An Online Guide to Sequence Stratigraphy：在线指南，层序地层学.doc

An Online Guide to Sequence Stratigraphy This online guide is primarily aimed at the application of sequence stratigraphy to outcrops. As a result, none of the examples deal with topics related specifically to cores, well logs, or most significantly, seismic. Perhaps the best way to work through this online guide is to start with accommodation and to continue down the list of topics from there. Many of the illustrations in this online introduction to sequence stratigraphy are modified from the figures in Van Wagoner et al.s Siliciclastic Sequence Stratigraphy in Well Logs, Cores, and Outcrops (AAPG Methods in Exploration #7). Interested readers should study that reference and other references in the Further Reading section for a fuller explanation of the concepts introduced here. Accommodation The Accommodation Space Equation Over long time scales (105 - 108 years), sediment accumulation is strongly controlled by changes in eustatic sea level, tectonic subsidence rates, and climatic effects on the production of sedimentary grains. Several of these factors are linked to one another through the accommodation space equation. This balance of terms is most easily explained for marine sediments, but can be easily modified to include terrestrial sedimentation. A number of processes can cause the surface of the oceans to move up and down relative to the center of the earth. The distance from the sea surface to the center of the earth is eustatic sea level. In addition, the lithosphere can also move up and down relative to the center of the earth, and changes in the distance from some arbitrarily chosen reference horizon and the center of the earth are called uplift or subsidence. The distance between this reference horizon and the sea surface is called relative sea level or accommodation space.  Acommmodation space can be filled with sediments or water. The distance between the sediment/water interface and the sea surface is known as water depth. The accommodation space