新疆尼勒克县圆头山后碰撞花岗斑岩的同位素年代学及地球化学特征

圆头山黑云母花岗斑岩位于尼勒克县城南,岩体普遍发育的铜矿化,以中部碎裂带中矿化最强。岩石具有典型的斑状结构,斑晶由碱性长石和黑云母组成,基质以长石、云母和石英为主,并含有少量的硫化物。圆头山黑云母花岗斑岩的轻重稀土分馏明显,并且明显富集大离子亲石元素(LILE) (除Sr外)和Pb,同时亏损高场强元素(HFSE)和Nb、Ta、P、Ti,显示出弧火山岩的地球化学特征。圆头山黑云母花岗形成年龄为269±3Ma,其源区以具有弧火山岩特征的下地壳为主,同时含有少量的幔源物质,而且在岩体的侵位过程中有高(⁸⁷Sr/⁸⁶Sr)_i (0.706054~0.709228)和高Pb含量(5.05×10^-6~32.5×10^-6)的陆壳物质混染。在下地壳物质熔融过程中,位于下地壳底部的富水和成矿元素的MASH带物质也被圈入,使原始岩浆富水和成矿物质。圆头山黑云母花岗斑形成于碰撞后阶段,岩石的形成主要受岩石圈地幔拆沉作用的控制,而岩石圈地幔的拆沉可能与中亚造山带的垮塌或塔里木地幔柱活动有关。     

东昆仑东段纳赤台岩群变火山岩锆石U-Pb年龄、地球化学特征及其构造意义

纳赤台岩群主要为一套变质火山沉积岩系,是东昆仑东段早古生代构造演化的重要物质记录。变火山岩的锆石U Pb年代学研究结果显示,年龄具有较宽的年龄谱（459～2 729 Ma）,可划分为2 559 Ma、1 341～1 472 Ma、918～1 142 Ma、557～595 Ma、459～497 Ma 5个年龄段,前4组为继承锆石年龄,反映研究区早期构造岩浆事件,459～497 Ma年龄谱段的锆石具有较好的生长韵律环带,为典型的岩浆成因锆石,206Pb/238U加权平均年龄为（474±7.9） Ma （MSWD=0.59,n=11）,代表纳赤台岩群变火山岩形成时代,即形成于奥陶纪。地球化学研究表明,纳赤台岩群变火山岩原岩均为玄武岩,可以划分为两个岩石系列,斜长角闪片岩和角闪片岩为亚碱性拉斑玄武岩。Mg#介于43.09～46.44,反映岩浆经历了一定程度的结晶分异演化;绿帘绿泥钠长片岩属于碱性玄武岩;Mg#介于57.20～76.00,相对接近原始岩浆成分。微量元素特征显示前者具有岛弧火山岩特征,而后者具有E MORB和OIB特征,其岩浆源区更富集。锆石U Pb年代学和地球化学研究表明,纳赤台岩群火山岩形成于早古生代弧后盆地,是原特提斯洋洋壳向北俯冲导致东昆仑地区拉张成弧后小洋盆的物质记录。     

碳纤维增强型灌浆材料实验研究

灌浆材料中加入碳纤维,可显著改善材料固结体的力学性能.通过正交试验,求得普通水泥浆液中碳纤维的最优掺量.在此基础上,添加助剂,配制出的浆液,流动性能较好,结石体抗压强度略高,抗折强度增强.并测试浆液的基本性能,总结碳纤维对结石体的增强机理.     

On the relationship between 100-hPa South Asia High and Mei-yu in Jiangsu province

By analyzing the change of an index for the characteristics of South Asia High and variations of upper-air troughs in 2002–2005,we studied the impact of South Asia high on the beginning and ending of the Mei-yu(i.e.sustained rain corresponding to the ripening season of plum)in Jiangsu province.Statistic verification is conducted on the relationships between the index and the Mei-yu season in 1991–2005 to examine the impacts of the SAH characteristics index on a rain intensity index of Mei-yu and regional distribution of a characteristics index for different annual patterns of Mei-yu.Historical composite is performed of the 100-hPa circulation field for these patterns using the 100-hPa geopotential height of Northern Hemisphere from 2002 to 2005 and 45-year NCEP reanalysis to study the difference in the circulation for different patterns of Mei-yu.Diagnostic and statistic conclusions,which share much in common,have been obtained as follows.(1)The characteristics preceding to and the advancement/retreat of SAH and the movement of westerly troughs are the factors that influence the onset time of the Mei-yu season;after the Mei-yu onset,the progression/withdrawal of SAH and how farther east it extends are determining how long the Mei-yu lasts and when it ends.(2)During the Mei-yu,the general 100-hPa circulation situation and average characteristics of the SAH are well corresponding to the characteristics of the season and annual patterns of Mei-yu.In addition,the averages of the SAH ridgeline and east-extending index for June,July and the Mei-yu season have some implications to the forecast of the index of Mei-yu intensity.These conclusions can be served as powerful means in determining the starting/ending dates, duration and annual pattern of the Mei-yu season.     

