Table of Content

20 October 2018, Volume 24 Issue 5

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Features of Clay Minerals in the Middle Jurassic Zhiluo Formation Sandstones of the Nalinggou Area in the Ordos Basin and A Preliminary Comparison with Adjacent Areas

ZHAO Hualei, CHEN Lulu, FENG Xiaoxi, LI Jianguo, CHEN Yin, WANG Gui

2018, 24(5):  627. 

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The Nalinggou uranium deposit is located in the northeastern Ordos Basin and the U-bearing rock series occur in the
Middle Jurassic Zhiluo Formation. In this paper, method of microscopic identification, scanning electron microscopy and X-ray
diffraction were used to systematically observe and study the microscopic characteristics, composition and content of clay minerals
in the Zhiluo Formation sandstones of the Nalinggou area. Then, characteristics of the clay minerals were discussed in detail and
compared preliminariy with those of the adjacent Yili and Erlian basins. Results show that the clay minerals are mainly smectites,
followed by kaolinites, chlorites and illites. There is a mutual transformation between smectites and kaolinites, while some chlorites
are transformed from smectites and kaolinites. In contrast, smectites did not spontaneously transform to illites during the diagenesis.
The total amount of clay minerals in sandstones is relatively high. Compared with those in the Yili Basin, the sandstones in the study
area are rich in smectites, with less content of kaolinites, and have a strong adsorption capacity caused by clay minerals. During the
diagenesis, the adsorption of clay minerals led to a large amount of pre-enrichment of uranium, which is an important prerequisite for
the formation of many uranium deposits and even super-large uranium deposits in the northeastern Ordos Basin.

Caledonian Quartz Vein Type Gold Mineralization in the Dayaoshan Area,Guangxi: Constraint from the Muscovite 39Ar/40Ar Dating in the Shangmushui Gold Deposit

LI Zhongyang, DANG Yuan, LE Xingwen

2018, 24(5):  637. 

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Quartz vein type gold deposit is one of the most important gold deposit types in the Dayaoshan area, Guangxi Province.
However, there has been no high precision age data to constrain its mineralization epoch. This paper firstly used muscovite
39Ar/40Ar dating to constrain the age of Shangmushui quartz vein type gold deposit in the southern Dayaoshan area from Cangwu
County, Guangxi Province. The study yielded a plateau age of 432.6 ± 3.2 Ma, an isochron age of 428.2 ± 7.2 Ma, and an inverseisochron
age of 425.3 ± 6.6 Ma, indicating its mineralization epoch is Caledonian. These new data further demonstrate that the
Caledonian is the main mineralogenetic epoch in the Gulong-Xiaying ore-forming area from the southern Dayaoshan area.
Except for the Caledonian granitoids related porphyry-skarn tungsten polymetallic mineralization, there are quartz vein type
gold deposits. Meanwhile, the timing of Liucen-Taohua-Gupao gold ore field along the regional Dali fault is not clear and the
oreforming age will need to be constrained by high precision clating data in the future.

Mineralogical Behavior and Metallogenic Process of Sn in the Xianghualing Skarn, Hunan Province

YU Xuege, RAO Can, WANG-WU Mengyu, LIN Xiaoqing, QIN Lixi

2018, 24(5):  645. 

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Xianghualing tin deposit is one of the most important tin-polymetallic deposits in Nanling Region, and hosts abundant
Sn-bearing minerals. In this paper, the mineralogical characteristics of Sn-bearing minerals from the Xianghualing skarn were
systematically analyzed by electron microprobe technology, in combination with microscopic and field observations, with the aims
to reveal metallogenic processes, fluids features, and origin of Sn. The results of this study show that (1) Sn-bearing minerals in
the Xianghualing skarn include Sn minerals (cassiterite, nigerite, mengxianminite etc.) and Sn-rich minerals (pargasite, spinel,
prehnite, taaffeite etc.); (2) Three stages of Sn mineralization were distinguished: during the early skarn stages, Sn entered into
the structures of spinel, amphibole, and other rock-forming minerals, leading to the formation of Sn-rich minerals; Sn minerals
(cassiterite, nigerite, mengxianminite etc.) gradually crystallized during the oxidation stages, and in the hydrothermal stages early
Sn-bearing minerals experienced hydrothermal alteration with local precipitation of cassiterite, and/or the formation of minerals
with Sn-rich rims by Sn-rich fluids; (3) hydrothermal fluids are enriched in F, CO2 and Li, which controlled the processes of
enrichment, transport, and crystallization of Sn, and (4) Sn in the Xianghualing skarn was fundamentally derived from the ambient
strata, and the metallogenic processes of Sn reflect a geochemical circulation of Sn in Earth Crust.

