Abstract:

Based on detailed observation of outcrops of basin rim and the typical drilling cores in basin，analylogs and interpretation of seismic cross-section，the“four-in-one" response characteristic of critical sequence boundary  surfaces  during the  sedimentary  evolution   of Silurian  to  Devonian in  Tarim Basin  are detailedly researched ( including S/O sequence boundary surface，corresponding to T⁰₇ in seismic corss-section；sequence boundary surface between Upper Silurian and Lowe-Middle Silurian,corresponds to T¹₆ in seismic cross-section;sequence boundary surface between Upper Devonian and Middle Devonian,corresponds to T⁰₆ in seismic cross-section;sequence boundary surface between Carboniferous and Devonian,corresponds to T⁷₅ in seismic cross-section),in other words,characteristics of sequence boundary surfaces in outcrops ,cores,well logs and seimic cross-section.The results show that the sequence boundary surfaces display unconformity in outcrops and cores，saltation in well logs and uplap，downlap or truncation in seismic cross-section.Afterwards,the petroleum geological significance of sequence boundary surface formation is detailedly elaborated as follows：（1）the sequence boundary reflects the conversion of the basin nature in critical period;(2)the sequence boundary is an important channel for oil and gas migration;(3)the sequence boundary surfaces are beneficial to the formation of trap.The acquisition of the thesis research will provide an important foundational geological data further oil and gas exploration of Silurian to Devonain in Tarim Basin.

Key words: Tarim , Basin, Silurian to Devonian, sequence boundary surface, four-in-one, petroleum geologic significance