Yingmin, Wang¹, Liu Hao¹, Xin Renchen¹ 
(1) Basin & Reservoir Research Center, University of Petroleum,P R China, BeiJing, China

ABSTRACT: Comparative Investigations of Lacustrine Basin Slope-Breaks and Continental Shelf Slope-Breaks

The slope-break refers to the position where an extensive sudden topographic change occurs. Based on the studies of the Songliao Basin characterized by Cretaceous down-warping, the Jurassic compressional flexural Junger basin and the Bohai Bay Basin characterized by Paleogene rifting, the slope-break has developed in lacustrine basins of different origins. It has the following features similar to the shelf slope-break: 1.The form is similar. All the slope-breaks have features characterized by a gentle dip for the bottom and top sections and a steep dip for the middle section. 2.The dip is similar and it can reach 1~3° for the abrupt slope of the lacustrine basin slope-break. 3.Deep water gravity flow deposits and lowstand systems tracts were developed downwards from the slope-break. Incised valleys were developed near the slope-break. 4.The slope-break and the surrounding areas are favorable exploration fairways for stratigraphic traps and lithological traps. 
However, the lacustine basin slope-break greatly differs from the shelf slope-break in two aspects. 1.The scale of the lacustrine basin slope break is relatively small. The elevation difference for the steep slope in the lacustrine basin generally ranges from tens of meters to several hundreds of meters and the difference in the marine basin generally falls in the range of several hundreds of meters, or even up to one kilometer. 2.The lacustrine basin slope-break is commonly characterized by multiple slope-breaks so that its impacts on sediment deposition and development of lowstand systems tracts are generally complicated.

AAPG Search and Discovery Article #90026©2004 AAPG Annual Meeting, Dallas, Texas, April 18-21, 2004.