Precambrian Geochronology, Chronotectonic Framework and Model of Chronocrustal Structure of the Zhongtiao Mountains

The Zhongtiao Mountains, a typical exposure area of Precambrian rocks, are a concentration area of vari-ous types of copper deposit. The rocks were dated using several dating methods. Based on the age data ob-tained by means of three methods, several aspects are dealt with: (1) the dating results obtained by differentmethods and their geological implications have been compared; (2) a chronotectonic framework has been con-structed by means of these reliable ages, which indicates that the ages of the rocks of the Proterozoic mobilebelt fall in a time span of 2400 to 2000 Ma during which global magmatic records are lacking and reflects theages of important events in the mobile belt; (3) according to the ages of inherited zircons, neodymium modelage of the depleted mantle sources (T_(DM)) and geochemical and geological data, a model of Precambrianchronocrustal structure has been constructed, representing a typical for the North China craton.

Fluid Inclusion and Carbon-Oxygen Isotope Studies of the Hujiayu Cu Deposit,Zhongtiao Mountains,China:Implications for Synmetamorphic Copper Remobilization

The Hujiayu Cu deposit,representative of the ＂HuBi-type＂ Cu deposits in the Zhongtiao Mountains district in the southern edge of the North China Craton,is primarily hosted in graphitebearing schists and carbonate rocks.The ore minerals comprise mainly chalcopyrite,with minor sphalerite,siegenite[（Co,Ni）_3S_4],and clausthalite[Pb（S,Se）].The gangue minerals are mainly quartz and dolomite,with minor albite.Four fluid inclusion types were recognized in the chalcopyrite-pyrite-dolomite-quartz veins,including CO_2-rich inclusions（type Ⅰ）,low-salinity,liquid-dominated,biphase aqueous inclusions（type Ⅱ）,solid-bearing aqueous inclusions（type Ⅲ）,and solid-bearing aqueous-carbonic inclusions（type Ⅳ）.Type I inclusion can be further divided into two sub-types,i.e.,monophase CO_2 inclusions（type Ⅰa） and biphase CO_2-rich inclusions（with a visible aqueous phase）,and type Ⅲ inclusion is divided into a subtype with a halite daughter mineral（type Ⅲa） and a subtype with multiple solids（type Ⅲb）.Various fluid inclusion assemblages（FIAs） were identified through petrographic observations,and were classified into four groups.The group-1 FIA,consisting of monophase CO_2 inclusions（type Ⅰa）,homogenized into the liquid phase in a large range of temperatures from-1 to 28℃,suggesting post-entrapment modification.The group-2 FIA consists of type Ⅰb,Ⅲb and Ⅳ inclusions,and is interpreted to reflect fluid immiscibility.The group-3 FIA comprises type Ⅱ and Ⅲa inclusions,and the group-4FIA consists of type Ⅱ inclusions with consistent phase ratios.The group-1 and group-2 FIAs are interpreted to be entrapped during mineralization,whereas group-3 and group-4 FIAs probably represent the post-mineralization fluids.The solid CO_2 melting temperatures range from-60.6 to56.6℃ and from-66.0 to-63.4℃ for type Ⅰa and type Ⅳ inclusions,respectively.The homogenization temperatures for type Ⅱ inclusions range from 132 to 170℃ for group-3 FIAs and115 to 219℃ for group-4 FIAs.The halite melting temperatures range from 530 to 562℃ for typeⅢ b and Ⅳ inclusions,whereas those for type Ⅲa inclusions range from 198 to 398℃.Laser Raman and SEM-EDS results show that the gas species in fluid inclusions are mainly CO_2 with minor CH_4,and the solids are dominated by calcite and halite.The calcite in the hosting marble and dolomite in the hydrothermal veins have δ^（13）C_（V-pdb） values of-0.2 to 1.2‰ and-1.2 to-6.3‰,and δ^（18）O_（v-smow） values of 14.0 to 20.8 ‰ and 13.2 to 14.3‰,respectively.The fluid inclusion and carbon-oxygen isotope data suggest that the ore-forming fluids were probably derived from metamorphic fluids,which had reacted with organic matter in sedimentary rocks or graphite and undergone phase separation at 1.4-1.8 kbar and 230-240℃,after peak metamorphism.It is proposed that the Hujiayu Cu deposit consists of two mineralization stages.The early stage mineralization,characterized by disseminated and veinlet copper sulfides,probably took place in an environment similar to sediment-hosted stratiform copper mineralization.Ore minerals formed in this precursor mineralization stage were remobilized and enriched in the late metamorphic hydrothermal stage,leading to the formation of thick quartz-dolomite-sulfides veins.

Effects of environmental factors on species richness patterns of herb layer in Eastern Zhongtiao Mountain

The species richness of herb layer was investigated among 43 plots of forest vegetation in the eastern Zhongtiao Mountain, in southern Shanxi Province, China. The forest vegetation was divided into two major vegetation types such as the deciduous forest and the coniferous forest by the two-way indicator species analysis （TWINSPAN）. The species richness of herb layer was fitted in the topographic and soil feature factors, as well as the topographic relative moisture index （TRMI） by the generalized linear models （GLM）. The results showed that canopy cover and altitude were the most significant environmental factors. Soil pH value and soil nutrients index such as total N, organic matter content had no significant influence. The effect of environment factors on species richness of herb layer had significant difference in vegetation types. For the broad-leaved forest, litter depth and TRMI were the important environment factors. For the coniferous forest, soil clay content was another important environment factor. The range of environmental gradient such as altitude may contribute to the difference.

Main Wild Medical Fungi and Their Functions in Eastern Forest Region of Zhongtiao Mountain in Shanxi Province

A total of 21 species of wild medical fungi have been currently found in Zhongtiao Mountain,including wild Ganoderma spp.,Bai Lingzhi,Ganoderma applanatum（Pers.） Pat.,Phellinus igniarius（L.ex Fr.） in mulberry tree,Phellinus pini,Fomitopsis rosea Karst,Pyropolyporus adamantinus,Fomes fomentarius,Ganoderma mastoporum Pat,Inonotus obliquus,Fuscoporia punctate,Ganoderma tsugae,Trametes versicolor,Trametes orientalis Imaz,Laetiporus sulphureus,Ganoderma capense（Lloyd） Teng,Hericium erinaceus,Lycoperdon bovista,Polyporus umbellatus Fries,Wolfiporia extensa and Cordyceps barnesii Thwaites.In this paper,the main functions of the major fungi species in eastern forest region of Zhongtiao Mountain in Shanxi Province were introduced.

An Experimental Study on the Observation Method of Hydrogen Concentration in Fault Gas

In order to explore the new technology and methods for seismic underground fluid observation,a test study on measurement of hydrogen concentration in fault gas is carried out at the piedmont fault zone of Zhongtiao Mountain. Through the experiment on observation positions,gas collection devices and sampling depths,the paper presents the observation method for fault gas hydrogen concentration by using an online automatic trace hydrogen analyzer. Comparative tests are conducted on the stability and optimum conditions of this type of instrument in the field environment, and the hydrogen concentrations at different measuring points of the same fault are observed. The results show that it is technically feasible to carry out continuous hydrogen concentration on a fault zone. The method proposed in this study could be a useful tool for setting the observation points,choosing a reasonable observation depth and scientific analysis of the observed data.