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1 前 言 广泛的野外工作和海底勘探为建立米沙鄢群岛中新世礁体的沉积模式和把这种礁体构造描述为狭长陆架上的陆架边缘复合堡礁、及伴生在盆地斜坡上的环礁和尖头礁提供了基础。在岩芯和详细的岩石相研究的基础上,本文阐述了这个较完整的礁体沉积模式,并解释了沉积相和成岩相的发育过程,尤其是关于孔隙性。2 地质背景 菲律宾群岛由于晚白垩世到早渐新世受区域板块构造控制的造山运动作用,而发展为活动的火山岛弧体系(图1)。浅海碎屑岩夹皱形礁体的早中新世沉积层是以不整合关系超覆在各种老岩石上面的。在陆相环境中广泛沉积了煤层。中中新统浅海相粒粒-中粒碎屑岩,及渐变的深水相页岩上覆在这些岩性之上。当时,酸性岩浆侵入和火山喷发及安山质火山碎屑岩沉积非常普遍。中中新世,在盆地边缘广泛发育典型的堡礁,虽然再沉积的安山质火山碎屑岩不断地干扰礁体的生长,但它仍控制了广大地区的沉积型式(图2)。强烈的差异性垂
1 INTRODUCTION Extensive field work and seabed exploration To establish the depositional pattern of the Miocene reefs in the Visayas and to characterize this reef structure as a complex reef along the shelf on the long, narrow shelf and the atolls associated with the slopes of the basin And pointed reefs provide the foundation. Based on core and detailed petrographic studies, this paper presents a more complete reef depositional model and explains the development of sedimentary facies and diagenetic facies, especially with regard to porosity. 2 Geological Background The Philippine Archipelago has developed into an active volcanic island arc system (Figure 1) due to the orogeny controlled by regional plate tectonics during the Late Cretaceous to the Early Oligocene. Early Pleistocene sediments in the shallow-sea clastic crinkled reefs overlay unconventional relationships on various older rocks. In the continental environment widely deposited in the coal seam. The Middle Miocene shallow marine-grained clastic rocks and graded deep-water shales overlie these lithologies. At that time, acidic magma intrusion and volcanic eruptions and andesite pyroclastic deposits are very common. During the Middle Miocene, typical barrier reefs were extensively developed on the margin of the basin. Although the re-deposited andesitic pyroclastic rocks constantly interfered with the growth of the reefs, it still controlled sedimentary patterns in a wide area (Figure 2). Strong difference between the vertical