene) Phước Tân formation, with the established standard profile in Đồng Nai province. The primary lava caves in the Central Highlands and Southeast regions are observed in areas with the distribution of the youngest basalt formation (Phước Tân formation) and near the craters that are still shown clearly on the topography. The lava caves’ basalt was formed in the recent stages, following to the lava flows, they blocked and filled ancient valleys and created lakes and swamps in the upstream. The clarification of the formation characteristic, development and distribution rules of the lava cave systems in the Central Highlands and the Southeast of Vietnam in relation to the youngest volcanic activity have many scientific and practical meanings in conservation and rational use of resources in the region.