准噶尔盆地中部下侏罗统沉积演化及主控因素

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[分类号］TE122;P618.13 [文献标志码］A

Abstract： There is great potential foroil and gas exploration in the Lower Jurassic Badaowan Formation and SangongheFormation in the central Junggar Basin.The strata are composed of a set of shallowbraided river delta and shore-shallow lake deposits;however，their temporal andspatial distributions，evolution，andcontroling factors are still not clear. Based oncore loggng data and 2D seismic data，and the application of quantitative techniques， suchasintegrated predictionerrorfilteranalysis，theregional isochronousstratigraphyframework，the paleogeomorphological and sedimentary characteristics of the study area are investigated.The results show that in the central JunggarBasin，the Lower Jurasic phasecanbe divided intothreesequences，i.e.，SQ1，SQ2，and SQ3，from botm to top.Lowstand system tract （LST）， transgresive system tract （TST），and highstand system tract （HST）are identified in each sequence， which correspond to three regressive-transgressive cycles.TheLST inthe sequence is dominated bya large area of braided riverdelta plainsand front deposits.The delta retreatedand shallow lakes developed during the TSTand HST periods，which were characterized bysmalldelta plains and a large distribution of fronts.In terms of paleogeomorphological reconstruction，the Early Jurassic paleogeomorphology evolved variedly through the central Junggar Basin and strongly controlled the sedimentarycenters，resulting in a“seesaw-like” migration in theeast-west direction.From SQlto SQ2，the main depocenter was thePEN-1 western depression，which evolved into the Dongdaohaizi depression during the SQ3 period， thus determining the sedimentary distribution and evolution processin the studyarea.On thebasis of theoverallvery low-relief geomorphologybackground，the riseand-fall cycles of lake level fluctuations controlled delta regression and transgression on a large scale.This process promoted the widespread distribution offavorable sand bodies，such as underwater distributary channels and estuary dams along the delta front. The understanding obtained from this study has important reference significance for future studies of sedimentary evolution and the prediction of favorable sand bodies in the study area.

Key words： Junggar Basin； Lower Jurasic； sequence stratigraphy； paleogeomorphology; sedimentary evolution

准噶尔盆地下侏罗统八道湾组和三工河组是准噶尔盆地深层油气勘探的重要层系（王小军等，2021），发育一套连续稳定的浅水辫状河三角洲-滨浅湖沉积（鲍志东等，2002；Zhuetal.，2017），生储盖组合良好，勘探前景广阔（郑胜，2019；陈榈等，2021）。（剩余17234字）