Abstract:

Based on the boundary differences between schools in the recommended scenarios of standardization of sequence stratigraphy, this paper analyses the designed history of sequence boundaries that are respectively placed on oneeighth periodicity of sea level, lowest of relative sea level and the highest of base level. The original conceptual model of sequences, recognized by Sloss in the North American Craton between Cordilleran Miogeosyncline and Appalachian Miogeosyncline, and biostratigraphy have proved that subaerial unconformities not only wedged into sequences entirely but also enclosed them regionally; this transforming ideal is likely to be helpful to further development for sequence stratigraphy. Meanwhile, the empiricallybased outcrop of Jijihu modern subaqueous aggradational fan (SAF) has proved that sequence boundaries are the poolwards remnant maximum flooding surface (RMFS) and their landwards correlative subaerial unconformities (CSU). This definition of sequence boundary may be considered to be used in siliciclastic settings. Comparing three scenarios respectively bounded by base surface of forced regression (BSFR), top of forced regressive deposits and RMFS+CSU, this paper suggests that the ideal of subaerial unconformities enclosing sequences return to that of wedging and enclosing sequences. Moreover, it has been discussed as follows: (1) the periodicity of shoreline trajectory should be used to restrict sequence boundary; (2) the strata relativity above and below subaerial unconformity are laterally negative to the development time interval of subaerial unconformity.

Key words: sequence stratigraphy, sequence boundary, remnant maximum flooding surface (RMFS), correlative subaerial unconformity (CSU), subaerial unconformity.