关键词: 珠江口盆地, 古近系, 文昌组, 层序格架, 沉积特征, 沉积演化

Abstract: Abstract：Based on comprehensive analyses of cores drilling, well logging and seismic data, the stratigraphic characteristics and
sedimentary evolution of the Paleogene Wenchang Formation in the HA area of the Pearl River Mouth Basin was analyzed．Results
show that five sequence boundaries were identified and four third-order sequences were divided in the study area, including SQ1, SQ2,
SQ3 and SQ4. SQ1 was mainly developed in the south, SQ2 and SQ3 were developed in the whole area, and SQ4 was denuded due to
the tectonic uplift of the south and it developed mainly in the northern HA4 area. Braided river delta, fan delta, nearshore subaqueous
fans and beach-bar facies were developed. The period of SQ1 was the beginning of rift in Huizhou sag, and during this period, sediment
supply was not abundant. Fan delta was mainly developed near XJ24 fault and XJ30 fault, and braided river delta was developed in HA
transform zone. During the period of SQ2, fault depression became stronger and the water became deeper, and thus braided river delta
was developed in large scale in the HA transform zone and fan delta became smaller. Beach-bar facies was developed in the H4 area
due to wave washing. During the period of SQ3, fault activities of the south became increasingly stronger, the water became continually
deeper, and thus braided river delta was developed in smaller scale, but the nearshore subaqueous fans and fan delta were developed in
larger scale. During the period of SQ4, fault activities became weaker, the depth of water became shallower, but sediment supply was
abundant. Therefore, large-scale fan delta was developed near to the HZ26 fault, and shallow water delta was distributed in large scale
near to the XJ30 fault. Nevertheless, due to the denudation by tectonic uplift, the residual strata was thinner.

Key words: Pearl River Mouth Basin, Paleogene, Zhujiang Formation, sequence framework, sediment characteristics, sedimentary evolution