Geological Significance Research Articles

The Profiles Based on Ridge and Valley Lines to Extract Shoulder Lines on the Loess Plateau

The shoulder line is fundamental to geomorphic evolution and erosion monitoring research on the Loess Plateau, which represents the boundary between positive terrain (intergully) and negative terrain (inner gully). The existing extraction methods mainly suffer the problems of unclear geological significance, poor landform application, and low efficiency of algorithms. This paper proposes a new loess shoulder line automatic extraction method, in which topographic feature points (ridge and valley points) were used as endpoints to generate continuous profiles, and two parameters, analysis operator size (L) and filter threshold (σ), were created for shoulder point extraction from each profile. This method can be applied to complex landforms such as the continuous shoulder lines of terraces and extracts. Herein, three typical areas on the Dongzhi Plateau were selected to assess the performance of the method, and a digital elevation model (DEM) with a resolution of 5 m was used as source data. The accuracy assessment index was the Euclidean distance offset percentage (EDOP), and the original evaluation method was improved based on Structure from Motion–Multiview Stereo (SfM-MVS) technology. The experimental results showed that the average accuracy of the proposed method in the three test areas reached 89.3%, which is higher than that of the multidirectional hill-shading and P-N methods. Via testing in different areas, it could be concluded that the extraction efficiency was less affected by the area of the test region, and the approach exhibited a suitable robustness. Simultaneously, the optimal values of parameters L and σ were examined. This study increases the possibility of accurate shoulder line extraction in the large area of the Loess Plateau.

Dynamic evolution characteristics of the “source-reservoir” integration of gray marl and its geological significance to unconventional gas: Insights from pyrolysis experiments

The marl–limestone rhythmic strata of the Permian Maokou Formation have been identified as hosts of unconventional gas reservoirs with “source–reservoir” integration. The lack of research on the pore structure evolution of organic-rich carbonate rock restricts gas exploration of these strata. Here, pyrolysis experiments were performed on the Mao-1 carbonate to simulate hydrocarbon generation, expulsion and diagenesis in gray marl from low maturity to overmaturity. The pore structure of this marl is dominated by mesopores and macropores, and the proportion of macropores increases gradually with temperature. The macropores are mainly pores in the organic matter and shrinkage microcracks. Additionally, micropores and mesopores, dominated by clay mineral interlayer pores and pyrite intergranular pores, are developed in the high mature stage and subsequently compressed in the overmature stage. The main contributors to the specific surface area are micropores and mesopores, which are conducive to natural gas adsorption. After the same pyrolysis treatment, the available porosity of grey marl is higher than that of marine/lacustrine shales, and exhibits an obvious decrease in the low mature–mature stage. These suggest that the abundant residual oil generated blocked the organic and inorganic pores in the gray marl, providing a pivotal material foundation for the gas generation. Micropores and mesopores developed during the high mature stage ensure the gas accumulation and preservation. The above indicate the organic-rich carbonate at the high mature–overmature stage (Ro = 1.7%–2.5%) in the Sichuan Basin may be a favorable exploration horizon for unconventional oil and gas.

U-Pb dating of scheelite, wolframite and apatite from the Woxi Au-Sb-W deposit, western Hunan Province and their geological significance

U-Pb dating of scheelite, wolframite and apatite from the Woxi Au-Sb-W deposit, western Hunan Province and their geological significance

Geochronology of anorthite-garnetite in Caozhuang Group of eastern Hebei and its geological significance

