| WU Xiaochuan,PU Renhai,CHEN Ying,QU Hongjun,SHEN Huailei. 2018. Seismic analysis of early-mid Miocene carbonate platform in the southern Qiongdongnan Basin, South China Sea. Acta Oceanologica Sinica, 37(2):54－65 |
| Seismic analysis of early-mid Miocene carbonate platform in the southern Qiongdongnan Basin, South China Sea |
| 琼东南盆地南部早中新世碳酸盐岩台地的地震解释 |
| Received:October 30, 2016 Revised:October 07, 2011 |
| DOI：10.1007/s13131-017-1128-6 |
| Key words:forward model carbonate rock thickness facies distribution Qiongdongnan Basin |
| 中文关键词: 正演模型 碳酸盐岩 厚度 岩相 琼东南盆地 |
| 基金项目:The National Science and Technology Major Project of China under contract No. 2011ZX05025-006-02; the National Natural Science Foundation of China under contract No. 41390451. |
| Author Name | Affiliation | E-mail | | WU Xiaochuan | State Key Laboratory of Continental Dynamics, Department of Geology, Northwest University, Xi'an 710069, China | | | PU Renhai | State Key Laboratory of Continental Dynamics, Department of Geology, Northwest University, Xi'an 710069, China | purenhai@126.com | | CHEN Ying | CNNOOC Research Institute, Beijing 100028, China | | | QU Hongjun | State Key Laboratory of Continental Dynamics, Department of Geology, Northwest University, Xi'an 710069, China | | | SHEN Huailei | CNNOOC Research Institute, Beijing 100028, China | |
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| Abstract: |
| The southern uplift of the Qiongdongnan Basin is a deepwater area in which no wells have beens drilled. The Miocene-Quaternary strata in the Xisha Islands, which are located 40-100 km to the south, are composed of carbonate reef formations. Paleotectonic and paleogeographic analyses of the basin suggest that the southern uplift experienced favorable geological conditions for the development of carbonate reefs during the Miocene. The high-impedance carbonates have high amplitudes and low frequencies on seismic profiles. The reefs are distributed on paleotectonic highs and are thicker than the contemporaneous formations. A forward model of the variation in carbonate thickness based on lithological and velocity information from wells in nearby regions can simulate the seismic response of carbonates with different thicknesses. We identified several important controlling points for determining the thickness of carbonates from seismic profiles, including the pinchout point, the λ/4 thickness point, and the λ/2 thickness point. We depict a carbonate thickness map in the deepwater area of the southern Qiongdongnan Basin based on this model. The carbonate thickness map, the paleotectonic and paleogeographic background, and the seismic response characteristics of reefs suggest that the carbonates that developed on the southern uplift of the Qiongdongnan Basin during the Miocene were mainly an isolated carbonate platform peninsula and ramp deposits. It consisted of gentle ramp platform, steep slope platform, platform depression, gravity flow, and reef bank facies. |
| 中文摘要: |
| 琼东南盆地南部隆起属于深水勘探潜力区，距其南部40～100km的西沙群岛中新统—第四系均系碳酸盐岩礁滩地层。通过对该盆地的古构造、古地理分析，认为中新世南部隆起具备发育碳酸盐岩礁滩的地质条件。高波阻抗碳酸盐岩在地震剖面上表现为强低频振幅反射，礁滩体分布在古构造高部位，且厚度大于同期地层。从邻区钻井岩性、速度建立的碳酸盐岩厚度变化正演模型模拟出碳酸盐岩不同厚度时的地震响应，找出地震剖面上识别碳酸盐岩厚度的几个重要控制点：尖灭点、λ/4点、λ/2点，据此制作了琼东南盆地南部深水区碳酸盐岩厚度图。根据碳酸盐岩厚度图和古构造、古地理背景以及礁滩地震响应特征可以看出，琼东南盆地南部隆起中新统发育的碳酸盐岩主要为西沙群岛向北伸出的一个半岛式的孤立碳酸盐岩台地和斜坡沉积，由缓坡台地、陡坡台地、台洼、重力流、礁滩等相带组成。 |
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