ISSN 1009-6248CN 61-1149/P Bimonthly

Supervisor:China Geological Survey

Sponsored by:XI'an Center of China Geological Survey
Geological Society of China

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2007  Vol. 40  No. 1

Abstract:
Beginning with the definition of nature,this study states that the harmony between human beings and nature is an inevitable result of society development. Also,it points out that the earth is the largest nature for human beings and gives some criteria for the harmonious development. However,it seems that the relationship between the earth and human beings is not in harmony and several examples are taken to prove the viewpoint. Accordingly,the author proposes what should be done to achieve the balance between the earth and human beings. First,new thinking about the earth sciences should be adopted. Second,human beings should change their beliefs,respect nature to accomplish the balance between mentality and nature and the ways of the world. Finally,stepping with the progress of society, all of us should review the past and design the future in a scientific way.
Abstract:
The Ordos Basin is a large-scale sedimentary basin in Northwest China. From bottom up,the hydrostratigraphic units in the basin are pre-Cambrian metamorphic rocks,lower-Paleozoic carbonate rocks,upper-Paleozoic to Mesozoic elastic rocks and Cenozoic deposits. The total thickness is up to 6000m. Three groundwater systems are present in basin,based on the geological and hydrogeolgical settings,such as the karst groundwater system,the Cretaceous clasolite groundwater system and the Carbonate-Jurassic and Quaternary groundwater system. On the basis of the three groundwater systems, according to hydraulic connection and presence of uniform hyduaulic and hydrogeochemical fileds,the karst grounewater system is further divided into 10 flow systems and 22 sub-systems,the Cretaceous clasolite groundwater system can be 5 flow systems and 11 sub-systems, and the Carbonate-Jurassic and Quaternary groundwater system is 9 flow systems. The paper systematically discusses regional patterns of the aquifers,hydrogeochemistry and groundwater flow,presents a full assessment of groundwater resources,and puts forward suggestions on rational development of groundwater in the basin.
Abstract:
Located in the area of the Qilian and west Qinling orogenic belts,the Dangchuan granitic batholith is composed of 9 granitic intrusives. Geochemically,the batholith in general is poor in Ga,Rb, Zr and rich in Th,Ta,Hf and HREE. The Devonian and post-Devonian plutons are obviously rich in Th and Hf,but poor in Rb and Co. The FREE,LREE/HREE and δEu of these plutons are similar to the adamellitoids in the northern Qinling. The lithogeochemstry characteristics between all these plutons show an evident similarity in their sources,tectonic environments,and origin,and also continuity and inheritance in evolution. While the Silurian intrusives are obviously rich in Cr,Co,Nb and rich in Y,but poor in Ga,Rb,Zr,FREE, LREE/HREE and BEu. These Silurian intrusives are not only different from the Devonian ones but also different from the contemporaneous dioritoids in the Qinlin-Bashan areas. It has been agued that the Silurian intrusives are island arc dioritoids which were formed during subduction orogenesis,while the Devonian and post-Devonian plutons were derived from crustal sources related to that has relations to crustal uplift or continent rifting during post-orogenic period.
Abstract:
The Mayuan lead-zinc mineralization belt is tectonically located on the southeastern marngin of the Beiba rise in the northern Yangtze platform.The belt is over 60km long and 10~200m wide and can be divided into the southern,eastern and northern zones,in which over 4% rebodies have been delineated. The southern Pb-Zn mineralization zone having 3% rebodies is more than 20 km long and 20~120m wide.The eastern zone with 7 orebodies is 30 km in length and 20~200m in width.The northern zone is over 10 km long and 10~100m wide. The length of orebodies in the area generally ranges from 100 m to~2 560m, thickness in between 0.80~10.01 m, Zn grade is 1.05%~10.82%,and Pb 0.55% and 7.54%. The major orebody is 2 560 m long,1.46~32.53 m thick (averaging 7.60m) and has 1.45%~11.42% Zn (averaging 4.47%).The mineralization belt mainly occurs in psephitic dolomitic breccias of the Sinian Dengying Formation,which is controlled by stratigraphy and structures. The study indicates that the Pb and Zn ore~forming elements probably come from the basement rocks;The initial Pb isotope could be derived from the crust-mantle mixing in the orogenic belt;sulfur isotope composition is enriched in heavy sulfur that may have come from the seawater sulfate in the synchronous sedimentation;the ore is characterized with REE enrichment,obvious fractionation of LREE and flat-pattern of HREE;ore-forming media is thermal brine fluid;both mineralization temperature and pressure are low;the metallogenic epoch is probably in late Dengying epoch of Sinian period.Integrate the geological characteristics and compare Mayuan lead-zinc mineralization belt with the MVT type Pb-Zn ore deposit abroad,we suggest that the mineralizatine type here is similar to the genesis of the MVT type Pb-Zn ore deposit with some differences. It is expected that favourable prospecting is in the areas of Beiba-Mayuan,Yunhe~Miaoba,Yangpingguan-Kuanchuanpu-Fuchuan,Sishang-Zhenba,Zhenping in Shaanxi province,and Zuxi,Shennongjia and Huanling in Hubei province.
Abstract:
