甘肃西部及邻区区域地质特征与油气勘探方向

按板块构造观点，甘肃西部及邻区可划为中部华北—塔里木板块、北部兴蒙—天山板块和南部祁连—阿尔金板块３个一级、６个二级和９个三级构造单元。依基底性质可分为前寒武纪结晶基底和古生代褶皱基底两大类６个区。区内中新生界盆地有４种类型：陆内裂谷盆地、碰撞带内裂谷盆地、山前裂谷盆地和碰撞带内压性盆地。石炭—二叠系、侏罗系和白垩系为本区油气勘探主要目的层，随盆地的发育成为不同的有利勘探目标与方向。     

城市中心商业区内部功能与步行街

本文研究城市中心商业区商务，居住，交通等内部功能方面的问题，并提出有关在中心商业区设置步行街的一些见解。     

Ductile-brittle transition in pre-Alpine amphibolite facies mylonites during evolution from water-present to water-deficient conditions (Mont Mary nappe, Italian Western Alps)

In the Austroalpine Mont Mary nappe (Italian Western Alps) discrete zones of mylonites–ultramylonites developed from coarse-grained, upper amphibolite facies metapelites of pre-Alpine age. The syn–mylonitic mineral assemblage is quartz–biotite–muscovite–plagioclase–garnet–sillimanite–ilmenite–graphite, and formed via the model hydration reaction: Grt₁+Kfs+H₂O=Bt₂+Ilm₂+Qtz+Ms± Sil .Grain-size reduction of about three orders of magnitude was accompanied by extensive recrystallization of all minerals except sillimanite, and by compositional changes of garnet and biotite. Deformation took place at temperatures of 510–580  °C under low-pressure conditions (0.25–0.45 GPa) and corresponds to the latest stages of pre-Alpine metamorphic evolution. The pre-Alpine mylonitization conditions were close to the brittle-ductile transition, as indicated by syn–mylonitic generation of pseudotachylytes and high differential stress inferred from quartz grain-size piezometry. The brittle-ductile behaviour at a relatively high temperature, and the absence of annealing textures in quartz aggregates, are suggestive of water-deficient conditions during mylonitization. These were accomplished through progressive consumption of water by syn–kinematic hydration reaction and by adsorption onto the greatly increased grain boundary area resulting from dynamic recrystallization.     

滇西褐煤伴生元素锗的富集及评价

阐述了滇西褐煤中锗富集规律及其评价方法和回收利用等问题。指出在滇西122个第三系聚煤盆地中,仅有几个矿区褐煤中富锗,而它们仅分布在澜沧江以西大片花岗岩出露区,可见富锗煤矿区只在特定的地球化学环境中才能形成。含锗价值较大矿区在富锗段最小勘探网度应不小于100m,进一步圈定留待开采过程中加密取样。在充分利用了煤的热值后,应在烟尘及煤灰中回收锗,吨煤中锗的价值比煤本身高得多。     

滇西重力潮汐剖面及地震活动性的研究

1986年以来,笔者先后在下关、丽江台安装了GS-15,ET型重力仪连同弥渡台构成滇西重力潮汐剖面并获得了时间不等的高质量连续观测资料。为统一观测系统,本文将两种不同型号仪器的观测结果归算为武昌台的系统,即ICET(国际固体潮中心)系统。归算表明两台仪器观测结果主波潮次参数δ的偏差小于0.2%、在此基础上,文中讨论了近年来滇西潮汐剖面附近大震前的潮汐变化特征及利用各种物理参数预报地震的可能性。     

乌鲁木齐河源雪密度观测研究

乌鲁木齐河源高山区积雪形成期(10月)积雪层的月平均密度为140kg/m~3,稳定积雪前期(11—2月)和稳定积雪后期(3—4月)雪层的月平均密度分别为190—210kg/m~3和175kg/m~3,非稳定积雪期(5—9月)的新雪密度介于90—125kg/m~3,平均值为112kg/m~3。统计分析表明,冬季积雪层的平均密度不随积雪深度而变化,但与5日平均气温和5日合计降水量呈反相关关系,夏季新雪的密度随雪深的增大而上升,风速对冬季积雪层平均密度和夏季新雪密度均无明显影响作用。     

Petrology of very-high-pressure eclogitic rocks from the Brossasco-Isasca Complex, Dora-Maira Massif, Italian Western Alps

