delta-fan
1.Bayanhot basin has three depositional systems including lagoon-tidal flat, delta-fan delta and offshore shallow sea.
2.All these indicate that after the collision of India and Euro-Asia blocks, the orogenic zone grew southward and topography changed from higher to lower in the east at the south edge of Qinghai-Tibetan Plateau. This conclusion can be proved by the discovery of the palaeo-Indus delta-fan complex, the studies of the Indus fan and Bengal fan and the topographic feature of the Himalaya at present.
3.Palaeogene Biyang fault depressed lacustrine basin experiences four evolutionary phases:foothill flooding depression→sulfate coastal/shallow lake→normal lake→carbonate or sulfate coastal/shallow lake, in pace of this, the evolutionary process of sedimentary wedge is from fluvial fan→steep slope fan delta→gentle slope fan delta→fluvial fan in southern margin which belongs to steep slope zone, and is fluvial fan→delta→fluvial fan in northern margin which belongs to gentle slope zone.
7.Though the discussion and analysis on the sedimentary feature of late Triassic in western mid-jiangxi and the classification of the sedimentary facies of Anyuan coal bearing strata, it is found that the depositional environment of late Triassic in the study area is a brackish continental-edge lake, to be further divided into five subfacies: half deep lake, shallow lake, lake tidal flat, lake delta and alluvial fan. The feature of each of the subfacies is decribed in this paper.
9.Based on the observation of the outcrops, we studied the details of the sedimental facies in Ganchaigou Formation, and analysed the variety of sedimental facies, including alluvial-fan facies, braided stream facies, fan-delta facies, lacustrine facies, lacustrine floor fan facies and storm deposit facies.
10.Analysis of petroleum geology, reservoir types and distribution in Lujiapu Depression indicates that: the forming and distribution of reservoirs had been controlled by source area, source-reservoir relationship, petrophysical characteristics, sedimentary facies and secondary structure , and oil is most abundant in reservoirs around hydrocarbon kitchen; the upper member of Jiufutang formation which was entrained or embedded in the main oil source layer has well developed reservoir and good petrophysical property and is the principle oil-bearing interval; the mid-fan and fan delta front of nearshore submarine fan is the most favorite facies; the steep slope of the depression mainly consists of structural reservoirs, the slope belt mainly consists of structural-lithologic and updip pinchout reservoirs, the depressed belt mainly consists of lenticular lithologic reservoirs.