位于华北克拉通的冀东曹庄群是中国最古老的变质火山-沉积岩系,由于后期多次强烈的岩浆-构造事件影响,使得曹庄群的原始产状和原岩特征被强烈改造,导致对曹庄群的认识不清。精细刻画后期地质事件、评估其对原岩改造程度,是解决争议的基础。前人报导曹庄群发育有钙长石-钙榴石岩。本工作继续对该岩性开展地质学、岩相学、地球化学和U-Pb年代学研究,查明斜长石中的钙长石端元比例≥90%、石榴子石属铁铝榴石(14~31)-钙铝榴石(23~47)-钙铁榴石(23~61)固溶体、绿帘石将石榴子石和斜长石两种矿物分隔而开。钙铝-钙铁榴石为均质、全消光、无成分环带、无异常光性特征,亏损轻稀土(LREEs)、富集中稀土(MREEs)、略亏损重稀土(HREEs)、具Eu的负异常,地球化学特征显示钙铝-钙铁榴石是在稳定、封闭,由一期/阶段热液流体,在W/R(水/岩)比值较低的情况下,通过扩散交代作用缓慢结晶而成,并非前人所认为的区域变质作用成因。利用钙质榴石的地球化学特征,进一步反演交代流体的物化性质为弱氧化、中性-弱碱性、富Ca²⁺、富Cl^-、温度在250~500℃。通过钙铝-钙铁榴石原位LA-ICP-MS U-Pb年代学工作,得到不一致曲线的上交点年龄为2529±35Ma(MSWD=1.4,n=35),作为其形成年龄,并与共生热液锆石的SIMS U-Pb年龄在误差范围内一致,推测该期流体交代作用发生于~2530Ma,与研究区内新太古代末(~2.5Ga)经历的区域性麻粒岩相-角闪岩相变质作用时代相近。综合前人工作,初步推断此次交代作用对曹庄群部分岩石Sm-Nd体系的改造程度大于近同时发生的区域变质作用。

Discovery of scandium enrichment and its geological significance in the Dawanshan Neoproterozoic metamorphic basalts from the Mouding area in Central Yunnan Province, China

Discovery of scandium enrichment and its geological significance in the Dawanshan Neoproterozoic metamorphic basalts from the Mouding area in Central Yunnan Province, China

Provenance of Cenozoic sediments in the northeastern Gonghe Basin and its geological significance

Provenance of Cenozoic sediments in the northeastern Gonghe Basin and its geological significance

Analyzing the microwave thermal emission features of lunar regolith in Chang’E landing sites and its geologic significance

嫦娥三、四和五号的原位月壤探测为基于嫦娥一、二号卫星微波辐射计数据的月球科学研究提供了重要参考。论文基于嫦娥二号卫星微波辐射计数据，生成了着陆区亮温图；为了消除亮温随纬度变化的影响，突出亮温与月壤成分之间的关系，定义和制作了规则亮温图和亮温差图；基于Kaguya MI数据，制作了研究区氧化亚铁、氧化钛、单斜辉石和橄榄石含量图；结合原位月壤探测成果，系统分析了嫦娥三、四和五号着陆区月壤的微波热辐射特性。主要研究发现包括以下三点：（1）嫦娥五号着陆区具有稳定的亮温表现，表明该地区月壤成分随深度的变化不明显，可以作为微波热辐射异常研究的重要参考；（2）嫦娥三号着陆区微波数据探测范围内月壤存在分层结构，以低频数据为代表的深层、以高频数据探测为代表的浅层和以可见光成果为代表的表层，成分变化很大；（3）在嫦娥四号着陆区发现并提出了微波冷异常的存在，并初步分析了微波冷异常的成因机制。论文研究发现微波辐射计数据可用于月海玄武岩的识别，可以为深化未来的月海岩浆演化研究提供重要的科学参考。

Trace element characteristics of sphalerite in the Haobugao Zn-Pb deposit, Inner Mongolia, and their geological significance

内蒙古浩布高铅锌矿床位于大兴安岭南段黄岗-甘珠尔庙成矿带,该带是我国北方重要的铅锌多金属成矿带之一。目前,浩布高矿床闪锌矿微量元素赋存机制尚不清晰,矿床成因类型亦存在一定的争议。本研究采用激光剥蚀电感耦合等离子体质谱仪(LA-ICP-MS)原位微量元素分析手段,结合机器学习方法,对浩布高闪锌矿微量元素组成特征、赋存机制以及矿床成因类型进行了探讨。LA-ICP-MS分析结果表明,浩布高矿床中闪锌矿以富集Fe、Mn、Co、Cu、Se、Ag、Cd、In、Sn等元素,贫Ni、Ga、Ge、As、Mo、Sb、Au、Tl、Pb、Bi等元素为特征。其中,Fe、Mn、In等元素主要以类质同象的方式替代Zn赋存于闪锌矿中,Cu、Ag、Sn等元素含量变化范围较大,可能部分以微粒包裹体的形式存在。In与Cu含量具有一定的正相关,推测In在闪锌矿中富集机理可能为Cu⁺+In³⁺↔2Zn²⁺。Cd与Fe含量呈一定的正相关性,而与Zn含量呈负相关性,这可能暗示在闪锌矿中Cd主要以类质同象的方式置换Zn元素而非Fe元素。通过穷举闪锌矿微量元素图解发现,即使得分最高的Co/Ag-Mn图解依然存在较大范围的重叠区域,因此不能简单地用闪锌矿微量元素二元图解来判别矿床类型。通过测试四种机器学习中经典的不同核函数的支持向量机算法,最终得出准确率为91.5%的高斯内核支持向量机闪锌矿成矿类型分类器,可以用于多种矿床类型闪锌矿的研究。浩布高矿床中闪锌矿微量元素组成明显不同于密西西比河谷型(MVT)、沉积喷流型(SEDEX)、火山块状硫化物型(VMS)和浅成低温热液型铅锌矿床,而与矽卡岩型接近。综合已有矿物学、年代学以及本研究获得的闪锌矿地球化学证据表明,浩布高应是一个典型的矽卡岩型铅锌矿床。

