World‐class Paleogene Oil‐prone Source Rocks From a Cored Lacustrine Syn‐rift Succession, Bach Long Vi Island, Song Hong Basin, Offshore Northern Vietnam

Abstract

Oil-prone source rocks occurring in lacustrine syn-rift successions have generated significant amounts of hydrocarbons in many Cenozoic basins in SE

Linking Paleogene Rifting and Inversion in the Northern Song Hong and Beibuwan Basins, Vietnam, With Left‐Lateral Motion on the Ailao Shan‐Red River Shear Zone

“…In the Chinese part of the Beibuwan Basin, the thickly developed organic‐rich lacustrine mudstones in the Liushagang Formation described as Eocene contrast to the organic lean Weizhou Formation labelled as Oligocene (Huang et al, ; Liu et al, ). The more than 500‐m‐thick organic‐rich, lacustrine succession drilled on the Vietnamese Bach Long Vi Island located in the western Beibuwan Basin only few tens of kilometers from the Chinese‐Vietnamese territorial boundary is highly comparable to the Chinese Liushagang Formation (Figure ; Huang et al, , ; Liu et al, ; Petersen et al, ) and most likely represents more or less the same stratigraphic interval. However, palynostratigraphy attributes the cored Vietnamese section to the Verrutricolporites Pachydermus subzone of the Florschuetzia Trilobata zone suggesting a middle to Late Oligocene age (Tuyen, 2013).…”

“…On Bach Long Vi Island, located in the Vietnamese part of the basin few kilometers from Chinese territory (Figure ), a more than 500‐m‐thick deep lacustrine succession was recently documented (Figure ; Hovikoski et al, ; Petersen et al, ). Similar to the Liushagang Formation, the Vietnamese mudstones are characterized by their very high organic content, but in contrast to the Chinese source rocks, the mudstones from Bach Long Vi Island were tentatively dated as Upper Oligocene based on identification of a sparse microflora consisting mainly of long range spores and pollens attributed to the F .…”

“…Similar to the Liushagang Formation, the Vietnamese mudstones are characterized by their very high organic content, but in contrast to the Chinese source rocks, the mudstones from Bach Long Vi Island were tentatively dated as Upper Oligocene based on identification of a sparse microflora consisting mainly of long range spores and pollens attributed to the F . Verrutricolporites Pachydermus subzone of the Florschuetzia Trilobata biozone (middle to Upper Oligocene) in addition to freshwater dinoflagellates (Petersen et al, ; Tuyen, ). The lacustrine succession on Bach Long Vi Island was previously considered to be Neogene in age based on macro floral fossils (Ky, ), but the more recent ages are substantiated by seismic data along the island that document the strata to be part of an inverted Paleogene graben (Figure ; Fyhn & Phach, ; Fyhn et al, ; Petersen et al, ).…”

“…Verrutricolporites Pachydermus subzone of the Florschuetzia Trilobata biozone (middle to Upper Oligocene) in addition to freshwater dinoflagellates (Petersen et al, ; Tuyen, ). The lacustrine succession on Bach Long Vi Island was previously considered to be Neogene in age based on macro floral fossils (Ky, ), but the more recent ages are substantiated by seismic data along the island that document the strata to be part of an inverted Paleogene graben (Figure ; Fyhn & Phach, ; Fyhn et al, ; Petersen et al, ).…”

“…A 500‐m Paleogene section was drilled and fully cored by Geological Survey of Denmark and Greenland and Vietnam Petroleum Institute (VPI) on Bach Long Vi Island (Petersen et al, ). The core is stored at VPI's core repository in Hanoi and has been analyzed in the Geological Survey of Greenland and Denmark's and VPI's laboratories.…”