青藏高原东北部贵德盆地新生代沉积演化与构造隆升

通过对高原东北部贵德盆地新生代地层研究,为恢复高原隆升历史提供依据。贵德盆地形成于渐新世末,其新生代地层可划分出深水砾砂质网状河流、泥石流质网状河流、砾质网状河流、山麓洪积、三角洲、半深湖与浅湖、水下扇三角洲七个沉积相组合体系。根据其沉积相组合和沉积演化揭示出高原隆升过程先后经历了:早期隆升期 (渐新世末 )、较稳定剥蚀夷平期 (早中新世 )、小幅隆升期 (早中新世末 )、稳定剥蚀夷平期 (中中新世至晚中新世 )、持续逐步较快速隆升期 (8.2～ 3.6Ma)、急剧强烈阶段性隆升期 (3.6～ 0Ma) ;其中 3.6Ma±的隆升是新生代构造运动的一个重要分水岭,此前盆地海拔应不超过 10 0 0m,此后构造活动速度明显加速,地形高差显著增大。可见青藏高原的隆升是一个多阶段、不等速和非均变的复杂过程

Tectonic Uplift and Sedimentary Evolution of the Guide Basin in the Northeast Margin of Tibetan Plateau in Cenozoic Era

There are Iots of different viewpoints about the upIift of the Tibetan PIateau in the worId. The paper provides the proofs for recovering the history of the pIateau upIift by studying Cenozoic stratigraphy of Guide Basin in the northeast Tibetan PIateau. Cenozoic stratigraphy was deposited in Guide Basin wideIy and seven sedimentary facies associations are recognized . They are interpreted as the deposits of deep graveIIy braided, deIta, debris-fIow-dominated braided, shaIIow and haIf-deep Iake, fan deIta, graveIIy braided and piedmont proIuviaI systems, respectiveIy. The reIationship between the sedimentation of Guide basin and the upIift of the Tibetan PIateau reveaIs that the PIateau has experienced six phases in Cenozoic era:preIiminary upIift phase（Late OIigocene）, reIativeIy stabIe and denudation pIanation phase（EarIy-Miocene）, IittIe- scaIe upIift phase（Late EarIy-Miocene）, stabIe and denudation pIanation phase（MiddIe MiddIe-Miocene to Late MiddIe- Miocene）, sustain and stepwise upIift phase（8.2 ~ 3.6 Ma）, rapid and intense upIift phase（3.6 ~ 0 Ma）. The upIift in 3.6 Ma is an important stage of Cenozoic tectonic movements, before then the absoiute eievation of Guide Basin was beiow 1 000 m and since then tectonic movement became more active to form more compiex topography. So the upiift of Tibetan Piateau is a process of muitipie phases, uneguai speed, and irreguiar movement.