摘要:
东沙隆起珠江组生物礁是珠江口盆地重要的储层类型,礁灰岩主要为珊瑚藻灰岩,分为骨架岩、粘结岩及障积岩。研究区生物礁发育于开阔台地、台地边缘及台地前缘斜坡3类沉积相中,生物礁类型可分为台内点礁、台地边缘堡礁及台缘斜坡塔礁,以台地边缘堡礁为主。珠江组沉积早期,东沙隆起发育滨岸砂质沉积;中期海水逐渐淹没东沙隆起,形成镶边浅水碳酸盐台地,发育生物礁;晚期海侵台地逐渐淹没消亡,被浅海陆棚泥质沉积代替。流花台地厚度最大,最厚达563m,台地顶面地震强反射使外形轮廓清晰,台地内部中-弱振幅至空白反射,连续性降低;惠州台地厚度较流花台地薄,厚度多大于100m,顶界面强反射轮廓清晰,内部层状反射能量强-中振幅、高-中连续、中-低频,局部空白反射;陆丰台地厚约30m,只有一个高连续的强振幅。生物礁地震响应以丘形、箱型、低丘-透镜状为特征,礁顶常为强振幅,内部为波状、有时见前积结构,翼部可见上超和披覆现象等。
关键词:
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东沙隆起
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珠江组
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生物礁
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地震反射
Abstract:
The reef limestones in the Zhujiang Formation on the Dongsha uplift may be classified into three types:framestone, bindstone and bafflestone developed in the open platform, platform-margin and foreslope facies, and composed of the intraplatform patch reefs, platform-margin barrier reefs and foreslope pinnacle reefs, respectively. During the early stages of the deposition of the Zhujiang Formation, the littoral sandy deposits were initiated on the Dongsha uplift, followed by the rimmed shallow-water carbonate platforms during the middle stages. During the late stages, the carbonate platforms were gradually drowned and consumed by trangressions, and then the shallow shelf muddy deposits were accentuated. Among the carbonate platforms, the Liuhua platform has a maximum thickness of 563 m, and displays strongly seismic reflection on the topmost part while moderate-weak amplitudes and reflection and poor continuity in the interior of the platforms. The Huizhou platform with a thickness of more than 100 also displays strongly seismic reflection on the topmost part while strong-moderate amplitudes, high-moderate continuity and moderate-low frequency and locally blank reflection in the interior of the platforms. The Lufeng platform only with a thickness of about 30 m exhibits highly continuous strong amplitudes. The seismic reflection configurations generally display the mound, box, low hills-lenticular forms. The onlapping and draping can be observed as well.
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