Ore-forming Fluid Characteristics of the Saishitang Cu-polymetallic Deposit in Qinghai Province, China

Saishitang Cu-polymetallic deposit is located in the southeast section of Late Paleozoic arcfold in the southeastern margin of Qaidam platform. Accoring to the geological process of the deposit,four mineralization episodes were identified: melt/fluid coexisting period(O),skarn period(A),first sulfide period(B) and second sulfide period(C),and 10 stages were finally subdivided. Three types of inclusions were classified in seven stages,namely crystal bearing inclusions(type I),aqueous inclusions(type II) and pure liquid inclusions(type III). Type I and II inclusions were observed in stage O1,having homogenization temperature from 252 to 431°C,and salinities ranging from 24.3% to 48.0%. Type I inclusion was present in stage A1,having homogenization temperature from 506 to 548°C,and salinities ranging from 39.4% to 44.6%. In stage B1,type II and III inclusions were observed,with homogenization temperature concentrating between 300–400°C,and salinities from 0.4% to 4.3%. Type II inclusions were present in stage B2,with homogenization temperature varying from 403 to 550°C. In stage C1,type I and II inclusion commonly coexisted,and constituted a boiling inclusion group,having homogenization temperatures at 187–463°C,and salinities in a range of 29.4%–46.8% and 2.2%–11.0%. Type II and III inclusions were developed in stage C2,having homogenization temperature at 124–350°C,and salinities ranging between 1.6% and 15.4%. In stage C3,type II and III inclusions were presented,with a homogenization temperature range of 164–360°C,and salinities varying from 4.0% to 11.0%. The results of micro-thermal analysis show that fluids are characterized by high temperature and high salinity in stage O1 and A1,and experienced slight decrease in temperature and dramatic decrease in salinity in stage B1 and B2. In stage C1,the salinity of fluid increased greatly and a further decrease of temperature and salinity occurred in stage C2 and C3. Fluids boiled in stage C1. With calculated pressure of 22 MPa from the trapping temperature of 284–289°C,a mineralization depth of 2.2 km was inferred. Results of Laser Raman Spectroscopy show high density of H2 O,CH4 and CO2 were found as gas composition. H-O isotope study indicates the oreforming fluids were the mixture of magmatic water and meteoric water. Physicochemical parameters of fluids show oxygen and sulfur fugacity experienced a decrease,and redox state is weakly reducing. Along with fluid evolution,oxidation has increased slightly. Comprehensive analysis shows that melt exsolution occurred during the formation of quartz diorite and that metal elements existed and migrated in the form of chlorine complex. Immiscible fluid separation and boiling widely occurred after addition of new fluids,bringing about dissociation of chlorine-complex,resulting in a great deal of copper precipitation. In conclusion,Saishitang deposit,controlled by regional tectonics,is formed by metasomatism between highly fractionated mineralization rock body and wall rock,and belongs to banded skarn Cu-polymetallic deposit.     

华南加里东期金矿床的基本特征

文章分析了安徽月山矿田夕卡岩型矿床形成过程中水岩作用的类型和特征。估算和讨论了水岩作用过程中的质量－体积变化和动力学问题。结论认为：水岩作用对流体成矿系统中夕卡岩和蚀变矿化作用的发生、发展，成矿流体的形成，成矿物质的富集，矿床定位等具有重要意义；水岩作用的水岩比值（W／R）小于0．1；夕卡岩和矿化蚀变分带是开放体系一系列溶解沉淀波反应前锋发生水岩反应后矿物和元素组合的时空分离的结果。     

An Arecibo follow-up study of seven pulsars discovered by Five-hundred-meter Aperture Spherical radio Telescope(FAST)

We present Arecibo 327 MHz confirmation and follow-up studies of seven new pulsars discovered by the Five-hundred-meter Aperture Spherical radio Telescope (FAST).These pulsars are discovered in a pilot program of the Commensal Radio Astronomy FAST Survey (CRAFTS) with the ultra-widebandwidth commissioning receiver.Five of them are normal pulsars and two are extreme nulling slow pulsars.PSR J2111+2132’s dispersion measure (DM:78.5 pc cm~(-3)) is above the upper limits of the two Galactic free electron density models,NE2001 and YMW16,and PSR J2057+2133’s position is out of the Scutum-Crux Arm,making them uniquely useful for improving the Galactic free electron density model in their directions.We present a detailed single pulse analysis for the slow nulling pulsars.We show evidence that PSR J2323+1214’s main pulse component follows a non-Poisson distribution and marginal evidence for a sub-pulse-drift or recurrent period of 32.3±0.4 rotations from PSR J0539+0013.We discuss the implication of our finding to the pulsar radiation mechanism.     

