Quaternary Research 52 (1999) 369-380. doi:10.1006/qres.1999.2072Received by publisher: 1999-05-14Harvest Date: 2016-01-04 12:20:38DOI: 10.1006/qres.1999.2072Page Range: 369-38

A morphologically more diverse assemblage of Longfengshaniaceae has been found in the uppermost Ediacaran (Sinian) Jiucheng Member, Yuhucun Formation at Jinning and Jiangchuan, eastern Yunnan, South China. A majority of them are different from the Longfengshania found in the Neoproterozoic Changlongshan Formation, Yanshan Mountain area, North China and the Little Dal Group, North America. They are mainly characterized by a more varied, often thallus-like appearance with no branches, such as oval, pyriform, spindle, shovel, heart, ribbon and balloon shapes, and more sturdy stalk-like projection (stipe) with a smooth connection on the basal part of the thallus. In addition, they appear to have a remarkable attaching organ of lanceolate, shuttle-like or short stem-like structure at the base of the stipe. Six distinct morphological taxa are recognized, including one new genus, two new species and three conformis species. The characteristics of the family and the genus Longfengshania are further discussed in this paper. The new discoveries of these carbonaceous macrofossils identified as Longfengshaniaceae algae on the basis of the diagnostic forms and anastomosis patterns of their thalli and stipes demonstrate that an important evolutionary radiation of metaphytes took place in the last Ediacaran stage. The flourishing of the benthonic thallophytes attached to the substrate from eastern Yunnan and considered to be photosynthetic alga probably provided continuous nutritional habitats for the explosion and diversification of the Early Cambrian "Chengjiang biota".

Qilu Hu is a large (A = 36.9 km2), shallow (z,,, = 6.8 m) lake that lies at an elevation of 1797 m above msl on the Yunnan Plateau, southern China. Lake waters are hard (Mg = 3.2 meq L-', Ca = 1.3 meq L-'), fresh (conductivity = 380 PS cm-I), and productive (Secchi < 40 cm). An 1 l-m sediment core has a basal 14C age of 30960 k 860 B.P. Sediments between 11 m and 6 m are high in% dry weight, rich in clay components Al2O3, Fe,O,, K,O, MgO, and low in organic C (I 6.1%), carbonate-C (< 1.0 %), total N (< 3.2 mg g-'), and total S (I 1.7 mg g-'). Diatoms and pollen indicate open-water conditions between 9.0 m and 6.0 m (13420-l 1790 B.P.). Above 6.0 m, CaCO, and organic matter concentrations increase relative to elastics. The transition marks a change to shallow-water conditions as inferred from diatoms and pollen, and probably reflects a shift to drier climate. Uppermost (80-O cm) red clays were deposited rapidly, probably as a consequence of recent (decades to centuries) riparian disturbances (e.g. agriculture, lake-bottom reclamation, urban development). Dates assigned to events in the Qilu Hu profile are tentative because of potential hard-water-lake error.

The fluorescence properties of dissolved organic matter (DOM) in the water of Lake Fuxian and its adjacent rivers on the Yunnan Plateau, southwestern China, were studied to specify the characterization of DOM in the lake and river waters. The fluorescence properties with the excitation-emission matrix in the water of Lake Fuxian are different from those in the river water. The differences in these properties between the lake and river water could arise not only from their sources but also from the reactivity of the photobleaching of DOM. In the lake, the supplying of allochthonous fluorescent materials from inflowing rivers to the fluorescent DOM is less significant than the photobleaching of fluorescent substances.

This paper has advanced a new method for determining historical earthquakes. Its object of study is lake sediments. The research method is environmental magnetism represented by susceptibility. The purpose is extracting historical earthquake informations from lake sediments to explore the correlation between the turbidity current sediments initiated by the earthquakes and historical earthquakes round Fuxian Lake.

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Well-preserved, silicified Obruchevella from the earliest Cambrian (Meishucun Stage) sequence from Meishucun section in Yunnan Province, China contains distinct cross-partitioning. This suggests that this helically coiled microfossil represents the remains of an oscillatorialean cyanophyta. Obruchevella is a microfossil that exhibits a variety of form that may be produced through degradation. Obruchevella identified in the Meishucun section includes O: parva, O. parvissima, O. delicata, O. meishucunensis and several other morphs which are yet to be identified.

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