The Poshan silver deposit is a typical extra-large stratabound deposit of metamorphosed elastic rock type. Located between the Nanyang and Wucheng basins,it experienced a long and complex geological history and multi-phased formation and evolution. On the basis of sedimentation,diagenesis and metamorphism,its ore-forming processes were suffered superposition of succeeding hydrothermal process and the main mineralization was Caledonian geothermal water leaching and enrichment. The ore-forming material came from the upper and middle Waitoushan formation of the Neoproterozoic. The distribution of the major ore-forming elements display obvious zoning phenomenon-silver enrichment in the upper portion,while zinc in the lower. The element assemblage anomalies of Ag,Pb,Zn,Cd,As,Cu,Mn, and (Sb)are associated with the deposit in the surrounding areas. Based on the summarization of the primary geochemical anomal characteristics of the deposit,the authors have established a model for the primary geochemical anomalies and geochemical criteria for ore prospecting.
Abstract:
As the development of in-situ leaching technique,sandstone-type uranium deposits have become the key prospecting target for uranium resources in China. In-situ leaching applicable sandstone-type uranium deposits are mainly dominated by interlayered oxidation zone. They are also intimately correlated with erosion source area of high uranium setting,weak neo-structural activities,different paleoclimates in sedimentary and mineralization period,favorable lithofacies and lithology,reducers rich in organic or inorganic matter,favorable dynamic condition of underground water runoff. Based on the macroscopical analysis for the enriched areas of typical sandstone-type uranium deposits and relevant mineralization geological conditions in northwest China,this paper points out that there has been the favorable metallogenic geological conditions and in turn prospecting potential in the Turpan-Hami basin,the southern Yili basin and the surroundings of the Ordos basin. Finally,it presents a forecast for the future prospecting on uranium in northwest China where has the similar geological background like the above basins.
Abstract:
Copper is widely utilized in the fields such as electronic industry,machinery,military and agriculture and is definitely indispensable to modernization for a country. In nature,copper exists mainly in such minerals as sulfide,oxide,native copper and copper sulfates,carbonate and silicate. Up to now, about 280 Cu-existing minerals have been discovered,of which 16 minerals are major ones. According to the proportion of Cu-bearing oxide and sulfide in copper ores,the copper ores can be classified as sulfideores in which the proportion of Cu-bearing oxides is less than 10%,mixed-ores which have Cu-bearing oxides is from 10% to 30%,and oxidized ores in which Cu-bearing oxide is more than 30%.In China.the copper deposits are mainly distributed in provinces of Jiangxi,Yunnan,Hubei,Tibet,Gansu,Anhui, Shanxi and Heilongjiang. The general characteristics of these copper deposits are as follows:(1)small scale.(2) dominated by low grade paragenetic and associated ores.(3) porphyry copper is not abundant, which is suitable to be processed at low cost.(4)of the available reserves,the large and high grade copper deposits lie mostly in remote regions,which are difficult to be developed in current economy. In fact,the general situation of copper resources in China is in low reserve,low grade and poor competition in the world. As a whole,the preserved Cu reserve in China is relatively stable,that is,the newly explored reserves are in balances with the consumed reserves. The sharply increasing demand for copper is mainly relied on import.
Abstract:
The Erdaoling mine is located on the western margin of the Mesozoic Odors basin and belongs to continental elastic deposit during the Jurassic period. From the bottom up,the strata are the Fuxian,the Yan'an,the Zhiluo and the Anding Formations. In the past,it was thought that only the Yan'an Formation contains coal in the Jurassic systerm of the basin. However,recent explorations have shown that the Zhiluo Formation also has some minable coal seams in a certain area. After study of rock outcrops,well logs,borehole cores,the sedimentary facies of the Zhiluo Formation has been divided and the rule for coal accumulation was explored,and moreover,the coal-bearing strata were predicted. The author suggests that the Zhiluo Formation belongs to the typical fluvial sedimentary facies,which cab be further refined to the channel,flood-plain and backswamp microfacies. Coal seams are mainly formed in the backswamp microfacies and the spatial distribution of the coal seams is under control of the sand bodies of the channel microfacies.
Abstract:
The Wangzhuang oilfield is a rare heavy oil reservoir of strong water sensitivity at home and abroad. Expansion of clay mineral seriously harms the exploitation. In order to prevent the problem,three expansion-preventatives of KOH,NH2CONH2 and FGW-2 have been chosen in the indoor experiment which includes static compatibility and core mobility experiments. These experiments have achieved excellent effects. But NH2CONH2 (urine) is the best in the three preventatives because it can increase permeability of water phase by 144%.The basic mechanism for that is that NH2CONH2 can transform expansion clay minerals into other mineral of non-expansion. The effect can be comparable with the U. S patent 4,227, 575 report. This study is to use the experiment data and to explore expansion-prevention effect and mechanism.
Abstract:
The soil quality in 29 provinces,cities,municipalities of China and crop harvest are closely correlated with the following chemical elements N,P,K,S, Fe,Mn,Cu,Zn,B,Mo,V.Sr,Ti,Mg, La,Ce,Pr,Nd,Sm,Eu,Y,Gd,Tb,ny, Ho,Er,Tm, Yb,Lu,Ca,Co,Ni,F,Ti,Si,Na,Cr,Pb, Cd,Hg,Se,Ba,Te,Ta and organic matter content,acidity/alkalinity,water and content salt content in soil. The quality of soil provides an excellent foundation to improve crop yield. Hence,we should completely develop and protect the state land resource. This paper brings foreword the object,content, method,administration and prospect of geological study of ecology agriculture in China.