尕斯库勒盐湖中CO_2-卤水-盐岩相互作用模拟研究

利用PHREEQC软件模拟CO2侵入后,尕斯库勒盐湖中CO2-卤水-岩盐之间的相互作用。CO2侵入卤水层后,卤水中元素的化学形态种类和大小发生变化,特别是碳酸盐型的络合物形态增多。CO2侵入后,除了碳酸盐、石盐和硫酸盐矿物达到饱和被析出外,其余矿物的不饱和程度加剧,卤水的TDS增大,pH值减小。卤水中U的含量在CO2侵入后发生沉淀而减小。研究成果对深入评估区域内盐水层CO2地质封存的环境风险和利用CO2分离提取盐湖卤水中的铀元素提供理论依据。     

2001年秋季风对坦帕湾盐度平衡的影响

利用三维高分辨率有限体积的近海海域模型FVCOM来分析2001年秋季期间风作用对坦帕湾区域盐度平衡的影响。为了区分风的影响,分别设计了两个实验：一个由潮汐和河流作为驱动,另一个由潮汐、河流以及风场共同驱动。结论如下：首先,风作用会使盐度产生变化,能够明显地使坦帕湾内的盐度增加,并导致水平和垂直方向上盐度梯度的减少;随后,本文分析了坦帕湾区域内的盐度平衡,主要的盐度平衡来自于全部（水平和垂直方向上）平流的盐度流量分歧以及除去海峡底部的垂直方向上盐度流量分歧;最后,对由风引起的盐度变化进一步进行分析,结果表明风作用不能改变盐度平衡地位的相对重要性,由风引起的盐度平衡改变高度依靠于特殊的地形,除此之外,全部平流盐度流量分歧和垂直散布盐度通量分歧能够抵消,并且两者都远大于水平散步盐度流量分歧。     

Paratacamite from Gypsum Veins in Sandstones of the Kuqa Basin,Xinjiang, China: Implications for a New Epigenetic Cu Enrichment Mechanism

The Kuqa Basin filled with Paleogene evaporite series is located in the northeast of the Tarim Basin, Xinjiang, China. It is famous for sandstone‐hosted Cu deposits formed by synsedimentary processes. However, our recent studies reveal that there has been another Cu mineralization mechanism in this basin. Field investigations show that there is a close relationship among faults, salt domes, and brine. Cu deposits are mainly located in two east–west‐trending anticlinal belts in the basin, adjacent to salt domes in the belts. Cu minerals in gypsum veins of the Jidike and Kangcun formations have been investigated by SEM, EDS, and X‐ray diffraction methods. The occurrence of paratacamite in gypsum veins has been reported to coexist with glauberite and halite in the joint planes of sandstones. In addition, it occurs accompanying residual crystal salt encrustation in limestone fractures, or in sandstones in dendritic form. These features indicate that the surface‐Cu enrichment in the Kuqa Basin might have originated from Cu‐bearing brine in the underlying evaporite units, which migrated upward along fractures. In addition, the presence of H₂S in the east–west fault belt in the Kuqa Basin, and the discovery of surface sulfur, calcium carbonate, and covellite, suggest thermochemical sulfate reduction near salt domes in the deeper parts of the rock units. This process resulted in the generation of reduced brine and provided a favorable environment for Cu enrichment. Therefore, the surface‐Cu mineralization near salt domes is interpreted to be the result of Cu‐bearing brine migrating upward to the surface along faults (or joints) following the intrusion of deep salt domes. The geological evidence indicates the presence of reducing brine and Cu‐bearing brine near the salt dome in the deeper rocks of the Kuqa Basin, thus making the intrusive contact zone of the salt dome a favorable site for the epigenetic enrichment of Cu. Our study demonstrates that Cu enrichment in the Kuqa Basin resulted not only from synsedimentary deposition but also through epigenetic enrichment associated with salt dome intrusion and brine‐rich fluids.     

