Kurzfassung: The Ma river delta located in the North Central of VietNam is the third largest ones in Vietnam following the Mekong Delta and the Red River Delta. However, there are not many researches on sedimentary. This study aims to determine the Characteristics of the Holocene sedimentary facies in coastal plain of the Song Ma Delta based on observation of sedimentary structure and analysis of grain size, diatom, flora, pollen and 14C dating collected for the drill core (LKTH2 borehole) from the coastal plain of the Song Ma river delta. Research results identify 08 facies consisting 02 facies of transgression period and 06 facies of regression period. During transgression period, 02 facies of tidal flat clayish silt and bay silty clay facies were formed. Of which, tidal flat clayish silt face was formed in 7,883 ± 43 14C yr BP. After the maximum flooding of the sea, the delta was initiated and 06 facies were formed during the regression period i.e. prodelta silty clay, delta front clayish silt, tidal flat sandy - silty clay, sand ridge, lagoonal sandy silty clay, and flood plain silty clay facies. The tidal flat sandy - silty clay facies occurred in 6.951± 38 14Cyr BP caused by sea level fall and the coastline was identified around the LKTH2 bore hole at that time. Integration of sedimentary facies of the sand ridge and lagoonal sandy silty clay facies shows that the Song Ma Delta was dominated by wave process during its evolution.

Kurzfassung: The paper presents the initial results of the study of volcanic cave system and its typical formations in Krongno Volcano Geopark (KVG), Dak Nong, Vietnam. The volcanic caves have been discovered since 2007, under UNESCO sponsored the scientific project, are seen as unique geological heritages. The collaborative surveys and studies between Vietnamese geologists and the members of the Non-Profit Organization, Vulcanospeleological Society of Japan have discovered and surveyed 45 caves, and detailed mapping 20 caves. Using a complex of adequate methods, especially Remote Sensing image interpretation method, Surveying and mapping lava cave method, K/Ar dating isotopic analytical method and Current methodology, the studies aim to affirm endogenous origin of the lava cave system, the formation mechanism, as well as the typical formations of the caves. Up to date, the lava caves and interior formation in lava caves in KVG have been examined and evaluated in term of geological nature and recognized as pillar geological heritages of the Geopark.References Allred K., AllredC., 1997. Development and morphology of Kazumura Cave, Hawaii. Journal of Cave and Karst Studies, 59(2), 67-80.Allred K., Allred C., 1997. Tubular lava stalactites and other related segregations. Journal of Cave and Karst Studies, 60(3), 131-140.Barnabás Korbély, 2014. Diverse volcanic features as dominant landscape elements and pillars of geotourism in the Bakony-Balaton Geopark, Hungary. Abstract Book Workshop “Geoparks in volcanic areas: sustainable development strategies”, October 29th to November 1st, 2014. Terceira and Graciosa Islands, Azores Global Geopark, 35-38.Bird Deanne K., et al., 2014. Southern Iceland: Volcanoes, Tourism and Volcanic Risk Reduction.In Volcanic Tourist Destinations. Springer, Editors: Erfurt-Cooper, Patricia (Ed.). ISBN: 978-3-642-16190-2, 35-46. Cooper Malcolm J.M., 2014. Volcanic National Parks in Japan.In Volcanic Tourist Destinations. Springer, Editors: Erfurt-Cooper, Patricia (Ed.). ISBN: 978-3-642-16190-2, 231-246.Dave Bunnell, 2014. The virtual lava cave Created: August 4, 2000.Last update: December 16, 2014. Reviewed by Kevin & Carlene Allred. Available at: 〈 http://www.goodearthgraphics.com/virtual_tube/virtube.html). Date accessed: 02 May 2018.Gadányi P., 2010. Formation, types and morphology of basalt lava caves. PhD. thesises. University of Pécs Faculty of Natural Sciences Doctoral School of Earth Sciences, Hungary, 1-19.Gaki-Papanastassiou, Kalliopi, et al., 2014. Volcano Tourism in Greece: Two Case Studies of Volcanic Islands.In Volcanic Tourist Destinations. Springer, Editors: Erfurt-Cooper, Patricia (Ed.). ISBN: 978-3-642-16190-2, 69-87.Honda T., Tachihara H., 2015. 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Kurzfassung: Ba River originates from the Ngoc Linh mountain ranges, NW of Kontum massif and flows into the East Sea from the Da Rang estuary. The Ba River basin (Da Rang river) is considered as the means of transport and storage of products from the Kontum massif resulted following weathering, erosion or deformation processes either by natural causes or the regional thermo-tectonic events. A total of 122 zircon grains separated from the Ba River basin sediments are selected for U-Pb isotopic age dating by LA-ICP-MS method. Among the 122 samples, 114 are concordant, forming 3 major age groups, including middle-Late Cretaceous (105–85 Ma), Middle Permian - Late Triassic (270–211 Ma), Late Ordovician - Early Silurian (455–424 Ma). A few samples show ages scattering from 1470 to 970 Ma (Mesoproterozoic), and one sample shows a value of 2383±24 Ma (Paleoproterozoic). The acquired U-Pb zircon ages may reflect 3 major thermo- tectonic stages in the formation and evolution of the Kontum Massif from the Early Paleoproterozoic till middle-Late Cretaceous, with the most significant time being Middle Permian (270 Ma)-Late Triassic (211 Ma) (97 over 122 samples, e.g., 79,5%), corresponding to the period of convergence, collision and orogeny of the Indosinian block.