中-新生代塔里木与中亚盐湖链蒸发岩沉积及其控制因素初探

全球性的构造运动末期一般伴着海退和干旱的气候环境,而蒸发岩沉积与大地构造条件紧密相关。中亚卡拉库姆盆地、阿富汗_塔吉克盆地、塔里木盆地自晚侏罗世至中新世以来至少发生了3次大规模海侵_海退旋回,每次海侵_海退均受特提斯构造事件控制。卡拉库姆盆地、阿富汗_塔吉克盆地为晚侏罗世—早白垩世蒸发岩沉积、塔里木盆地的莎车次级盆地为晚白垩世—古新世蒸发岩沉积,库车次级盆地为古新世—中新世蒸发岩沉积,形成特提斯构造域自西向东蒸发岩沉积时代逐渐变新的盐湖链。中亚及塔里木盐湖链在海侵_海退旋回的控制下,至少发生5次大规模的蒸发岩沉积,发育2种不同的蒸发岩沉积序列,分别对应3次海退期蒸发岩沉积序列及2次断续海侵期蒸发岩沉积序列,具体为晚侏罗世晚期(海退期)卡拉库姆盆地、阿富汗_塔吉克盆地蒸发岩沉积;早白垩世—晚白垩世早期(断续海侵期)阿富汗_塔吉克盆地蒸发岩沉积;晚白垩世晚期(海退期)莎车次级盆地蒸发岩沉积;古新世—中新世(断续海侵期)莎车次级盆地、库车次级盆地蒸发岩沉积;中新世晚期—上新世早期(海退期)库车次级盆地蒸发岩沉积。塔里木与中亚古盐湖发育受控于特提斯构造事件及海侵_海退旋回,而海侵_海退旋回又控制2种不同的蒸发岩沉积序列。蒸发岩沉积序列、古盐湖演化阶段、蒸发岩物质来源、沉积环境决定了盐类矿物沉积类型(单一化学岩型、陆缘碎屑岩_化学岩型),卡拉库姆盆地、阿富汗_塔吉克盆地盐类矿物与塔里木盆地相比,种类简单,反映了盆地化学岩与陆源碎屑_化学岩沉积的区别及后期构造运动对盐类矿物种类的主控作用。

Research on evaporite deposit and its controlling factors for saline lake chain of Tarim Basin and Central Asia Basin during Mesozoic-Cenozoic period

The regressive and drought climate conditions always appear at the end of the global tectonic movement, and the evaporite is related to the tectonic conditions. From Late Jurassic to Miocene there occurred at least three times of large-scale transgression-regression cycles in the Karakum basin, Afghan-Tajik basin and Tarim Basin, and each cycle was controlled by the Tethys tectonic events. The saline lake chain came into being by getting newer and newer period of evaporite deposition from west to east in Tethys tectonic area, such as evaporite deposition from late Jurassic to early Cretaceous in Karakum basin and Afghan-Tajik basin, from late Cretaceous to Paleocene in Yakand secondary basin, and from Paleocene to Miocene in Kuqa secondary basin. These basins experienced at least five times of mass deposition of the evaporate and developed two types of evaporite deposit series, corresponding to evaporite deposits in three times of regression period and two times of transgression period. Evaporites in late Jurassic in Karakum basin and Afghan-Tajik basin (regression period), evaporites in early Cretaceous-late Cretaceous in Afghan-Tajik basin (transgression period), evaporites in late Cretaceous in Shache Basin (regression period), evaporites in Paleocene-Miocene in Shache Basin and Kuqa Basin (transgression period), and evaporites in late Miocene-early Pliocene in Kuqa Basin are the evidence for the cycle. The evaportie had to do with the upper Jurassic Gaoerda Formation and lower Cretaceous Almallard formation. The evolution of ancient saline lake was controlled by the Tethys tectonic events and transgression-regression cycles in central Asian basin and Tarim Basin. Two evaporite deposit series were controlled by transgression-regression cycles. The sedimentary types of minerals, single chemical sedimentary rock and continental margin clastic-chemical sedimentary rock were decided by evolution stages of ancient saline lake, material sources and depositional environment. Compared with things in Traim basin, the types of minerals of evaporites in Central Asia basin are not complex, implying the impact of late tectonic movement on the saline mineral species and the difference between the chemical rock and the terrigenous-chemical deposit.