兰坪中新生代沉积盆地模拟与流体势

本文利用沉积盆地模拟技术对兰坪地区中新生代的古水动力场进行了详细研究，结果表明盆地晚白垩世地下水是由中、西部向南部一带流动，流速约为1．85mm/a-2.93mm/a，平均2．24mm/a。由北部的相对高势区和中西部的相对高势区向金顶－马登一带的相对低势区流动，流速约为1．64mm/a－2.38mm/a，平均2．01mm/a，至古新世，水头增高，水头差90m。到始新世平均流速较古新世时稍有增大，为16．12mm/a－20.90mm/a。云龙组单元的水动力面貌基本雷同于上白垩统。古新世、水头值约0．3m-2.0m。地下水令在盆地西偏北部一带形成一小块相对高势区，并向四周的相对低势区流动，其流速较缓，约为0．65mm/a-1.72mm/a。以始新世，由于金顶一带其相关的渗透系数仍很大（约0.2mm/a-34.16mm/a。综上所述，兰坪盆地上白垩统和云龙组单元水势分布及水动力场面貌同古构造的发展关系密切，金顶－一带则正位于该低势区内，这就为含矿物质的水溶液的运移，聚集提供了良好的构造和水动力条件。

THE SIMULATION AND FLUID POTENTIAL OF THE CENOZOIC SEDIMENTARY BASIN IN LANPING AREA

The Meso Cenozoic palaeohydrodynamic fields in Lanping area was studied by means of sedimentary basinsimulation technique.The results show that groundwater moved from the center and the western part of the basin to the south during Late Cretaceous with a current velocity about 1.85 mm/a~2.93 mm/a and an average about 2.24 mm/a.The groundwater flowed from the northern,central and western parts,where the fluid potential was relatively high,to Jinding Madeng area where the fluid potential was relatively low,with a current speed about 1.64 mm/a~2.38 mm/a and an average about 2.01 mm/a.During Palaeocene,the head of water rose with a difference up to 90 m.The current velocity increased during Eocene compared with Palaeocene,and it was about 16.12 mm/a~20.90 mm/a.The hydrodynamic features of Yunlong Formation unit was similar to that of Upper Cretaceous and the difference of the head of water was about 0.3 m~0.2 m during Palaeocene.Only in the northwestern part of the basin had the groundwater formed a part of relatively high potential area and flowed to the low potential areas with a slow speed of 0.65 mm/a~1.72 mm/a.During Eocene the correlative coefficient of percolation was still high(about 0.2 m/d~3.6 m/d) in Jinding area.This had caused the low fluid potential area lying between the two high fluid potential areas and the current velocity was about 22.33 mm/a~34.16 mm/a.All of these suggested that the fluid potential distribution and hydrodynamic features of the Upper Cretaceous and Yunlong Formation unit in the Lanping Basin were closely related to the development of the palaeostructure,and the Jinding area was located in the zone of the low fluid potential area,which provided favorable structural and hydrodynamic conditions to the migration and accumulation of the mineral bearing solution.