Petrographical and mineral chemical data are given for the eclogites which occur in the garnet-kyanite micaschists of the Penninic Dora-Maira Massif between Brossasco, Isasca and Martiniana (Italian Western Alps) and for a sodic whiteschist associated with the pyrope-coesite whiteschists of Martiniana. The Brossasco-Isasca (BI) eclogites are fine grained, foliated and often mica-rich rocks with a strong preferred orientation of omphacite crystals and white micas. Porphyroblasts of hornblende are common in some varieties, whilst zoisite and kyanite occur occasionally in pale green varieties associated with leucocratic layers with quartz, jadeite and garnet. These features differentiate the BI eclogites from the eclogites that occur in other continental units of the Western Alps, which all belong to type C. Garnet, sodic pyroxene and glaucophane are the major minerals in the sodic whiteschist. Sodic pyroxene in the eclogites is an omphacite often close to Jd₅₀Di₅₀, with very little acmite and virtually no Al^IV, and impure jadeite in the leucocratic layers and in the sodic whiteschist. Garnet is almandine with 20–30 mol. % for each of the pyrope and grossular components in the eclogites and a pyrope-rich variety in the sodic whiteschist. White mica is a variably substituted phengite, and paragonite apparently only occurs as a replacement product of kyanite. Amphibole is hornblende in the eclogites, but the most magnesian glaucophane yet described in the sodic whiteschist. Quartz pseudomorphs of coesite were found occasionally in a few pyroxenes and garnets. The P-T conditions during the VHP event are constrained in the eclogites by reactions which define a field ranging from 27–28 kbar to 35 kbar and from 680 to 750° C. These temperatures are consistent with the results of garnet-pyroxene and garnet-phengite geothermometry which suggest that the eclogites may have equilibrated at around 700° C. In the sodic whiteschist pressures ranging from 29 to 35 kbar can be deduced from the stability of the jadeite-pyrope garnet-glaucophane compatibility. As in the eclogites water activity must have been low. Such conditions are close to the P-T values estimated for the early Alpine recrystallization of the pyrope-coesite rock and, like petrographical and mineralogical features, set aside the BI eclogites from the other eclogites of the Western Alps, instead indicating a close similarity to some of the eclogite bodies occurring in the Adula nappe of the Central Alps. An important corollary is that glaucophane stability, at least in Na- and Mg-rich compositions and under very high pressures, may extend up to 700° C, in agreement with the HT stability limit suggested by experimental studies.     

Oil-generating coals of the San Juan Basin, New Mexico and Colorado, U.S.A.

Coal beds of the Upper Cretaceous Fruitland Formation in the San Juan Basin of northwestern New Mexico and southwestern Colorado have significant liquid hydrocarbon generation potential as indicated by typical Rock-Eval Hydrogen Indexes in the range of 200–400 mg hydrocarbon/g organic carbon (type II and III organic matter). Small, non-commercial quantities of oil have been produced from the coal beds at several locations. The oils are characterized by high pristane/phytane (ca 4) and pristane/n-C₁₇ ratios (ca 1.2), abundant C₂₁₊ alkanes in the C₁₀₊ fraction with a slight predominance of odd carbon-numbered n-alkanes, abundant branched-chain alkanes in the C₁₅₊ region, and a predominance of methylcyclohexane in the C₄----C₁₀ fraction. The oils are indigenous to the Fruitland Formation coals and probably migrated at thermal maturities corresponding to vitrinite reflectance values in the range 0.7–0.8%. Although the oils found to date are not present in commercial amounts, these findings illustrate the potential of some coals to generate and expel oil under conditions of moderate thermal heating.     

Magnetics in geoexploration

The magnetic method is the oldest and one of the most widely used geophysical techniques for exploring the earth’s subsurface. It is a relatively easy and inexpensive tool to employ, being applicable to a wide variety of subsurface exploration problems involving horizontal magnetic property variations occurring from near the base of the crust to within the uppermost meter of soil. Successful applications of the magnetic method require an in-depth understanding of its basic principles and careful field work, data reduction, and interpretation. Commonly, interpretations are limited to qualitative approaches which simply map the spatial location of anomalous subsurface conditions, but under favourable circumstances the technological status of the method will permit more quantitative interpretations involving specification of the nature of the anomalous sources. No other geophysical method provides critical input to such a wide variety of problems. However, seldom does the magnetic method provide the complete answer to an investigation problem. As a result, it is generally used in concert with other geophysical and geological data to limit its interpretational ambiguities.     

西昆仑山加里东期花岗岩类浅识

西昆仑山可能有一个呈NW-SE向展布的加里东期花岗岩带存在.除了地质上的依据和判断以外.带内曾获得两个岩体单矿物钾-氩法年龄资料(445Ma、527.6Ma)及一个锆石铀-铅法年龄值(480.43±5Ma).岩体多属钙碱性系列,可能是一个铜、铅、金、稀有金属成矿远景区.岩带西侧的喀拉塔什—依萨克阿特—他龙深断裂可能是加里东期古板块的边界;而这一深断裂的西南侧的木吉—安大力达坂—康西瓦深断裂则是华力西期塔里木板块与伊朗—冈底斯板块间的界线.