The Tectonic Evolution Features Analysis Of The Main Source-reservoir-cap Rock Series In Alar Fault

The source-reservoir-cap rock series tectonic evolution of Alar Fault Zone is the the basis for the oil and gas formation and distribution research of the fault zone, previous research in this area is weak. In this paper, based on a large number of geological, seismic and drilling data,through structural analysis, sedimentary facies analysis and seismic data research on current structural features, the main source-reservoir-cap rock series of stratigraphic thickness variations, various sedimentary strata deposited settling characteristics and features of the shortened and the evolution of the tectonic evolution features of the main reservoir cap rock series of Alar fault in Qaidam Basin to obtain the following conclusions:1. The tectonic features under the the current structure pattern:①. Arar to be broken into two sections, the North West section of the tendency toward the south section,dip a large area in the western two-dimensional work of66.9o, three-dimensional work in the region from west to east tapers to29.1o,north-south section the dip is mainly28.9o, the tendency toward the west near the north-south segment, primarily inclination28.9o;②.Alar off from the maximum vertical fault in Cesi line of three-dimensional work area as measured L600(T6)4575m,whereby the two end becomes smaller, measuring about250meters in the line of Cr650;③.Overall top section was "--" shape,breaking the top of the three-dimensional structure of the highest in the work area between Chessie survey line L600-L700, approximately340meters, was the overall high point to the ends of progressively smaller trends;④.Rock fault surface on both sides of the relationship with the main types of semi-ridge half against the tendency of the valley-like;⑤.Fault zone width maximum work area in a leap L1085at about2500m, thus the East, south overall trend was gradually reduced, the minimum value of less than250meters at both ends.2.The thickness variation features in both sides of strata of the fault under the current structure pattern: ①.Alar breaking leap eastern region, breaking down the larger disk formation change, much in the footwall stratigraphic thickness of the plate, the maximum difference layer Youshashan group-Shizigou (T2’-T1) of about300-500m, while the smallest difference layer next Ganchaigou next paragraph-the paragraph under Ganchaigou (T5-T4) within100meters. Stratigraphic thickness of the disk decreases from East to west, from the measured line to Cesi work area to the northeast to the southwest section of the position gradually becoming reduced to the survey line between L680near the fault section thickness approaches zero; while Yuejin Area stratigraphic footwall stratigraphy is presented from a broken section thickens to the northeast trend, the maximum thickness of the lower layer is the segment Ganchaigou-on Ganchaigou (T4-T3) layer, approximately2000meters; under Cesi region disk formation from the north to the northeast extension of the fault section thickness changed little difference between a few meters to tens of meters; to break the eastern two-dimensional work area, the smaller the plate stratigraphic thickness of about100meters, little change in the footwall stratigraphic thickness, but also shows off the northeast-oriented trend extending from the gradual thickening;②.Arar fault in the vicinity of the work area Cesi L600measuring line, T5-T2’(under Ganchaigou-under Youshashan) and T2’-Q (Youshashan group-Quaternary) activity reached a peak amplitude, T5-T2’activity slightly higher magnitude, was broken at both ends to close to trend gradually decreases to zero; broken T2’-Q Unit faulting rate than millions of years earlier, T5-T2’activity unit amplitude change millions of years more gentle sections, the middle high low ends of the overall trend showed a peak appears in the work area near the fault Cesi dimensional measuring line L620.3. The shorten features of each deposition period:Alar fault T5layer formation horizontal shortening was significantly higher than the other layers, the maximum measured in L425line of about4250m, so the break in the vicinity of L425by squeezing the most intense; T2’layer formation shorten small amount compared to other layers, the reaction in the formation of relatively weak squeeze, squeeze the maximum at the site in L485, shortening level is about2000m.4.The burial and subsidence features of different deposition period:Alar fault buried in various sedimentary characteristics of sedimentation reaction tectonic evolution of its main resercoir cap rock series, the thickness of the overlying strata accumulated between100-2000meters, from west to east the overall trent showed a progressively larger maximum depth of up to6500meters.5. The tectonic evolution features of the main reservoir cap rock series:Alar fault kinematic evolution under Ganchaigou to Quaternay sedimentary period from T2’ front can be devided into two main phases: phase depositon under Ganchaigou-Under Youshashan deposition period (T5-T2’)mainly sinistral stike-slip, and another weak strusting; Youshashan deposition period-Quaternary (T2’-Q) to squezze the main thrust.