A NEW APPROACH OF THE PLEISTOCENE VOLCANIC ROCK STRATA IN THE NORTHERN HAINAN ISLAND
To accurately delineate the stratigraphic sequence of the Pleistocene volcanic rocks in the Qiongbei fault basin in the northern margin of Hainan Island,South China,the stratigraphy and chronology of the volcanic rocks were studied,which is important for engineering geological exploration.Field work,borehole study,and age dating were conducted,based on which the scheme of lithostratigraphic division of the volcanic rocks were revised.The Pleistocene volcanic rocks are composed of two basalt units intercalated by a pyroclastic rock unit.The pyroclastic rocks in Laocheng-Shishan area can be divided into a lower Pleistocene part and an upper Holocene part.The data of OSL dating of red soil(laterite)range from 15.9±0.9 to 35.2±1.9 ka,which constrained the age of the red soil to the Late Pleistocene,and its position should be below the Holocene pyroclastic rocks,rather than between the Pleistocene basalts and Pleistocene pyroclastic rocks.Therefore,the Pleistocene Duowen Formation lost its geological basis and is recommended to be abolished.Based on the lithostratigraphic characteristics and dating results,the Pleistocene volcanic rocks were redefined as the new Daotang Formation consisting of upper,middle and bottom members and being formed in the Late Pleistocene.
Daotang FormationDuowen FormationPleistocenevolcanic rockHainan Island
万方数据
维普