南水北调西线千米深长隧洞围岩构造地球物理勘探

2004年对南水北调引水隧洞西线一期工程中玛柯河－贾曲段20 km深埋长隧洞进行了地质结构面、岩性特征、赋水性等地球物理勘探、工程地质勘查,并进行综合解释以查清勘探区影响引水隧洞工程建设的不良地质体和不良地质构造.本文介绍了CSAMT法隧洞勘探的特点、资料采集的过程及应特别注意的复杂地形资料处理技术,结合其他补充物探手段及地面工程地质勘察结果对20 km深埋长隧洞围岩介质的结构特征进行了解释,指出了可能影响工程的断层、破碎带及异常区     

冀中坳陷中部现今热岩石圈厚度及地热学意义探讨

热岩石圈厚度是研究盆地的构造演化和板块动力学的重要参数,本文通过实测数据构建地壳分层模型,根据热传导的基本原理,计算了冀中坳陷中部的Moho面温度以及热岩石圈厚度,并探讨其地热学意义。结果表明:冀中坳陷中部的Moho面温度分布在500～600℃,西南侧整体温度较东北部高,热岩石圈厚度介于102～122km,其平面展布特征与华北克拉通热岩石圈厚度西厚东薄的特征相吻合,为华北克拉通受太平洋板块西向俯冲导致东部遭受破坏提供了依据,并且较薄的岩石圈使热流更易传导到地壳浅部,成为了该地区热异常的成因背景。     

未来10年我国不同生态区居民点建设占用耕地预测

通过以生态区为单位分析 ,预测 2 0 0 0～ 2 0 10年 10年间人口增长和居民点建设用地需求及其占用耕地面积。研究表明 :全国未来 10年人口净增加 12 6 96万 ,因人口增长造成的居民点建设用地需求 12 6 6 571hm2 ,其中占用耕地达 6 4 5545hm2 。耕地减少最多的是淮北平原、华北平原、长江下游平原、四川盆地丘陵、长江中游平原、闽粤丘陵平原、汾渭谷地等平原区。     

对流移入杭州湾后飑线发展机制分析

利用多源观测资料,对2021年4月30日发生在黄淮地区的一次强对流过程中由不同类型风暴系统造成的极端对流大风进行了探讨。研究表明,此次强对流过程发生在东北冷涡背景下的强风垂直切变和层结不稳定环境中,地面气旋及锋面触发了初始对流,在之后近10 h的传播过程中经历了组织化发展、孤立风暴新生、发展、合并与重组等不同阶段。期间,由两种不同类型风暴产生了特征相异的对流性大风：第一阶段,以江苏淮安站为代表,苏中极端对流性大风（36.2 m/s）是由发展强烈的超级单体风暴引发下击暴流所致。对流风暴低层呈现出明显的钩状回波特征,对应深厚的具有显著气旋性旋转的中气旋,在地面极端大风临近时刻,中气旋存在同时向上和向下拉伸、水平尺度快速收缩过程。贯穿整个风暴的下沉气流位于风暴钩状回波后侧,这支强下沉气流至地面附近迅速向外辐散,伴随风暴内强反射率核快速下降,导致淮安产生时、空尺度小且空间分布显著不连续的极端大风。第二阶段,以江苏南通地区为代表,苏东南地区极端大风的发展过程涉及多尺度天气系统的相互作用。线状对流系统前部存在明显的阵风锋,造成较大范围10级以上的地面大风;南通通州湾极端大风（47.9 m/s）发生在阵风锋后侧,其形成一方面是由于线形对流风暴造成的强冷池与地面冷锋相叠加,形成更强的气压梯度,另一方面与地面中尺度气旋入海过程中的快速发展以及风暴后侧倾斜向前的下沉气流导致的高空风动量下传有关。     

内蒙古固沙造林树木真菌病害区系

系统调查了内蒙古固沙造林树木真菌病害状况,采集到罹病树木１６科３７种（属）,鉴定出病害１２６种、病原真菌７６种,比较了不同树种及不同组织器官的病害类型和病原生态群落组成的差异。根据沙区不同的水热指标与地理条件,讨论了病原物的生态地理区系,并分为乌兰布和沙漠固沙造林区、毛乌素沙地固沙造林区和科尔沁沙地固沙林区。     

Effects of Enclosure on Plant and Soil Restoration in the Junggar Desert

Enclosure is commonly used in the restoration of degraded grasslands. However, the effects of enclosure on grassland plant and soil restoration remain controversial, particularly in deserts. To assess the effects of enclosure on desert plants and soil properties, using high throughput sequencing, the differences between plants and soil were systematically analyzed before and after enclosure construction. The soil organic carbon, total nitrogen and total phosphorus contents of the three desert flora increased and decreased, but the difference was not significant; enclosure increased plant height, coverage, aboveground biomass, and species richness by 58.99%, 59.35%, 33.29%, and 51.21%, respectively, in a Seriphidium transiliense formation; by 15.49%, 33.52%, 20.85%, and 5.13%, respectively, in a Haloxylon persicum formation; and by 83.80%, 31.51%, 76.66% and 33.33%, respectively, in an Anabasis salsa formation. For soil bacteria, enclosure significantly increased the average number of operational taxonomic units and Shannon-Wiener index by 12.74% and 2.92%, respectively, under S. transiliense formation and by 17.08% and 3.17%, respectively, under H. persicum formation. However, enclosure had no significant effect on the average number of operational taxonomic units or Shannon-Wiener index under A. salsa formation. Enclosure significantly increased desert plants, soil bacterial diversity, and desert plant community productivity; however, the increase in soil nutrient content was not significant. These results demonstrate that enclosure is effective for restoring desert ecosystems but may have little effect on the soil nutrient content.