Snow disaster characteristics in Palongzangbu River Basin and mitigation countermeasures for road engineering

The Palongzangbu River Basin contains the highest number of maritime province glaciers in China.There are 130 glacial lakes,64 snow avalanche sites and 28 glacial debris flow gullies distributed within the basin.Snow disasters play a controlling role in the Sichuan-Tibet Highway construction,due to the terrain's special characteristics of high altitude and large height differential.Segmentation mitigation countermeasures for the Sichuan-Tibet Highway are presented based on snow disaster severity level and damage mode of the road.In the Ranwu to Midui section,snow avalanches are regional disasters, so the line should be placed in sunny slopes.In the Midui Gully to Yupu section,the line should be placed in shady slopes and at higher elevations to reduce the risk of glacial lake outburst.In the Yupu to Guxiang section,all three snow disasters are minimal.In the Guxiang to Tongmai section,glacier debris flows are the major threat,thus the road should be placed in shady slopes.     

陆相红层型铜铅锌矿床与红层盆地热卤水成矿作用

新疆乌恰县乌拉根超大型铅锌矿是中国发现的首个产于陆相红层盆地中的红层型铅锌矿床,对其成矿作用及成因有多种不同认识,但都将其归入现有的一些矿床类型,如喷流沉积型、砂岩型等,却均不能反映其独特的成矿环境与成矿作用。为此,在广泛收集和研究全国陆相红层盆地及其矿产的地质资料基础上,通过区域地质构造背景、含矿建造、矿床特征、控矿因素、成矿物质来源、成矿流体等方面对比分析,认为乌拉根铅锌矿与中国大量产于陆相盆地内红色建造中的红层铜矿,在矿床特征、控矿条件、矿床成因等方面具有高度的一致性,均为陆相红层盆地热卤水作用的结果,是同一类型的矿床。红层型矿床是地洼区的特有矿产,是地球地质演化到地洼阶段才出现的新的矿床类型,陆相红层盆地热卤水作用是一个完全独立的成矿系统,因此将其作为一个单独的矿床类型——红层型矿床是合理的,既具有重要理论意义,也具有重要的实践意义,为铅锌矿找矿开辟了新的方向和领域。     

羌塘盆地晚侏罗世夏里组磁学参数指示的沉积环境及其成盐意义

羌塘盆地位于青藏高原中部,是一个具有沉积钠盐、钾盐远景的蒸发岩盆地。最近在羌塘盆地上侏罗统夏里组中发现多处具有钾、钠异常的盐泉这一重要的找钾盐线索,然而目前对上侏罗统夏里组的古环境演变仍然不甚了解,限制了对晚侏罗世羌塘盆地的成盐(成钾)条件和可能的层位等重大科学问题的理解。因此本文以热磁分析为主,对羌塘盆地雁石坪地区上侏罗统夏里组沉积物进行高分辨率岩石磁学研究,并讨论其古环境意义。最后,根据成盐(成钾)理论,综合分析羌塘盆地上侏罗统夏里组成盐(成钾)的构造、气候和物源条件。κ-T曲线、磁滞回线和热退磁结果共同表明磁铁矿和赤铁矿是夏里组的主要载磁矿物;磁学参数分析表明夏里组上段赤铁矿含量相对增加,揭示夏里组上段形成于干旱气候环境;综合分析构造、气候和物源条件表明,羌塘盆地上侏罗统夏里组上段最为具备良好的成盐(成钾)条件。     

6600 years of earthquake record in the Julian Alps (Lake Bohinj,Slovenia)

Sequences of lake sediments often form long and continuous records that may be sensitive recorders of seismic shaking. A multi‐proxy analysis of Lake Bohinj sediments associated with a well‐constrained chronology was conducted to reconstruct Holocene seismic activity in the Julian Alps (Slovenia). A seismic reflection survey and sedimentological analyses identified 29 homogenite‐type deposits related to mass‐wasting deposits. The most recent homogenites can be linked to historical regional earthquakes (i.e. 1348 ad , 1511 ad and 1690 ad ) with strong epicentral intensity [greater than ‘damaging’ (VIII ) on the Medvedev–Sponheuer–Karnik scale]. The correlation between the historical earthquake data set and the homogenites identified in a core isolated from local stream inputs, allows interpretation of all similar deposits as earthquake related. This work extends the earthquake chronicle of the last 6600 years in this area with a total of 29 events recorded. The early Holocene sedimentary record is disturbed by a seismic event (6617 ± 94 cal yr bp ) that reworked previously deposited sediment and led to a thick sediment deposit identified in the seismic survey. The period between 3500 cal yr bp and 2000 cal yr bp is characterized by a major destabilization in the watershed by human activities that led to increases in erosion and sedimentation rates. This change increased the lake's sensitivity to recording an earthquake (earthquake‐sensitivity threshold index) with the occurrence of 72 turbidite‐type deposits over this period. The high turbidite frequency identified could be the consequence of this change in lake earthquake sensitivity and thus these turbidites could be triggered by earthquake shaking, as other origins are discarded. This study illustrates why it is not acceptable to propose a return period for seismic activity recorded in lake sediment if the sedimentation rate varies significantly.     

