Examining the chronology of transgressions since the late Pleistocene in the Fujian coast, southeastern China

Abstract

The chronological framework of late Pleistocene and Holocene transgressional strata along the Fujian coasts in southeastern China were examined using new 14C dates, OSL ages, and diatom data from cores drilled in Longhai. This location was chosen because previous studies in the region have interpreted the occurrence of MIS3, MIS2, and Holocene transgressions. Our study, and a critical review of previous studies, show that 14C dates of bulk samples from coastal areas tend to be erroneously older than the depositional age due to enhanced input of old carbon via erosion of Mesozoic basement rocks from mountainous inlands. Also, OSL dates of deltaic and fluvial sediments either vary widely due to unsuitable luminescence properties of quartz grains or tend to be older than true depositional ages due to partial bleaching. As such, the previously considered late Pleistocene transgression may have occurred in the Holocene. Overall, the early Holocene transgression is well documented along Fujian coast revealing largely consistent early Holocene sea level histories from northern and southern sectors of Fujian coast. However, late Pleistocene transgressions are not well preserved along Fujian coasts, likely due to pervasive erosion. Our examination of the chronology of transgression in Fujian coast suggests cautions for 14C dating of bulk samples and for OSL dating of sediments in fluvial-deltaic settings, and emphasizes the importance of establishing a reliable chronological framework for understanding relative sea level history in this region and in similar settings elsewhere.