Detrital Zircon Components of Sinian-Cambrian Sedimentary Rocks in SE Yunnan: Constrain on the Boundary between Yangtze and Cathaysia Blocks

ZHU Guanglei, YU Jinhai, SHEN Linwei, ZHOU Xueyao

2018, 24(5):  658. 

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The basement component of the Pingbian area, SE Yunnan, has not been well studied before. The tectonic attribution
of this area is important for constraining the western boundary between the Yangtze and Cathaysia blocks. U-Pb-Hf isotopic
compositions of detrital zircons from the Sinian-Cambrian sedimentary rocks in the Pingbian area are used to provide new
evidence for determining this boundary. Zircon U-Pb dating results indicate that two sedimentary rocks from the Sinian and
Cambrian strata share the similar detritus components. Most of them were formed in Neoproterozoic (700-937 Ma) with an
age peak at ~815 Ma. Both sedimentary rocks also contain a small amount of Paleo- to Mesoproterozoic detritus. Six youngest
concordant zircons have ages of 696-761 Ma, suggesting that the formation age of the Pingbian Group sedimentary rocks probably
formed in the Late Neoproterozoic, equivalent to Sinian time. The Pingbian Group sample shows the unimodal age spectrum
with dominant Neoproterozoic detrital zircons, similar to those sedimentary rocks in the southern and western Yangtze Block,
but different from the sedimentary rocks in the Cathaysia and Indochina blocks. Hf isotopic characteristics of detrital zircons
also suggest the affinity of the Pingbian Group with the Yangtze Block (especially the western margin). According to these data
and other evidence, we believe that the Pingbian area in SE Yunnan Province belongs to the Yangtze Block. Thus, the western
boundary between the Yangtze and Cathaysia blocks should be located at south or southeast of the study area, rather than the
Shizong-Mile-Luodian Fault. The detrital zircon age distribution patterns also indicate that the Sinian Pingbian Group was
deposited in the back-arc basin, implying that Neoproterozoic subduction along the southwestern margin of the Yangtze Block
lasted until ~752 Ma.

Comparative Study of the Adsorption of L-lysine on the Different Clay Minerals

KAI Wei, CAI Yuanfeng, CAI Jingong, JI Junfeng

2018, 24(5):  671. 

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Adsorption of organic matters on clay minerals is a ubiquitous phenomenon. In order to better understand such a
reaction, adsorption behavior of lysine onto clay minerals including saponite, montmorillonite, kaolinite, chlorite and illite was
investigated and characterized by powder X-ray (XRD), Fourier-transform Infrared Spectroscopy (FTIR) and Thermal Gravimetric
Analysis (TGA). The results showed that the adsorption isotherms of lysine on clays were well fitted using the Freundlich equation
(R2=0.98-0.83) and the adsorption capacity followed the order: saponite>montmorillonite>chlorite>kaolinite>illite. XRD results
indicated that the adsorption of lysine on saponite and montmorillonite ocurred mainly in the interlayer regions, while lysine was
mainly present on the surface of chlorite, kaolinite and illite. Furthermore, FTIR and TG results showed adsorption of lysine in the
interlay region might take place via replacement of interlayer water and subsequent formation of hydrogen bond with O-Si-Si(IVAl).
This work will contribute to understanding of adsorption behavior and mechanisms of organic matters on clay minerals.

Genesis of the Albian Dolomite in Levant Basin, East Mediterranean: A Case Study of the Givat Ye’arim Formation and Soreq Formation near Jerusalem, Israel

WANG Xiaomin, HU Zhongya, LI Weiqiang

2018, 24(5):  681. 

