摘要
新生代,青藏高原进入陆内造山及其后的整体隆升阶段,据此形成一系列山间断陷盆地,此时期盆地充填古新—始新统牛堡组沉积,即早中期为冲积扇—河流相沉积环境;中期为湖泊三角洲相沉积环境;中—晚期为淡水湖泊相沉积;晚期为陆内盐湖相沉积。通过对牛堡组沉积相的分析,可以提供剥蚀区与沉积区的空间分布情况,间接反映研究区的古地理面貌,故而进一步探讨古近纪盆地演化历程,即由初陷期半封闭型河湖盆,向深陷期开放型湖盆,至收缩期封闭型湖盆的演化过程。同时也从侧面反映构造演化的发展及沉积盆地响应过程与古气候的耦合关系。
In the Cenozoic era,Tibet entered intracontinental orogenic and later uplift stage,so a series of intermountain fault basin formed,the basin filled sediment in Niubao formation of Paleocene-Eocene,the early-middle stage is alluvial fan-fluvial facies sedimentary environment,the middle stage is lake delta facies sedimentary environment,the middle-late stage is fresh lake facies sediment,the later stage is interior lake facies sediment. By analyses the sedimentary facies of Niubao formation,the spatial distribution of denuded zone and depositional zone are known,it reflects the paleogrographic landforms of the target area indirectly,then the basin evaluation process in Paleogene is discussed: semi-closed lake basin in the early sag stage,open lake basin in deep sag stage and close lake basin in contraction stage. Meanwhile,it reflects the coupling relation of structural evaluation,depositonal basin responding process and ancient climate.
引文
武景龙,朱利东,杨文光,等.2011.尼玛盆地南部古近系牛堡组沉积特征及其地质意义[J].华南地质与矿产,27(1):59-63.
白培荣,马德胜,符宏斌,等.2015.西藏当雄县九子拉地区侏罗纪盆地演化特征浅析[J].贵州地质,32(3):216-220.
潘桂棠,王立全,张万年,等.2013.青藏高原及邻区大地构造图及说明书[M].北京:地质出版社,88-90,92-95,135-138.
王立全,潘桂棠,丁俊,等.2013.青藏高原及邻区地质图及说明书[M].北京:地质出版社,217-220.
白培荣,杨育慎,曾禹人,等.2016.西藏恐弄拉地区中侏罗统桑卡拉佣组的厘定及其地质意义[J].贵州地质,33(4):289-293.
曾禹人,黄建国,马德胜,等.2016.西藏班公湖一怒江结合带木嘎岗日岩群时代上限的新证据-来自恐弄拉地区早白垩世早期孢粉化石的报道[J].地质通报,35(12):2027-2032.
西藏地矿局.1997.西藏自治区岩石地层[M].武汉:中国地质大学出版社,253-256.
王开发,杨蕉文,李哲,等.1975.根据孢粉组合推论西藏伦坡拉盆地第三纪地层时代及其古地理[J].地质科学,(4):366-375.
方爱民,阎臻,刘小汉,等.2005.藏南柳区砾岩中古植物化石组合及其特征[J].古生物学报,44(3):435-445.
徐亚东,张克信,王国灿,等.2010.西藏南部吉隆盆地中新世一早更新世孢粉组合带及其地质意义[J].地球科学-中国地质大学学报,35(5):759-770.
熊伟.2014.被子植物叶片化石分散角质层在恢复古环境中的应用[J].资源环境与工程,28(3):337-338.