丹霞山世界地质公园蜂窝状洞穴特征及成因分析

蜂窝状洞穴以其精致的形貌和众说纷纭的成因吸引着科研人员和普通大众的兴趣。丹霞山世界地质公园蜂窝状洞穴主要产于晚白垩世丹霞组二段(锦石岩段)风成砂岩的崖壁上。本文以园区长老峰锦石岩寺和睡美人禄意堂两处蜂窝状洞穴为研究对象,通过野外实地调查,了解洞穴生长环境,定量统计分析其形态特征,并采集砂岩样品进行显微镜下观察,探讨洞穴形成与盐风化作用的关系。研究表明:蜂窝状洞穴所在的岩性主要为中—细粒长石岩屑砂岩,发育大型高角度交错层理,渗透性较好;洞穴开口均向下朝向锦江,有利于来自锦江河流的湿润水汽较长时间地保持在小洞内部;洞穴开口基本服从泰森多边形分布。因此,碎屑颗粒相对比较均匀的风成砂岩为丹霞山蜂窝状洞穴的发育提供了重要的岩石基础,锦江河流为盐风化提供了必要的湿润水汽和盐分。在初始发育阶段,从岩壁上最适合盐风化作用的若干个点开始形成细小的坑洼,逐步向同层位扩张。单个小洞穴由于盐风化作用,洞穴内部风化速率大于洞穴开口边缘,导致蜂窝状洞穴内部空间扩大较快。然后,蜂窝状洞穴的发育突破纹层的限制,逐步加大、变深而呈泰森多边形规则分布。最终,随着洞穴加深,在重力、风力的影响下,蜂窝状洞穴隔壁减薄失稳,洞穴消亡。     

中朝边境天池破火山口湖底地形多波束测深探测

为调查天池破火山口湖的基本参数和湖底地形特征,研究破火山口的内部构造、破火山口的组合样式和垮塌堆积分布,本文采用多波束测深方法,对天池湖底地形进行了探测。探测结果显示:天池最大水深值为373.2m,天池水域边界实测周长为13.44km,天池湖水面面积9.4km~2,天池总蓄水量约为19.88×10~8m~3。天池周边分布4个温泉,温度为7~47℃。根据湖底地形推断,现今的天池破火山口形成于千年大喷发。其后,在天池西侧形成一个喷火口,东侧形成一个熔岩丘。天池湖底存在5个较大的破火山口内壁垮塌堆积区,但在湖底未见熔岩流。天池边缘出露的温泉点对应环状断裂,同时反映深部存在岩浆体。     

Geoarchaeological evidence on a Late Bronze Age earthquake,Ohrid Basin (North Macedonia)

Geoarchaeological investigations on the northeastern shore of Lake Ohrid revealed 3.5 m thick deepwater lacustrine sediments overlying terrestrial vegetation macrofossils, worked wood and abundant potsherds dated to the Late Bronze Age (LBA). Distinct contact of deepwater sediment with the sub-aerial weathered limestone bedrock point to a sudden increase in lake level. According to radiocarbon data, catastrophic flooding occurred shortly after 1214 yr bc. Because the area is located in a highly active seismic zone, we propose that this event was caused by tectonically induced, metre-scale coseismic subsidence related to faults bordering the Ohrid alluvial plain. Moreover, this event coincides well with a dramatic switch in the habitation and settlement strategy in the region. More important, however, is the finding that the age of the proposed massive tectonic event and change in habitation lies within the interval of the proposed ‘earthquake storm’ in the eastern Mediterranean dated to 1225–1175 bc. As the Ohrid-Korça zone belongs to the same tectonic province, a relationship between the abovementioned earthquakes and the proposed event can be expected. This research therefore might provide the first direct evidence of a large-scale earthquake event linkable to the LBA collapse of Europe's first urban civilisation in the Aegean.