青藏高原古近纪—新近纪古湖泊的特征及分布

通过野外地质调查,结合前人资料和遥感影像解译,对青藏高原古近纪—新近纪湖相地层进行了划分与对比,确定了湖相地层的地域分布。根据古近纪—新近纪湖相地层的展布范围,初步圈定出了63个古湖泊,划分出5个成湖阶段、13个成湖期,其统计总面积大于200×104km2。古湖泊的规模、形态、展布方向明显受构造和古地理的制约。研究表明,古近纪时期的古湖泊主要分布在高原的东北部地区,新近纪时期的古湖泊主要分布在高原的西南部地区,两者之间为过渡地带。青藏高原古近纪—新近纪古湖泊的演化,从时间上讲,有从老到新面积逐渐加大的趋势;从迁移方向上讲,有古湖泊的湖相沉积由东北向西南方向逐渐迁移、古湖泊的年龄由老变新的规律。

Characteristics and distribution of Paleogene-Neogene paleolakes on the Qinghai-Tibet Plateau.

The Paleogene-Neogene lacustrine strata on the Qinghai-Tibet Plateau are divided and correlated and their distribution are determined on the basis of field geological survey, combined with previous data and interpretation of remote sensing images. Sixty-three paleolakes are delineated and 13 lake-forming phase and 5 lake-forming stages distinguished. The total area of these paleolakes is estimated to be >2 million km2. The size, shape and distribution direction of the paleolakes were apparently constrained by structure and paleogeography. Study indicates that: the Paleogene paleolakes were mainly distributed in the northeast of the Qinghai-Tibet Plateau and the Neogene paleolakes mainly in the southwest plateau; the area between the two parts is a zone of transition. In term of time, the Paleogene-Neogene paleolakes of the plateau had a trend to increase gradually in area from the early to late stages. In terms of the migration direction, the depocenter of the paleolakes migrated gradually from northeast to southwest with time.