本文選題：塔西南　切入點：前陸褶皺沖斷帶　出處：《地質(zhì)學(xué)報》2017年08期 　論文類型：期刊論文

【摘要】：塔里木盆地西南緣前陸褶皺沖斷帶發(fā)育被動頂板雙重構(gòu)造(甫沙地區(qū))和背馱盆地(烏泊爾地區(qū))兩種明顯不同的構(gòu)造類型。為了探討它們的不同成因,利用有限差分軟件FLAC開展了一系列二維數(shù)值模擬研究。采用遵循平面應(yīng)變的黏彈塑性本構(gòu)模型,設(shè)置兩個滑脫層和三個能干層。同時考慮基底沉降、同構(gòu)造剝蝕和沉積,縮短速率為8mm/a,剝蝕速率為每年侵蝕基準(zhǔn)面以上高程的3×10-7(相當(dāng)于每1000m每年剝蝕0.3mm)。在基底水平的情況下,采用均一的沉降速率1.6mm/a并以填平補齊的方式進行沉積時,3.5 Ma后發(fā)育成與甫沙地區(qū)相似的被動頂板雙重構(gòu)造。而當(dāng)模型采用中部小兩端大的拱形沉降速度以及填平補齊的沉積時最終發(fā)育成背馱盆地,和烏泊爾地區(qū)地質(zhì)原型接近。模擬結(jié)果表明,同構(gòu)造沉積地層對褶皺沖斷帶的影響巨大,當(dāng)沉積物大量堆積在褶皺沖斷帶前緣時有利于被動頂板雙重構(gòu)造的形成,而沉積物大量堆積在逆沖楔頂與斜坡時則更有利于背馱盆地的發(fā)生。模擬結(jié)果認為甫沙地區(qū)和烏泊爾地區(qū)都接受了填平補齊的沉積方式,但基底沉降差異造成了兩者的構(gòu)造樣式明顯不同。在小范圍內(nèi)(后陸至前陸小于80km),甫沙地區(qū)基底以水平方式發(fā)生沉降,褶皺沖斷帶前緣接受了大量沉積;而烏泊爾地區(qū)基底在擠壓下發(fā)生彎曲,使得后陸發(fā)生了更大的沉降從而接受了更多的沉積。
[Abstract]:The Foreland fold thrust belt in the southwest margin of the Tarim Basin has two distinct structural types: passive roof double structure (Fusha area) and piggyback basin (Wubar area). A series of two-dimensional numerical simulation studies have been carried out by using finite difference software FLAC. The viscoelastic-plastic constitutive model following plane strain is used to set up two slippage layers and three energy dry layers. At the same time, the basement subsidence, the same structure denudation and deposition are taken into account. The shortening rate is 8 mm / a, and the denudation rate is 3 脳 10 ~ (-7) per year above the base level (equivalent to 0.3 mm / 1000 m / year denudation). A uniform subsidence rate of 1.6 mm / a was adopted and the sedimentation time was carried out in a uniform manner at 3.5 Ma, which developed into a passive roof dual structure similar to that in the Fusha area. However, when the model adopted the large arch settlement velocity at the middle and small ends of the model, and the filling process was adopted, the model was developed into a passive roof dual structure similar to that in the Fusha area. The deposition of Buqi eventually developed into a piggyback basin. The simulation results show that the sedimentary strata of the same structure have a great influence on the fold thrust zone, and that the accumulation of sediments in the front edge of the fold thrust belt is favorable to the formation of the passive roof double structure. The sediment accumulation on the top of the thrust wedge and on the slope is more favorable to the occurrence of the piggyback basin. However, the difference of basement subsidence resulted in obvious differences in structural styles between them. In a small range (from the back land to the Foreland is smaller than 80 kmg), the basement in the Fusha area is subsided horizontally, and the front edge of the fold thrust belt receives a large number of deposits. However, the basement of Upoer area was bent under compression, which resulted in greater subsidence of the hind land and acceptance of more deposits.
【作者單位】： 中國科學(xué)院大學(xué)地球科學(xué)計算地球動力學(xué)重點實驗室;中山大學(xué)地球科學(xué)與地質(zhì)工程學(xué)院;
【基金】：中國石油天然氣股份有限公司前陸盆地項目(編號:2016B-0501)資助的成果
【分類號】：P542

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