Geochemical characteristics and geological significance of beryl in different types of beryllium deposits.

Geochemical characteristics and geological significance of beryl in different types of beryllium deposits.

Diagenetic conditions and geological significance of weakly fractionation I-type granodiorite closely related to W-Mo mineralization in Zhuxiling, southern Anhui Province, China

Diagenetic conditions and geological significance of weakly fractionation I-type granodiorite closely related to W-Mo mineralization in Zhuxiling, southern Anhui Province, China

Enrichment characteristics and its geological significance of dispersed elements within sulfide minerals from the Ⅵ ore belt in the Maoping Pb-Zn deposit, Yunnan Province, China

Enrichment characteristics and its geological significance of dispersed elements within sulfide minerals from the Ⅵ ore belt in the Maoping Pb-Zn deposit, Yunnan Province, China

Formation water geochemistry and the petroleum geological significance in Yanchang Formation of Wuqi Oilfield, Ordos Basin, China

Formation water can evaluate the petroleum preservation conditions and thus can be used to identify hydrocarbon reservoirs. This paper analysed the formation water geochemistry and its relationship with the petroleum distribution in Yanchang Formation of Wuqi Oilfield, Ordos Basin. The formation water shows property of weak acid and high salinity. The ion concentrations are dominated by C1-, Na+, K+ and Ca2+. The CaCl2-type water is predominant. The chemical properties here indicate good sealing conditions for petroleum preservation. The high TDS value and the low (Na+ /C1-), (100 × SO42-/Cl- and ((CO32- + HCO3-/CA2+) ratios indicate better sealing condition for petroleum preservation. The formation water chemical geochemistry can provide predictions of oil-rich reservoirs. [Received: January 24, 2022, Accepted: June 04, 2022]

The Ni-Co occurrence modes and geological significance of the Xiarihamu Ni-Co sulfide deposit, western China

东昆仑造山带夏日哈木超大型镍钴硫化物矿床伴生钴资源,对其钴富集机制的认识离不开矿物中钴含量及其赋存状态方面的制约。本文采用场发射-扫描电子显微镜-能谱分析和电子探针对夏日哈木I号镁铁-超镁铁质岩体中不同类型的矿物进行了成矿元素含量测定及表征,在矿物层面探讨了钴含量变化和赋存状态。确认钴镍的赋存状态(含量)与矿物类型、岩浆结晶阶段(演化时间)有关:硫(砷)化物的钴含量高于硅酸盐造岩矿物,辉砷钴矿等砷化物钴独立矿物具有最高的钴含量。镁铁质岩浆硫不饱和时,早期结晶橄榄石中镍含量较高,中期结晶辉石岩的辉石晶体结构中的钴发生晶体化学分散;岩浆硫饱和-硫化物熔离过程中钴和镍优先进入硫化物熔体而富集,单硫化物固溶体(MSS)早期结晶的磁黄铁矿中钴含量大于镍含量,钴与镍含量正相关;MSS中期结晶的镍黄铁矿优先富集钴,钴与镍含量负相关,钴可能与镍类质同象替换进入镍黄铁矿而优先富集;MSS早期钴与砷形成辉砷钴矿等钴独立矿物,钴富集程度高、但总量有限。最后,本文认为硫化物熔离是夏日哈木矿床钴富集的主要机制。

Formation water geochemistry and the petroleum geological significance in Yanchang Formation of Wuqi oilfield, Ordos Basin, China

Formation water geochemistry and the petroleum geological significance in Yanchang Formation of Wuqi oilfield, Ordos Basin, China

Genesis and geological significance of sulfide bearing mafic enclaves and host syenite in Heishishan, East Kunlun: Evidence from geochronology, mineralogy, geochemistry and Sr-Nd-Hf isotopes

