Analysis of a Continuative Fog Event in Western Shandong Province

[Objective] The aim was to study a continuative fog event in center and western Shandong Province from December 3 to 7 in 2011. [ Method] Based on regular meteorological data, a continuative heavy fog weather process during December 3 to 7 in 2011 was analyzed from the aspects of weather background, ground factors, T-Inp, and moisture and physical quantity field. [ Result] The heavy fog occurred under then at- mospheric circulation pattern controlled by the straight westerly air flow at 500 hPa middle latitudes, ridge of high pressure at middle and low levels, and weak pressure at the bottom of the surface high. The snowfall process for the formation of fog provided vapor conditions of fog, maintenance and development had benefited from lower layer of the warm and humid airflow. During the heavy fog, wind speed was between 1 and 3 m/s. The dew difference and visibility in the eady period had distinct daily changes, while the difference narrowed in the middle and later stage. Close to the ground was an obvious inversion layer, at the same time in the fog strong period temperature inversion layer were apparent between 700 and 800 hPa, these were helpful for fog formation and development. The stable atmospheric stratification, while low layer of weak convergence ascending motion, high level in the presence of weak divergence subsidence, these were also conducive to the maintenance and development of the fog. [ Conclusion] The study provided theoretical basis for the forecast of fog weather.

The genesis of Archean supracrustal rocks in the western Shandong Province of North China Craton: Constraints on regional crustal evolution

Archean greenstone belts are supracrustal sequences, the lower part of which is usually composed of voluminous ultramafic-mafic volcanics. Intermediate and acid volcanic rocks increase in abundance towards the upper domains. Greenstone belts constitute ~30% of the total volume of Archean cratons, and preserve significant information on the surface environment and magmatism in the early earth, which are useful in unraveling the nature of crustal formation and evolution. The western Shandong Province(WSP) is located at the eastern part of the North China Craton(NCC), where greenstone sequences formed at ~2.7 and ~2.5 Ga were well preserved. The early Neoarchean supracrustal rocks include komatiite-basalt sequence, some meta-sediments of the lower part of the Taishan Group and the Mengjiatun Formation. The volcanism had been correlated to mantle plume, which resulted in vertical crustal accretion. The late Neoarchean supracrustal rocks were composed of metamorphosed felsic volcano-sedimentary sequences and BIFs of the upper part of the Taishan Group and the Jining Group. The geochemical features of the meta-volcanics show calc-alkaline affinities, similar to modern arc-related magmatism, suggesting that the continental crust in the western Shandong Province witnessed horizontal plate movements at ~2.5 Ga. The metasediments and leucosomes in the Qixingtai area display regional upper amphibolite facies metamorphism and anatexis at 2.53–2.50 Ga, coeval with formation of large volumes of crustally-derived granites. These tectono-thermal events suggest that a unified continental crust was formed in the western Shandong Province at the end of Neoarchean.

Delineation of Potential Mineral Resources RegionBased on Geo-anomaly Unit

The geological anomaly unit method (GAUM) is a new way to delineate and evaluate ore finding targets in line with the “geological anomaly ore finding theory”. Comprehensive ore finding information from geological, geochemical and geophysical data is used for quantitative measurement of the “ore forming geological anomaly unit” in this paper. The main procedures are shown as follows: (1) The geo anomalous events associated with gold mineralization are analyzed in Tongshi gold field; (2) The zonation in the concentrated heavy minerals and the stream sediment elements of ore forming geo anomaly are studied in detail; (3) The deep geological structural framework is deduced by means of the synthetic geological interpretation of gravity and magnetic information; (4) The ore controlling geo anomalies and ore anomalies are chosen as the variables of the favorable ore forming indexes that can be used for the quantitative delineation and evaluation of the potential ore forming regions.