This paper deals with the sedimentary facies and evolution of the Qiantang River (QR) estuary, and the characteristics and formation of the incised valley sequences and the related shallow biogenic gas reservoir, on the basis of analysis of over 500 cores. The result shows that, since the last glaciation, the Late Quaternary formation of the QR estuary area underwent three stages: (1) deep-cutting stage; (2) rapid-filling stage; and (3) burial stage. The fall of global sea level during the last glacial maximum enhanced the fluvial gradient and river cutting, resulting in the formation of the large-scale QR and Taihu incised valleys, with the interfluve being exposed to air on both flanks of the incised valley. Fluvial terraces at the elevations are present near the present QR estuarine mouth, corresponding to 60-70, 90-100 and 115-125m burial depths. The valleys were filled rapidly with fluvial sediments during the post-glacial period; with the rise of sea level, the river mouth migrated to landward, and backwater and retrogressive aggradation was enhanced. The QR and Taihu incised valleys are associated with an early filling and transgressive channel-infilling sequence formation, and a late filling and transgressive floodplain-estuary formation. Subsequently, the QR valley was buried under estuarine-marine and estuarine sand bar sediments. From bottom to top, the incised valley successions can be grouped into four sedimentary facies: river channel, floodplain-estuary, estuary-shallow marine, and estuary sand bar. The thickness of the river channel-infilling deposits is controlled mainly by base level rising, backwater, retrogressive aggradation and neotectonism. Further, localized thickening took place where deeper scour pools were present in the incised valley or fluvial terraces were formed during the fall of elative sea level. During the deposition of the floodplain-estuary facies, the conditions of sea level rise, tidal regime, sediment supply and accommodation space were suitable for the development of a tidal ridge system; the sand lenses associated with this facies may represent a tidal ridge system in the incised valley. At the later stage when the estuarine sand bars were formed, the sedimentary conditions were no longer favourable, resulting in absence of sand ridge deposits. Biogenic gas is stored in the floodplain-estuary sand lenses of the incised valleys. The Changjiang River provides the major sediment supply for the QR estuary sand bar, and the QR carried sediments constitute only a small portion of the deposits.

Late Quaternary shallow biogenic gas reservoirs have been discovered and exploited in the Qiantang River (QR) estuary area, eastern China. The fall of global sea level during the Last Glacial Maximum resulted in the formation of the QR incised valley. From bottom to top, the incised valley successions can be grouped into four sedimentary facies: river channel facies, floodplain-estuarine facies, estuarineshallow marine facies, and estuarine sand bar facies. All commercial biogenic gas pools occur in floodplain-estuarine sand bodies of the QR incised valley and its branches. The deeply incised valleys provided favorable conditions for the generation and accumulation of shallow biogenic gas. The clay beds that serve as the direct cap beds of the gas pools are mostly restricted within the QR incised valley, with burial depths ranging from 30 to 80m, remnant thicknesses of 10-30m, and porosities of 42.2-62.6%. In contrast, the mud beds cover the whole incised valley and occur as indirect cap beds, with burial depths varying from 5 to 35m, thicknesses of 10-20m, and porosities of 50.6-53.9%. The pore-water pressures of clay and mud beds are higher than that of sand bodies, and the difference can be as much as 0.48 MPa. The pore-water pressures of clay or mud beds can exceed the total pore-water pressure and gas pressure of underlying sand reservoirs. Shallow biogenic gas can be completely sealed by the clay and mud beds, which have higher pore-water pressure. The direct cap beds have better sealing ability than the indirect cap beds. Generally, the pore-water pressure dissipation time of clay and mud beds is conspicuously longer than that of sand beds. This indicates that the clay and mud beds have worse permeability and better sealing ability than the sand beds. However, once the gas enters the sand lenses, the pore-water pressure cannot release efficiently.

应用露头层序地层学基本原理和方法，对巢湖凤凰山石炭系剖面进行重新研究。巢湖凤凰山石炭系总厚度为79.02 m，在这个剖面中可以识别出6种主要岩相、18种微相和n个三级沉积层序，其中六个三级沉积层序属于I型沉积层序，三个属于II型沉积层序，缺失第9和第1O沉积层序。三级沉积层序在不同的古地理单元和不同的沉积环境中可以进行对比。根据各微相特征和成因，揭示了沉积间断面上存在的多期古岩溶现象。阐述了三级层序及其对应的三级海平面升降旋回的特征。

对江苏南京孔山和安徽巢湖凤凰山石炭系碳酸盐岩C、O稳定同位素进行了测定。结果表明，苏皖地区石炭纪13C、18O记录是以4个同位素演化阶段为特征，前3个同位素演化阶段与同时代的北美石炭纪相似，仅仅是内部演化特征略有不同，这反映了区域性的沉积环境的不同变化。在金陵组下部、和州组下部、黄龙组中下部和船山组层段13C表现出明显的正漂移，这可能是受植物和生物量增长、有机碳储藏量增加所引起的。18O记录总体上与13C值呈相似的变化趋势。18O增加记录了气候变冷和冰川作用的结果，18O负漂移与气候变暖和冰川消融是一致的。在浅水潮坪环境，大气淡水的淋滤作用使13C和18O值明显降低。

本文从杭州湾地区末次冰期以来的地质背景入手，分析了该区晚第四纪地层层序、深切河谷形成和演化等。末次冰期低海平面时河流侵蚀切割老地层，在本区形成40-110m深的河谷，谷底为区域不整合面，自海向陆方向和平行海岸线方向均为一不等时面，是类层序边界。冰后期地层为一个完整的1类层序，但存在多个小的间断面。初始海泛面也是穿时的，在深切谷地带是滞流沉积物与溯源堆积物之间的界面，在河间地则为古土壤层的顶界面距今7000-6500a左右的浅海相泥质层中部为最大海泛面，是沉积层序中唯一的等时面。海进体系域的河漫滩沉积物为本区生物气藏的主要勘探目的层。