黑石山铜铅锌矿床位于东昆仑造山带中段的五龙沟地区，矿区内的石英二长岩-正长岩发育有暗色微粒包体，本研究在包体中发现了硫化物。锆石U-Pb定年显示，正长岩形成于239.4±1.0Ma，具有富Si和K，贫Mg、Cr、Ni，明显的Eu负异常，富集大离子亲石元素、亏损高场强元素，较为富集的Sr-Nd-Hf同位素特征。暗色微粒包体由斜长石和角闪石组成，可见角闪石堆晶，贫硅、富钙、铝、碱和铁，Mg^#值为38.37，具有明显的Eu负异常，轻重稀土分馏弱。结合宿主正长岩和暗色包体的矿物成分相似性和岩相学特征，本文认为暗色微粒包体与正长岩来自同一个岩浆房，属于同源岩浆包体，是岩浆房早期分离结晶相，被中酸性岩脉携带上升至正长岩熔体中，一起侵位至浅部地壳。综合岩石地球化学、同位素和矿物成分，本文认为正长岩是下地壳含水镁铁质岩石在压力较低条件下部分熔融的产物。暗色微粒包体中发育硫化物，且包体岩浆的硫含量远高于正长岩岩浆，指示岩浆房的早期分离结晶相带走了硫，使残余熔体贫硫。

Thin-section Petrography and Heavy Mineral Study of sandstones of the Barail Group of rocks occuring around Sonapur area of Jaintia Hills, Meghalaya, India

The study area represents a part of the South Shillong Shelf, Meghalaya, where sandstones belonging to the Barail Group (Eocene-Oligocene) are well exposed. Thin section petrography and heavy mineral investigations have been undertaken to assess the geological significance of the sandstones. Framework grains of the Barail sediments comprise of quartz (56.98 to 71.91%), feldspar (1.87 to 7.35%), mica (1.07 to 9.72%), lithic fragments (2.20 to 8.41%) and matrix (9.20 to 20.43%). The detrital composition of the sandstones comprises primarily of quartz grains, angular to sub-rounded, fine to medium grained and moderately sorted in nature. The sandstones are classified as subarkose, feldspathic graywacke and lithic graywacke. Provenance discrimination triangular plots of QFL and QmFLt reflect that the detritus were mostly derived from cratonic interior sources. The Diamond diagram indicates that the Barail sandstones were derived from middle and upper rank metamorphic source. Heavy mineral study of these sandstones indicates the presence of zircon, tourmaline, rutile, sillimanite, kyanite, staurolite, garnet, epidote, sphene, hypersthene, hornblende, chlorite, chloritoid, andalusite, apatite and opaque minerals. The percentages of most stable heavy minerals zircon, tourmaline and rutile vary from 6.11to 21.61, 2.60 to 6.56 and 2.42 to 7.57 respectively. The ZTR maturity index varies from 15.15 to 34.37, which reflects that the sandstones are mineralogically immature. The petrographic and heavy mineral study of the sandstones suggest that the detritus was probably derived from Shillong Massif where Precambrian metamorphic rocks of pelitic and arenaceous composition with plutonic bodies were exposed around the shelf margin. As the Shillong Massif comprises of Precambrian metamorphic rocks of pelitic and semitic (arenaceous) composition with intrusive plutonic bodies.

Seismic interpretation and geological evaluation of hydrocarbon source rocks in volcanic-rich continental lacustrine rift basins: A case study of the Lower Cretaceous Yingcheng Formation from the Changling Fault Depression in the Songliao Basin, NE China