轮古东走滑断裂破碎带结构及与油气关系

利用最新处理完成的轮古东300 km2叠前深度偏移地震资料,多手段识别出轮古东气田发育3期4组断裂。断裂控制了裂缝走向与裂缝发育密度,裂缝主要为高角度(45°~75°)构造窄裂缝,沿裂缝存在溶蚀,走向主要为NESW。纵向上,一间房组裂缝发育密度最大(14条/100 m),其次为鹰山组(6条/100 m)和良里塔格组(4条/100 m);平面上,裂缝主要分布在主干断裂周边1 km范围内,随着距断裂距离增大,裂缝发育强度(裂缝线密度)呈指数降低。在此基础上,综合考虑主干断裂及伴生裂缝发育特征,将轮古东断裂破碎带平面上划分为"羽状破碎带、转换破碎带、斜列破碎带、复合破碎带"4种结构,羽状破碎带分布面积最广,是油气最富集的区域,是目前高效井的集中分布区,围绕羽状破碎带的钻探为走滑断裂控储控藏研究和寻找新的油气富集区域提供了新思路。     

Regional Tectonic Transformation in East Kunlun Orogenic Belt in Early Paleozoic: Constraints from the Geochronology and Geochemistry of Helegangnaren Alkali-feldspar Granite

The Helegangnaren feldspar granite exposed in the eastern part of East Kunlun, is characterized by high concentrations of SiO2 and alkaline, low abundances of Fe, Mg and Ca, metaluminous-weak peraluminous. Trace elements analysis shows that the granite is depleted extremely in Ba, Sr and Eu, and rich in some large-ion lithophile elements and high field strength elements. Besides, the granite has high Ga contents, the values of 104(Ga/Al) vary from 2.50 to 2.77, which is mainly greater than the lower limit of A-type granites (2.6), and is higher than the I- and S-type granites’ average (2.1 and 2.28, respectively). Rare earth element (REE) is characterized by relatively high fractionations of light REE (LREE) and heavy REE (HREE) (LREE/HREE=9.3–13.60, (La/Yb)N=10.92–18.02), pronounced negative Eu anomalies (δEu=0.08–0.13), and exhibits right-dipping gull pattern. Major elements, rare elements and trace elements features show the granite is ascribed to A-type granite and A2 subtype in tectonic genetic type. They are plotted into post-collision or within-plate area in a variety of tectonic discriminations. Geological and geochemical data comprehensively suggest that the granite is formed in a post-collision extensive tectonic setting. Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) zircon U-Pb dating yields a weighted mean age of 425?Ma, belonging to Middle Silurian, which is similar to the age of the post-collision geological events in the region. The differences of magmatic rocks in formation age, rocks assemblage and rocks series systematically indicate that the regional tectonic stress regime in the East Kunlun orogenic belt experienced a major transformation from compress to extension in Middle Silurianin, and the Helegangnaren feldspar granite intruded in the early stage of tectonic transformation.     

中国花岗岩型铀矿区域地球化学指示元素特征及异常模式

我国铀矿床主要划分为四大类型,包括花岗岩型铀矿床、火山岩型铀矿床、砂岩型铀矿床和碳硅泥岩型铀矿床。花岗岩型铀矿约占我国已探明铀矿总资源储量的三分之一以上,是我国重要的铀矿化类型。地球化学勘探方法对花岗岩型铀矿床勘查具有良好的效果。根据全国铀矿资源潜力评价项目研究成果,在大量研究中国花岗岩型铀矿化水系沉积物地球化学异常特征基础上,总结了一套对花岗岩型铀矿化勘查稳定的、行之有效的指示元素及其组合,确定了花岗岩型铀矿化地球化学异常模式,并以实例说明典型花岗岩型铀矿化异常模式。水柰沉积物地球化学异常是进行铀矿产预测评价的有效手段,对铀矿资源的潜力评价发挥了重要作用。     

CO2 processes in an alpine grassland ecosystem on the Tibetan Plateau

In this paper, the CO2 concentrations profile from 1.5 m depth in soil to 32 m height in atmosphere were measured from July 2000 to July 2001 in an alpine grassland ecosystem located in the permafrost area on the Tibetan Plateau, which revealed that CO2 concentrations varied greatly during this study period. Mean concentrations during the whole experiment in the atmosphere were absolutely lower than the CO2 concentrations in soil, which resulted in CO2 emissions from the alpine steppe soil to the atmosphere. The highest CO2 concentration was found at a depth of 1.5 m in soil while the lowest CO2 concentration occurred in the atmosphere. Mean CO2 concentrations in soil generally increased with depth. This was the compositive influence of the increasing soil moistures and decreasing soil pH, which induced the increasing biological activities with depth. Temporally, the CO2 concentrations at different layers in air remained a more steady state because of the atmospheric turbulent milking. During the seasonal variations, CO2 concentrations at surface soil interface showed symmetrical patterns, with the lowest accumulation of CO2 occurring in the late winter and the highest CO2 concentration in the growing seasons.     

秦祁接合带造山缝合带磁组构特征及其构造意义

结合构造及磁化率各向异性研究详细解剖了秦祁接合带唐藏—关子镇—武山和新阳—元龙造山缝合带的应变及岩组特征.41个采点168个构造岩样品的平均磁化率全部较低,磁化率椭球形态分析表明其以平面和压扁应变为主,磁化率各向异性度普遍较高,属强变形岩石组构类型,结合野外观察认为其与变形强度明显正相关.此外,磁化率各向异性参数T、P′可能受岩石类型一定程度的影响.磁化率椭球主轴方位与变形密切相关,提供了丰富的岩组信息.两构造带具有类似的岩组特征,磁面理大致分为呈共轭形态的两组,暗示高应变剪切带在平面上可能以网格状形态出露;高倾伏角磁面理与占优势的低倾伏角、近水平磁线理表明了构造带明显的走滑特征,部分高角度磁线理可能与构造带的挤压和（或）转换挤压相关;磁组方法不能简单用于判别复杂强变形带的运动指向,糜棱面理的复杂变化及K_min与构造带夹角过高使其判别结果意义不明,而野外及显微构造观察都表明了构造带的右行走滑特征.上述结果表明,沿缝合带大规模的右行转换挤压形成了秦祁接合带反“S”型的平面构造形态,暗示在南北板块拼合过程中,西秦岭诸中、小块体一定程度的向西挤逸.