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The “dolomite problem” is one of the long-lasting problems in sedimentology. Magnesium is a major element in
dolomite, and its isotopic compositions may be used to infer the dolomitization processes and sedimentary environments. In this
study, we investigated the Mg isotope compositions of dolostones of the Albian Givat Ye’arim Formation and Soreq Formation of
Albian from a section near Jerusalem, Israel. The carbonates are mainly composed of subhedreal to euhedral micritic dolomite
without notable post-depositional diagenetic alterations. Carbon and strontium isotope compositions of the dolomite are consistent
with the Albian seawater, suggesting that the dolomitizing fluid was sourced from the contemporaneous seawater. δ26Mg values
of dolomite cluster around -2.0‰ and do not show a clear correlation with depth. Combining Mg isotope and C-Sr isotope
compositions of dolomite, it is suggested that the Mg supply from seawater for dolomitization was abundant, leading to Mg isotope
equilibrium between seawater and dolomite. The rhythmic fluctuations in Na, Rb and ΣREE contents in the dolomite sequence
indicate responses of marine environments in a semi-closed basin to variations in regional paleo-climates and paleo-environments.
By contrast, the relatively homogeneous dolomite δ26Mg values across the sedimentary beddings imply that the regional climate and
environment changes had limited impacts on Mg isotope compositions of seawater in local basins. Hence, for massive dolomite that
was deposited in partly restricted basins, their δ26Mg values likely still trace the Mg isotope composition of seawater in open oceans.

Chemical Composition of Biotite from the Gejiu Granite, Yunnan Province: Implication for Petrogenesis and Mineralization of Kafang Tin Polymetallic Deposit

MA Lianhua， CAI Yongfeng， LIU Xijun， XU Jifeng， ZHOU Yun， SU Xiaoqian

2018, 24(5):  692. 

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Mineralization of the Kafang tin polymetallic deposit is closely related to granitic magmatism. The chemical composition
of biotite, which is the most common mafic mineral in granite, has been used to reveal petrogenesis and mineralization. Detailed
chemical compositions of biotite from the Kafang granite of the Gejiu tin orefield, a famous tin polymetallic deposit in China, are
presented in this study. Results of electron microprobe analyzer (EMPA) indicate that the biotite has high SiO2, FeOT, Al2O3, K2O
and TiO2, and low MgO, CaO, Na2O and MnO contents, with Fe/(Fe+Mg) values of 0.67-0.83, resembling those of iron biotite.
These characteristics suggest that their host granites were mainly originated from partial melting of crustal materials. Calculation
results of biotite thermometers, Al-in-biotite barometer and oxygen fugacity estimation suggest that they have high crystallization
temperatures of 500-708℃, crystallization pressure of 202-538 MPa with corresponding crystallization depth of 7.64-20.35 km,
and oxygen fugacities from high to low. Integrated with regional geological data, we propose that high iron indexes and from high
to low oxygen fugacities of the biotite from Kafang granite are favored for Sn mineralization. These characteristics could be key
tracers for Sn exploration.

Study of the Deep Electrical Structure in the Eastern Margin of the Qingzang Plateau

ZHAO Lifang, SHU Liangshu, YU Changqing, WANG Yang, QU Chen, MA Xuxuan

2018, 24(5):  702. 

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By the study of the measured data of the magnetotelluric sounding in the eastern margin of the Qingzang Plateau, the
relationships among the deep structure, the high-conductivity layer in the crust, the electrical structure and mineral resources
have been studied based on the regional geological, gravitic, magnetic, magnetotelluric and seismic data. Our results suggest that
the Moho plane derived from gravimetric calculation is an interface made up of many high and low resistance layers, and the intra-crustal
high-conduct layers occur mainly near the Moho plane. The resistivity change interface exists at about 15 km depth, which should
be a boundary between the upper and lower crustal parts. At the same time, the electrical properties and Vs indicate that the crust
thickness has been reduced at about 20 km in the mantle plume developed area. Deep faults, such as the Jinshajiang-Honghe
fault and the Xianshuihe fault, have reached the Moho plane and become the boundaries of blocks or metallogenic zones, controlling
the distribution of high-conductivity bodies in the continental blocks. The formation of the high conduct layer of the Gongga crusmantle
and the relationship between the mantle plume and the mineral resources in the study area are also discussed.

Crustal Structure of SE Tibet Plateau by Receiver Function

CAO Xu, MI Ning, YU Dayong, WANG Liangshu, XU Mingjie, LI Hua, HUANG Zhouchuan, WANG Pan

2018, 24(5):  715. 

