Sedimentary petrology characteristics and their implications for provenance of Hoanh Bo Basin Neogene system in Quang Ninh province, north-eastern Vietnam

Abstract

Abstract:The Hoanh Bo Basin has developed over multiple periods since the Miocene period in association with the tectonic activity of the Chi Linh-Hon Gai and Trung Luong Faults. The basin is filled with Neogene continental sediments, comprising mainly polymictic conglomerates, sandstones, siltstones, claystones, and shales. Coarser-grained polymictic deposits predominate along the northern and western margins of the basin, whereas different types of siltstones, claystones, and sandstones occur in its centre, as well as along its southern and eastern parts, toward the Ha Long Bay. The conglomerates and sandstones are composed mainly of quartz and sedimentary rock fragments, and a small amount of mica. Cement is mainly built of iron-oxide, clay or carbonate mud. The source area for the Hoanh Bo Basin sediments was located in the close vicinity of the basin. It was built of strongly weathered rocks of the Hon Gai, Ha Coi, Cat Ba Formations.

Leaf fossils of Sabalites (Arecaceae) from the Oligocene of northern Vietnam and their paleoclimatic implications

“…1 ). Hoanh Bo Basin is a small strike-slip fault basin along the Red River Fault System ( Tha et al., 2017 ). The fossil site is located in the northern part of the basin ( Fig.…”

“…1 ). The Cenozoic sediments in the basin consist of the Dong Ho Formation, Tieu Giao Formation, and Quaternary deposits from the bottom to upper parts ( Petersen et al., 2005 ; Tha et al., 2017 ). The outcrop of the Dong Ho Formation is approximately 80 m thick ( Fig.…”

“…The outcrop of the Dong Ho Formation is approximately 80 m thick ( Fig. 2 ) and dominated by gray to black weakly or non-laminated to structureless organic-rich mudstones interbedded with thin layers of muddy sandstones, representing a low energy, long-lasting lacustrine environment ( Petersen et al., 2005 ; Tha et al., 2017 ). This formation yields numerous plant megafossils, spores and pollen ( Nhan and Danh, 1975 ; Trung et al., 1999a , b , 2000 ).…”

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Fig. 1 Geological map with the location of the fossil site (modified from Petersen et al., 2005 ; Tha et al., 2017 ). a, Location of the study area.

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The Hoanh Bo Trough‐a landward keyhole to the syn‐rift Late Eocene–Early Oligocene terrestrial succession of the northern Song Hong Basin (onshore north‐east Vietnam)

“…The studied deposits from the Hoanh Bo and Dong Ho areas (Figures 1-2) outcrop in a more or less east-west oriented depression referred to as the Hoanh Bo Trough, which in turn is sometimes subdivided into the Dong Ho and Cua Luc troughs (Figure 1c) (e.g., Fyhn et al, 2018;Petersen, Tru, Nielsen, Duc, & Nytoft, 2005;Tru, Diep, Quan, Hung, & Hien, 2002). Moreover, in some papers, the names Hoanh Bo and Dong Ho basins have also been employed (e.g., Song et al, 2021;Tha et al, 2015Tha et al, , 2017Trung, Bat, An, Khoi, & Hieu, 1999;Viet, 2003).…”