禄丰古猿化石地点地层概述

STRATIGRAPHIC SUMMARIZATION OF RAMAPITHECUS FOSSIL LOCALITY, LUFENG, YUNNAN

本文较详尽地记述了云南禄丰古猿化石地点附近的地质、地貌、地层情况以及产出古猿及大量脊椎动物化石的剖面。

Lufeng is a county of Yunnan Province, about 60 km. to the west of Kunming city (Fig. 1). Shihuiba locality (No. 75033 IVPP) (1024' E, 251'N) is situated on the southern slope of Miaoshanpo Hill, about 9 km.north of Lufeng county. Geomorphologically, Lufeng area is a small block basin, located in the east of the middle Plateau of Yunnan. Average height of it is about 1560 m. above sea level. The basin extends about 12 km. from south to north and about 2-3 km. from east to west. In its northern end, the most narrow part is only 0.3-0.5 km. There are three rivers (the West River, the East River and the South River) in the basin. They join near Lufeng county and then is called Xings.u River (Fig. 2). The form and development of Lufeng basin were controled by a series of faults of south-north direction. The base and margin of the basin consist of strata of Presinian period mainly, in addition, Jurassic and Cretacious periods. The distribution of Ceno-zoic beds is only restricted to the piedmont or the center of the basin. The strata of Presinian period called Kunyang Group, is a suite of thick metamor-phic limestone and mudstone, topographically expressed as well-round, lowlying mountains and hills. The Mesozoic deposits are so called 'Red Beds'. They are identified as Fengjiahe (Early Jurassic),Zhanghe (Middle Jurassic) and Jiongdihe (Late Cretacious), Matoushan (Early Cretacious) formations respectively. In the Cenozoie strata, the Neogene beds are fluvial-lacustrine swamp deposits, consisting of sand, gravel, sandy clay, clay and lignite, about 30 m. or more in thickness, and exposed in Shihuiba, Tuguancun, Taizicun, Lufeng and Xiabanqiao-Yangjiahuayuan. The Quar-ternary beds are fluvial gravels and terrace deposits, directly overlying on the old bedrock and the terraces of several rivers. Miaoshanpo Hill on which Ramapithecus fossil locality lies consists of Kunyang Group, greyish white, greyish blue and in part pink microlitic dolomitic limestone and purplish grey sericite slate intercalated with secondary belts of quartz. The Section A, B and C were exposed at different locations of a artificial road trough going to the back of the Miaoshanpo Hill for excavating limestone. In addition, the lignite deposits of lacustrine swamp face surrounding the Section D were exposed when Chengkun Railroad was built, the earthy crust of Miaoshanpo Hill was eradicated and pushed to the roadbed of the Railroad. The deposits have been excavated for 9 times since 1975 and the location of the excavated section has been moved much westward. The sequences of the Sections A and D are summarized from top to bottom in turn as following, mainly according to the observations of 1983, also refering to the sections over the years (Fig. 4 and 5). Section A: 1. Dark purple, purple, orange red weathering crust. Earthy deposits with po-rousities and plant roots. There are sands and gravels in the bottom. Average diameter of the gravels is 1-2 cm. The layer is 1.5-3.5 m. in thickness. 2. Yellow, yellowish drab calcareous clay and sandy clay with clear horizontal bedding. Deposits coarsen gradually from lower to upper. The clay is pure and hard, nearly without root casts and holes. It is demarcated from the lower layer by a eleor erosin surface. The space occupied by the layer shows initial landform. Thickness is 2-6 m. 3. Grey, greyish yellow, greyish brown clay with intercalations of sand and gravel. Deposits coarsen gradually from upper to lower. There are 2-3 belts of blackish brown carbonaceous clay. The thickness of each belt is 15-20 cm. About 1.5-3 m. in thickness. 4. Purple sandy clay with sands and gravels and clear bedding. Deposits coarsen downward. The diamater of gravels is 5-25 cm. The elements of them are quartz, sandstone, slate and limestone and so on. There are usually pollution motley and casts of root in the layer. The surface of the deposit was washed and wearthered, it looks like columnar. Exposed thickness is 5 m. The sequences of the Sections B-and C are similar to that of the Section A. Any fossil of ver