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As the front region of plate collision, the southern Tibet has always been the hotspot in geoscience research. To
reveal the features of the crustal structure of collision frontal zone, we used 2487 tele-seismic records recorded by 38 broadband
stations in the southeast Tibet. Then we calculated the crustal thickness and Poisson’s ratio of this area by CCP stacking and H-κ
stacking. The results of the crustal thickness obtained by the two methods are in good agreement, and the crustal thickness in the
southeastern Tibet has obvious difference in east-west and north-south. The depth of Moho varies greatly in the Himalaya tectonic
zone, ranging from 65 to 80 km. The depth of Moho in Lhasa block ranges from 72 km to 80 km. The crustal thickness on both
sides of the Yarlung Zangbo suture has been abruptly changed. The difference in thickness between the north side and the south
side of the suture is about 8 km. The average Poisson ratio in the study area is 0.24, which is consistent with the feather that the
Poisson ratio in most orogenic belts is low. A strong transition interface exists widely in the middle and lower crust of the study
area, the interface may be the upper interface of the high-velocity layer in the middle-lower crust, with a depth of 40-70 km. It
indicated that deep melting or partial melting occurred in the crust, leading to gravitational differentiation and forming a highvelocity
thin layer in the middle-lower crust.

Structural Characteristics and Activity Rules of Faults in the Cenozoic Faulted-Basins in the Lower Yangtze Region

XU Xi, SUN Lianpu, XIAO Mengchu, LI Xiao, ZHU Xiaoying, GAO Shunli

2018, 24(5):  723. 

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The Cenozoic sedimentary basins cluster in the onshore and offshore Lower Yangtze region are representative of the
petroliferous province in eastern China, in which the characteristics and activity rules of faults are key foundation for the study
of petroleum exploration. In this study, we address the deformation characteristics and activity rules of fault by using structural
fault analyses based on high-coverage seismic prospecting data. Results show that the faults can be classified into three types
based on the style of fault assemblage, i. e., extended, strike-slipped and extruded-reversed. According to the characteristics of
fault activity, the basinal faults can be divided mainly into two structural systems, i. e., extensional and combined extensional with
strike-slip. Tectonically, the basinal faults were prominently controlled by the dextral deformation of the Tan-Lu fault, and their
structural activities are related to the reqional location and the distance to the Tan-Lu fault. The basinal faults are characterized
by apparent division between the east and the west and unique in the central. The varied stress field of the Lower Yangtze region
during the Cenozoic controls the opening and closing of the fault as oil and gas migration pathway. This is an important criteria for
the evaluation of oil and gas resources.

Modeling Multiphase Flow and Transport of Gas Hydrate Zones: A Case Study from the Shenhu Area of the South China Sea

YE Hong, YANG Tao, ZHU Guorong, JIANG Shaoyong

2018, 24(5):  734. 

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Gas hydrates are one of the significant offshore petroleum resources. The exploration of hydrates using combined
porewater geochemistry and fluid reaction-transport modelling has become an important proxy in researches of recent years.
Based on the data of GMGS-1 drilling project from the Shenhu area of the South China Sea, the advection velocity of porewater
during the Holocene was fitted by the molar ratio of bromine to iodine, and a two-stage non-steady state multiphase fluid transport
model of the gas hydrate zone was constructed. We found that the hydrate accumulation in the study area, i.e. Site SH7, was in
decline since the Pleistocene. Through sensitivity analysis of model parameters, it was learned that the parameter weights affecting
the output were sediment porosity, organic matter content and sediment burial rate in descending order. Further numerical
analysis shows that in the hydrate accumulation system, hydrate saturation is proportional to organic matter content, but shows
a non-monotonic dependence on other main parameters. Besides, it is the external methane from deep below dominates the
methane source in the hydrate stability zone. The multiphase fluid transport model of this study provides theoretical basis for the
exploration of hydrate resources.

Lithofacies and Palaeogeography of the Early-Middle Ordovician in the Western Ordos Basin

WU Dongxu, ZHOU Jingao, WU Xingning, DING Zhenchun, YU Zhou, WANG Shaoyi

2018, 24(5):  747. 

