关键词: 现代地貌, 埋藏古地貌, 地震相, 侵蚀面, 海面变化

Abstract: Coral reefs support one of the ecosystems responding to global climate change most rapidly, and part characteristic geomorphology of coral reefs is significant proxy to determine the sea level change. Currently, most of the published results are mainly based on qualitative researches, no matter the research on the modern geomorphology or the buried palaeogeomorphology of coral reefs, quantitative research is relatively scarce. Based on the analyses of shallow seismic profile data collected at Daoming Reefs (DR) in the northern area of the Nansha Islands from August to September in 2017 combined with high resolution Google Earth images, DR is a typical atoll with an island, four cays, seven drying reefs and several submerged reefs now. It could be seen that the form ratic of DR is 0.11, the compactness is approximately 0.52 with the ductility of 4.20, while the development index of reef flat is 0.30. It is obviously that DR is still a semi-open to quasi-enclosed atoll, still in the early development stage of reefs. The zoning of the underwater geomorphic units of DR indicates that its reef structure follows the Darwin’s atoll theory of ‘Upper Truncated Cone’. Furthermore, taking the erosion interfaces and various typical seismic facies buried under the reef flat and lagoon of DR into account, the features of its modern geomorphology and buried palaeogeomorphology of DR could be revealed. It also indicates that there are several stages of its geomorphologic evolution, including three main developing phases and two stagnated phases, While sea level rose in the postglacial period, it has two relatively stable phases at the water depth of 80-90 m and 50 - 60 m. The modern coral reef in DR began to grow in the early Holocene and developed continuously till now. To collect  the core samples at its out slope, reef flat and lagoon in DR, it would be helpful to set up the reliable chronology scale and the local curve of sea level rising, which would be important to reveal the geomorphologic evolution of the coral reefs in northern area of the Nansha Islands and its responses to sea level changes since the postglacial period further.

Key words: Modern geomorphology, buried palaeogeomorphology, seismic facies, erosion interface, sea level change