Phanerozoic strata are distributed in several north-south trending zones in the central part of the Changning-Menglian Belt. Four types of Devonian to Triassic stratigraphic successions can be identified: (1) elastics with limestone lenses in the mid-section, changing up-section into alternations of fine elastics and cherts; (2) elastics with chert intercalations and limestone lenses, and topped by Permian basic volcanics; (3) elastics-basic volcanics-carbonates-clastics; and (4) limestones, dolomitic limestones-dark gray thin-bedded limestones, argillaceous limestones, mudstones and siliceous mudstones. Devonian to Triassic cherts occur in different horizons and different zones from east to west. These cherts are usually transitional to their neighboring elastics. There is no continuous Devonian to Middle Triassic chert sequence in the central zone of the Changning-Menglian Belt as Liu et al. (1991,1993) reported. Volcanics and the overlying carbonates described by some workers as 'seamount' sequences are more likely to have formed in a marine environment on continental crust. Succession (4) is newly recognized in the area from Menglai to Yong'an in Cangyuan County and further north to Padi of Gengma County. Basalts, cherts and elastics also appear in this area. Mid-Triassic (very probably Ladinian) radiolarians extracted from bedded cherts in the Ganzhejidi section indicate that they are in higher stratigraphic positions. The change from bedded cherts via siltstones to thick-bedded sandstones with thin-bedded fine intercalations in the Ganzhejidi section and (some other outcrops along the road from Cangyuan to Gengma) suggests a fundamental change of sedimentary environment caused by a rapid increase of a large quantity of detritus supply. These siliciclastic sediments are possibly syn-orogenic deposits.
Fossil materials of Shanita and Hemigordius from a section northeast of the Woniusi (the Woniu Temple) of Baoshan, western Yunnan are described and figured in this paper. Field investigation indicates that fossils of these two foraminifer genera are extremely abundant and form a typical Shanita-Hemigordius assemblage in the so-called 'Cracked Limestone' in the Baoshan area. Preliminary study has revealed that the features of this assemblage, which includes Shanita amosi, S. chagouensis, Hemigordius renzi and H. biconcavus, are similar not only to the Shanita fauna previously reported from the Shazipo Formation in the Zhengkang area, west Yunnan, but also to those from the Permian of Burma, Thailand, Iran and Turkey.
The middle Permian Cryptospirifer fauna （brachiopod） has hitherto been found in more than 30 localities in the Yangtze Platform, South China. Examination of data from various localities shows that it occurs stratigraphically in three intervals in the range from the upper Kungurian to Wordian. In the Baoshan block in western Yunnan the fauna occurs in the basal part of the Daaozi Formation and is of possibly an early Wordian age. Outside China the Cryptospirifer fauna has been reported from central and northwest Iran and central Turkey, where the fauna may have an age around the Wordian／Capitanian boundary. Rapid global warming since the late Early Permian and possession of other suitable environmental factors such as proper substrate, clastic input and water depth enabled the Gondwana-derived Baoshan Block and related tectono-stratigraphic units in Iran and Turkey to host the Cryptospirifer fauna, a fauna evolved in the Yangtze Platform that is a type area of the Cathaysian province.
The rarefaction analysis has been conducted to test the species diversity changes of the Early and Middle Permian fusulinacean fauna in South China. The results reveal that the number of species dramatically increased since the earliest Permian and quickly reached the maximum value in the early Zisongian representing the highest species diversity for the whole Early and Middle Permian. The species diversity stabilized in the plateau through the Zisongian; however, it started to decline in the following Longlinian and sustained a longstanding low level during the mid-Early Permian. With the appearance of new fusulinacean taxa with septulum structures, the number of species raised again in the late-Early Permian, followed by a decline in the Middle Permian Neoschwagerina simplex zone. Although the species diversity increased apparently in the Kuhfengian, it never rebounded back to the same level as in the Early Permian. In the mid-Middle Permian, species diversity began to decrease continuously and led to the disappearance of most fusulinacean species by the end of the Middle Permian.