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The lithofacies and paleogeography of the Early-Middle Ordovician in the western Ordos Basin were reconstructed
based on the stratigraphic comparison and core and thin section observation of many exploration wells, combined with
measurements of multiple outcrops. The methodology is the single factor analysis and multifactor comprehensive mapping. Results
of characterization of stratigraphic thickness show that the Early-Middle Ordovician in the western basin has a palaeogeographic
pattern of three oldlands, one depression and one trough, i. e., the Alxa oldland, Iran oldland, Qingyang oldland, Dingbei
depression and Helan sea trough. Field measurement of lithologic profiles and comparison with drilling data show that along with
the extension of the Helan Trough and the extrusion to the North China plate eastward, the western basin experienced multiple
tectono-sedimentary stages. These include the successively sedimentation of carbonate rocks in the Sandaokan and Zhuozishan
periods, weakly striped platform deposition in the Kelimoli period, the slope and basin sediments in the Wulalike period.
Accordingly, carbonate reservoirs were developed, including the platform shoal reservoirs represented by the Zhuozishan Group,
the reef shoal reservoirs in the weakly striped platform margin represented by the Kelimoli Group. They are generally dolomitized
In the Early-Middle Ordovician, large amounts of deep-sea turbidites were developed in the study area, forming on extremely
thick flyschoid sedimentary formation, which has few hydrocarbon generation abilities. Only the graptolite-bearing shales that
formed in the Upper Ordovician Wulalike and Pingliang formations have some hydrocarbon generation abilities..

Cenozoic Deformation Characteristics of the Xianshuiquan Anticline in the Northwestern Qaidam Basin and Its Significance

HUANG Kai， CHEN Liqi， XIAO Ancheng， SHEN Ya， WU Lei

2018, 24(5):  761. 

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The Cenozoic deformation in the NW Qaidam Basin is controlled by both the NE-directed thrusting and NEE-directed
sinistral strike-slipping. In this paper, we analyze the characteristics and mechanism of the Cenozoic deformation across the
Xianshuiquan anticline in the northern end of the Yinxiong Range in the western Qaidam Basin based on field investigation,
borehole logging, and 3D high-resolution seismic data. The results show that the Xianshuiquan anticline is largely controlled by
NEE-directed basement-involved dextral thrust faults since the late Miocene with intense deformation occurring in Pleistocene.
According to the different deformation patterns, we divide the Xianshuiquan anticline into the northern and the southern parts.
The southern part is slightly influenced by the Altyn Tagh Fault system and is characterized by the development of NNW-trending
secondary anticlines and NW-trending back-thrusts with small amount of horizontal shortening. The northern part is greatly
affected by the Altyn Tagh Fault system and is characterized by NWW-trending sub-anticlines and back-thrusts with much larger
amount of shortening. Our results support that the Qaidam basin is a compression-dominated basin, and the influence of the
sinistral strike-slip Altyn Tagh Fault system on its deformation is only confined within a limited area in the Cenozoic.

On Localized Ensemble Kalman Filter to Calibrate Heterogeneous Hydraulic Conductivity Field by Assimilating Hydraulic Head and Solute Concentration Observations

CAO Shaohua, CUI Kaipeng, JIANG Jianguo, WU Jichun

2018, 24(5):  769. 

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Localized Ensemble Kalman Filter (EnKF) is used to overcome the defect of EnKF that the accuracy of parameter estimation
is low when a small ensemble is used. There are numerous study on using EnKF to estimate heterogeneous hydraulic conductivity by
assimilating hydraulic head observations. In practice, solute concentration data are easy to collect. Cui (2013) used localized EnKF to
estimate heterogeneous hydraulic conductivity field in a 2-D confined aquifer by assimilating the hydraulic head and solute concentration
observations simultaneously, but the result was not satisfying for some unknown reason. In this study we use two solute injection wells
(instead of one solute injection well) so that more effective solute concentration data can be collected during the assimilation process.
In addition, we compare the results with the fields estimated based only on head and solute transport data, respectively. It is found that:
(1) Localized EnKF yields more accurate hydraulic conductivity estimates than EnKF; (2) assimilating hydraulic head observations
and solute concentration observations together results in better estimates than assimilating any single type of observations. In addition,
hydraulic conductivity estimates in the reach of plumes can be well estimated by using solute concentration or head observations.

Experimental Study on Distributed Monitoring of Ground Collapse Deformation Based on BOFDA

LU Yi，YU Jun，GONG Xulong，SHI Bin，WANG Baojun，JI Junfeng

2018, 24(5):  778. 

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Ground collapse is a geological disaster, which will become an urgent problem in urban development. The distributed
monitoring model test of ground collapse was carried out based on Brillouin Optical Frequency Domain Analysis (BOFDA)
technology in this study. A self-made model was used to test the deformation of ground collapse with different types and
thicknesses of soil conditions. The results indicated that the distributed optical fiber sensing technology based on BOFDA can
capture the occurrence and development process of ground collapse and reflect the deformation law of the soil effectively. The
research results provide a reference for popularization and application of this technique in deformation monitoring of ground
collapse.