数字高程模型（DEM）是人们研究地表过程、构造地貌的一种行之有效的方法和手段。DEM是地形表面的数字表达，易于三维可视化和统计分析。DEM作为一种空间数据，可以进行各种空间分析，编制平均高程图、山顶面图、谷地面图、局部地形图、平均坡度图和剖面图，从而有效地显示地形特征，预测地表侵蚀量和地形发展趋势。特定盆地充填面的DEM分析是探讨特定地质时期（新生代）以来地表由沉积转入侵蚀、沉积之后隆升过程、隆升速率和剥蚀量、剥蚀速率等地表过程的有效手段，它与大地构造、深部地球物理相结合，可以揭示隆升机制和大陆动力学背景。低起伏侵蚀面的DEM分析有利于定量揭示山脉夷平面分布，结合基岩地质等其他资料综合分析，可揭示侵蚀面的成因，揭示大地构造与地表过程相互关系是未来研究的主要目标之一。

[1] The Dabieshan orogenic belt is a zone of longlived shortening with late-stage extension that formed during Mesozoic time in central China. Regional basin analysis coupled with structural cross sections provides a means of reconstructing the paleogeography of the region from Triassic continental collision through early Tertiary extension. The overall distribution of different basin types in the orogenic belt indicates that there was a prolonged period of shortening throughout the Mesozoic that became less intense over time. Meanwhile, extension became more common from Jurassic into Tertiary time. Either compression or extension was isochronous but limited to different geographic regions and/or crustal levels or alternated repeatedly orogen-wide through time. Nonetheless, the orogen underwent gradual transition from overall shortening and crustal thickening to dominantly extension and rift basin formation although these events overlapped in time from the Jurassic through Early Cretaceous. Penecontemporaneous compression and extension across the orogen may reflect long-term (>100 m.y.) shortening and crustal thickening leading to gravitational spreading of the resultant thick crustal welt. We suspect that this prolonged history of shortening across two nearby (100 km apart) suture zones played some role in the exhumation of ltrahighpressure rocks from beneath the Dabieshan.

During the Late Triassic and Jurassic, three structural belts developed in the western Ordos Basin and adjacent regions of China: the Alxa compressive wedge, the Helanshan struc-tural belt and the Liupanshan fold and thrust belt. Three types of basin also developed: a Late Triassic composite basin with a northwestern Ordos rift sub-basin and a southwestern Ordos fore-land sub-basin; an Early-Middle Jurassic intracratonic basin; and a Late Jurassic foreland-type molasse wedge. It is suggested that these basins resulted from Late Triassic unconstrained lateral extrusion and Jurassic constrained lateral extrusion. The Alxa region is interpreted as an extru-sional wedge bounded by strike-slip deformation which escaped laterally from the indentation of the Liupanshan thrust belt from the south. During the Late Triassic the Sino-Korean Block to the east of Helanshan was controlled by a stress state with nearly E-W trending extension. At this stage extrusion was unconstrained. The Helanshan developed as a rift sub-basin due to trans-tensional tectonics at the lateral margin of the wedge. At this time, a foreland sub-basin was formed in front of the Liupanshan thrust belt. During the Jurassic, the Sino-Korean Block to the east of the Helanshan was gradually compressed westwards and the extrusion structure became constrained. The Early-Middle Jurassic shows a transitional stage from unconstrained to con-strained extrusion, and the Ordos Basin developed as an intracratonic basin. From the latest Middle Jurassic: to the Late Jurassic, intense lateral escape and opposite compression led to the formation of the Helanshan fold and thrust belt and its frontal foreland molasse wedge. At the same time another foreland molasse wedge was developed in front of the Liupanshan thrust belt. The switch from rifting to thrusting in the Helanshan is a result of the changing stress field at theCircum-Pacific plate boundary, the clockwise rotation of the Sino-Korean Block to the east ofthe Helanshan and the anticlockwise rotation of the Alxa Block.

The Mesozoic basins in Yanshan, China underwent several important tectonic transformations, including changes from a pre-Late Triassic marginal cratonic basin to a Late Triassic-Late Jurassic flexural basin and then to a late Late Jurassic-Early Cretaceous rift basin. In response to two violent intraplate deformation at Late Triassic and Late Jurassic, coarse fluvial depositional systems in Xingshikou and Tuchengzi Formations were deposited in front of thrust belts. Controlled by transform and extension faulting, fan deltas and lacustrine systems were deposited in Early Cretaceous basins. The composition of clastic debris in Late Triassic and Late Jurassic flexural basins respectively represents unroofing processes from Proterozoic to Archean and from early deposited, overlying pyroclastic rocks to basement rocks in provenance areas. Restored protobasins were gradually migrated toward nearly NEE to EW-trending from Early Jurassic to early Late Jurassic. The Early Cretaceous basins with a NNE-trending crossed over early-formed basins. The Early-Late Jurassic and Early Cretaceous basins were respectively controlled by different tectonic mechanisms.

A Mesozoic foreland-basin complex formed along the northern Yangtze plate during subduction of this plate under the Qinling-Dabieshan orogenic belt along the Mianlue suture. As the Yangtze plate moved northwestwards and was obliquely subducted under the Qinling–Dabieshan (Middle-Late Triassic), a flysch foredeep developed in the Diebu-Songpan in the western part of the northern Yangtze plate. During the Late Triassic, a nonmarine molasse basin first formed in the eastern part of the northern Yangtze plate in response to initial collision there. This molasse clastic wedge prograded over the former marine basin and was accompanied by a change from high-sinuosity river systems flowing into basinal lakes, to higher gradient braidplains. Complete oceanic closure along the Mianlue suture during the Middle Jurassic produced a more extensive east-west molasse basin with rivers, deltas and lakes. During Late Jurassic through Early Cretaceous, the depocenter of the nonmarine molasse basin migrated continually from east to west because of intracontinental deformation associated with clockwise rotation of the Yangtze plate relative to the North China plate. In this time interval, the basin was again dominated by fluvial and lake-delta deposition and rivers continued to disperse sediments southwards into the basin.