Zhejiang Region Research Articles

Three-dimensional Reconstruction of the Yaolin Cave

This paper reports on three-dimensional reconstruction of the Yaolin Cave in the Karst Region of Zhejiang, China. An object-oriented method was used to represent two cave classes—the class Boundary and the class Inside. The class Boundary included objects of the cave ceiling and the cave floor which are part of the topographical trend of the cave. This trend was determined by integrating topography with landform using TIN modeling. The inside of the cave with stalagmites, stalactites, dripstone-columns, and other objects was built using surveying data, photographs, and such computer graphics techniques as texture mapping and transparency. A stand-alone, 3-D visualization system—Cave3D—was developed on the Windows 98/NT platform to produce 3-D graphics and implement graphics-based computation, spatial query, and analyses. A virtual Yaolin cave was created using VRML97 and Java and posted on the Web.

Tectonic environments of Cenozoic volcanic rocks in China and characteristics of the source regions in the mantle

Extensive volcanism is one of the important features of Cenozoic geology in China. Based on temporal-spatial distribution, the volcanism was associated with three major different geological settings: 1) the continental rift basalts in Northeast and North China; 2) the tension-fault basalts on the continental margins of Southeast China; and 3) the collision-zone high-K volcanics in the Qinghai-Xizang Plateau and its vicinities. The characteristics of “depletion in the south and enrichment in the north” of the China continental mantle are strongly supported by isotopic evidence. The Cenozoic continental mantle of China can be divided, on the basis of isotopic evidence and regionally geological characters, into the following geochemical provinces: 1) the depleted mantle in South China; 2) the primary mantle in Northeast and North China; 3) the hybrid and transitional mantle in the region of Shandong, Anhui, Jiangsu and northern Zhejiang; 4) the depleted mantle around the Bohai Bay and the Lower Liaohe River; 5) the K-metasomatic enriched mantle in the northern part of Northeast China; and 6) the re-cycled enriched mantle in the ancient subduction zone in the Qinghai-Xizang Plateau and its surroundings. These geochemical characteristics on a regional scale must be a reflection of the nature of lithosphere evolution.

Evidence for a counter-wind current in winter off the southeast coast of China

Regarding the current pattern in winter in the near-sea region of Zhejiang, Fujian and Guangdong (including the western and central parts of the Taiwan Strait), oceanographers both at home and abroad had considered unanimously that under the intense influence of the northerly monsoon, the current (not only at the surface but also in the deep and near-bottom layers) flows southwestward with the wind. It was not until the end of the fifties that scientists began to question such a traditional concept.

The effects of Xinanjiang reservoir on precipitation

The Xinanjiang reservoir is located in the mountainous region of Zhejiang and Anhui Provinces. Since the construction of the reservoir in 1959, there was no sufficient amount of stored water during the years 1960–1972. This paper analyzes-the effects of reservoir on precipitation. The results obtained are: (1) The main effects are decreases of summer rainfall and annual rainfall (100 mm at a point 10 km apart from the margin), and slight increase in winter. (2) At the site farther from the reservoir and higher in altitude, annual rainfall increased, 100–200 mm increase at the 50–60 km distancee. (3) The average annual rainfall for the whole basin decreases only by 6 mm or so. (4) The effect changes from year to year. It is less in the rainy year than in the dry year.