The Lower Cretaceous Yingcheng Formation in the Changling Fault Depression in the Songliao Basin is composed of volcanic-rich continental lacustrine rift basin sediments. Its complex stratigraphic structure and the difficulty in predicting the hydrocarbon source rock distribution restrict the exploration and evaluation of deep hydrocarbons in this region. This paper uses seismic stratigraphy to divide the strata and interpret dark mudstone layers based on logging and seismic. These data are combined with geochemical test data from hydrocarbon source rocks to assess its quality and predict its distribution. This study indicates that the three types of unconformities identified divide the Yingcheng Formation into four sedimentary sequences. In the Yingcheng Formation depositional period, the number of grabens or half-grabens associated with the Changling Fault Depression decreased, the size of the rift basins increased, and the depositional center migrated to the north and west. During the depositional period of the First and Second Members, volcanic rocks were widely developed, and mud sediments were deposited between several small grabens or half-grabens. During the depositional period of the Third and fourth Members, the study area became a unified lacustrine rift basin with clearly defined geological signatures developed in each sedimentary sequence, which can be divided into three systems tracts. Mudstones in the Lake Transgressive Systems Tract are laterally continuous and widely distributed. The organic matter in these mudstones, with fair to good abundance levels, is predominantly type II2 and type III kerogen and all have reached mature to highly mature stage of thermal evolution, which are favorable hydrocarbon source rock layers. In plan view, the favorable hydrocarbon source rock zones are mostly formed in the Changling Sag, Dongling Structural Zone and Longfengshan Sag. This study offers guidance and direction for deep hydrocarbon exploration in the Changling Fault Depression, and also provides a reference for methods and ideas to predict hydrocarbon source rock distribution in other lacustrine rift basins.

A Review on Geological View of Svalbard with its Infrastructure and Strategies

Arctic Region (AR); Its role in global climate change, recently opened commercial sea routes, unexploited industrial resources, unique polar ecosystem and international geopolitical balance making it a strategic area that attracts the attention of many countries. In this aspect, the Arctic Council carries out various studies and international cooperation, especially interdisciplinary scientific research in the AR. Apart from the Council, many institutions, organizations and societies come to the AR to conduct scientific studies. When these studies examined from a geological point of view, it seen that they classified as glacial science, marine geology, geomorphology, microbial ecology, permafrost, biogeochemistry and geochemistry. Svalbard is geologically salient as well as being the place where most scientific studies are conducting in AR. In line with the geological significance of Svalbard, many institutions are engaged in educational studies, science strategies, international projects, etc. In this study, the geological structure, geological infrastructure and scientific strategy for geological researches of the Svalbard Region are examined. Moreover, projects that can be done within the scope of scientific researches of Turkey in AR, are evaluated as a recommendation.

Geochronology, geochemistry, and Sr–Nd–Hf isotopes of the Cretaceous igneous rocks in the Zhilingtou area, SE China, and their geological significance

The Zhilingtou deposit is one of the typical porphyry Mo deposits in South China. Disseminated and veinlet Mo ores occur in the roof pendant of the granite porphyry or the contact between the granite porphyry and the Badu Group gneisses, and some orebodies are cut by adamellite dikes. Here we present zircon LA–ICP–MS U–Pb dating yielding crystallization ages of 97 ± 1 Ma for the adamellite and 110 ± 1 Ma for the graniteporphyry. The adamellite and granite porphyry are metaluminous-peraluminous and belong to the high-K calc-alkaline-shoshonite type. They are characterized by high K2O, K2O + Na2O, FeOT, FeOT/(FeOT + MgO) and zircon saturation temperatures (784–817 °C); low MgO, TiO2, P2O5, Sr/Y and La/Yb values; enrichment in trace elements Rb, Th, U, La, Ce and other large ion lithophile elements; and depletion in Ti, Nb and P and other high field strength elements, revealing a highly fractionated A2-type affinity, formed in an extensional tectonic setting. The zircon εHf(t) values of the adamellite and granite porphyry range from −6.3 to −3.2 and from −10.0 to −4.1, respectively, with two-stage Hf model ages (TDM2 (Hf)) of 1559–1367 Ma and 1802–1430 Ma, respectively. The εNd(t) values of the adamellite and granite porphyry range from −19.0 to −11.5 and from −7.5 to −6.2, respectively, with two-stage Nd model ages (TDM2 (Nd)) of 2435–1835 Ma and 1522–1413, respectively, suggesting that they had mixed sources and were mainly formed by partial melting of a late Paleoproterozoic basement in the lower crust. In combination with previous studies, it can be concluded that after the Early Cretaceous, the subduction orientation of the Izanagi plate changed from oblique to parallel with respect to the continental margin, the slab rollback resulted in large-scale lithospheric extension and thinning, asthenospheric upwelling, and the basaltic magma underwent underplating and induced crustal melting, and finally formed the A-type granitic intrusions and related Mo mineralization systems.

Zircon SHRIMP U–Pb geochronology, geochemistry, and geological significance of dacite in the Zhesang gold district, southeast Yunnan Province, China

Zircon SHRIMP U–Pb geochronology, geochemistry, and geological significance of dacite in the Zhesang gold district, southeast Yunnan Province, China