Table of Content

20 June 2019, Volume 25 Issue 3

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Mineralogical Behavior of Lithium and Its Implications from the Xiekusite Pegmatite, Altay, Xinjiang

XU Yaochen，LU Huan，RAOCan

2019, 25(3):  321. 

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Xiekusite pegmatite, a typical Li-Cs-Ta(LCT) pegmatite, is located in the Koktokay county of Altay, Xinjiang, and hosts a
large amounts of lithium minerals of phosphate and silicate. In this paper, in combination with field observations, the mineralogical
behavior of Li from the Xiekusite pegmatite has been studied for crystallization evolution and hydrothermal alteration of Li minerals
during magmatic to hydrothermal stages by electron micro-probe and X-ray diffraction analyses. The results show that (1) Li minerals
from the Xiekusite pegmatite crystallized through two stages, spodumene, montebrasite and lithiophylite formed during the magmatic
stage; while elbaite, polylithionite and trilithionite crystallized from the magmatic-hydrothermal transition stage to hydrothermal stage.
(2) The rock-inclusions of montebrasite-lithiophylite association reflect an immiscibility mechanism between Li phosphate melt and Li
silicate melt in the Xiekusite pegmatite. (3) Lithiophyllite was altered to a series of minerals which have similar structures but different
colors (from light yellowish to deep red ), suggestive of the oxidation and Li-leaching processes of lithiophyllite. (4) Li was leached into
fluids by hydrothermal alteration of Li minerals such as spodumene, montebrasite and lithiophylite, and secondary Li-bearing minerals
crystallized from the Li-rich fluids, these processes reflect the geochemical cycle of Li in the Xiekusite pegmatite.

A Comparative Study on Microtopography of Jarosite Formed in Different Conditions

CAOLina，CHENBinghui，GOUXiying，ZOU Qi

2019, 25(3):  333. 

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Jarosite is a very common secondary mineral in acid mine drainage (AMD). It can absorb effectively heavy metallic elements
such as Pb, Zn, Gd, As in AMD. The jarosite formed under different conditions is of diverse microtopography and different adsorption
capacities to heavy metallic ions. In this paper, jarosite was synthesized by chemical and microbiological methods, respectively, and
the samples of sediments with jarosite-bearing secondary minerals were collected form the AMD of Dabaoshan Mine in the north
Guangdong Province. The jarosite formed under different conditions was identified by using SEM and XRD, its microtopographic
characteristics were observed, and the synthesis conditions of jarosite were investigated. The results show that the range of pH values in
which jarosite can be chemically synthesized is approximately 2.0-2.5 at room temperatures. The crystal size of the synthetic jarosite is
about 2-10 μm and the crystalline form is plate-like. Jarosite can also be chemically synthesized at 65℃ with a wider range of pH
values between 2.0-3.0, but the crystalline form is relatively poor. Jarosite can be synthesized by microbial method in a relatively large
range of pH values between 2.0-5.0, which has nearly perfect rhombohedron-shape crystalline form and relatively uniform sizes about
2-4 μm. Jarosite discovered in sediments of AMD occurs in a pH value ranging from 2.5 to 3.5. It is of relatively perfect rhombohedron-shape crystal and the single crystal size is mostly in 1-2 μm. According to the formation conditions and microtopographic
characteristics, the jarosite formed in AMD is probably of microbial origin.

A Preliminary Study on Metallogenic Age and Genesis of Longping Fluorite Deposit in Southern Jiangxi Province: Evidence from Sm-Nd Isochron Dating of Fluorite and Electron Probe of Biotite

YANG Shiwen，FENG Chengyou，LOU Fasheng，ZHANG Fangrong，HE Bin，CAOYuanbing

2019, 25(3):  341. 

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The Longping fluorite deposit is the large single fluorite deposit discovered in southern Jiangxi Province, China. The ore
body occurs in the NE-trending silicified fractured zone within the outer contact zone of the Yongfeng complex. In this paper, for the
first time, the Sm-Nd Isochronal method is used to estimate the age of Longping fluorite deposit, and rare earth elements and the
mineral composition of biotite in the Yongfeng complex are systematically studied. The ore-forming age of the Longping fluorite deposit
is 158 ± 3Ma, which is consistent with the diagenetic age of the Yongfeng complex, indicating that the Yanshanian fluorite
mineralization in this area was closely related to the Late Jurassic magmatism. The fluorite in the Longping fluorite deposit is enriched
in light rare earth elements, and the heavy rare earth elements remain relatively unchanged, with weak Ce positive anomalies (δCe=
1.08-1.11, average 1.09) and weak Eu negative anomalies (δEu=0.91-0.98, average 0.95), indicating that the ore-forming fluids of the
fluorite deposit experienced relatively high temperature. The results of electron probe analysis of biotite show that the Yongfeng complex was formed in a relatively high temperature, low pressure, and high oxygen fugacity environment. The magma originated from
the ancient crustal materials and the hydrothermal fluid was rich in F and other volatiles after the magma phase. The Longping fluorite
deposit may have mineralized in the Late Jurassic, and the genetic type is hydrothermal filling after the magmatism

Geochemical Migration Characteristics of Alteration of Pyritized Rocks and Their Genetic Relationship with Pyritization in the Zhangmajing Uranium-Molybdenum Deposit in Northern Hebei Province, China

SONGKai，WUJianhua，GUOHengfei，GUOGuolin

2019, 25(3):  352. 

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The Zhangmajing uranium deposit is the largest volcanic-related hydrothermal uranium deposit in northern China, which
wall-rock alteration was widely developed. The distribution of pyrite mineralization in this deposit is relatively limited, but closely 
related to mineralization. In order to study the relationship between pyrite transformation and uranium mineralization, molybdenum
mineralization, the main trace element analysis of the pyrite-altered rock in Zhangmajing was carried out. This paper used the mass
balance migration method using Yb as the inactive component to calculate its component migration with the Grant formula. The
geochemical characteristics of the rocks showed that the content of TFeO in pyrite altered rock was extremely high, ranging from
11.24% to 24.57% (average 18.45%), of which Fe2O3 content was 10.78%~25.25% (average 18.64%), FeO content was 1.43%~1.90%
(average 1.69% ). The average Fe2O3/FeO ratio was 10.99, which might be affected by subsequent oxidation. The slope of the
iso-concentration line of the pyrite-altered rock was less than 1 in the Isocon diagram, indicating that the whole component had been
taken in. The taken-in component was mainly the large amount of TFeO (131 times), ore-forming element including Mo (884 times), Pb
(11 times), U (4.9 times), V (2.8 times), Ta (0.44 times), Cu (0.64 times), and alkali metal Na2O (0.45 times), and Cd (424 times), Bi (13
times), etc. In addition, the alkali metal Li (-0.73), K2O (-0.17), ore-forming elements Zn (-0.38), Cr (-0.37), and Eu (-0.58), Sc
(-0.25) and other components were taken out. Among them, SiO2 was slightly reduced (-0.03), and the taken-in Mo content was much
higher than U which had relatively consistent migration characteristics with those of molybdenum ore. It could be concluded that t
pyrite altered rocks were closely molybdenum mineralization.

Zircon U-Pb Chronology and Hf Isotopic Compositions of the Early Permian Bimodal Volcanic Rocks from Wulang Formation in Jiamante Area of Western Tianshan，Xinjiang

CHENBangxue，XU Shengli，ZHOUNengwu，BAI Quanjin，HUANGJihan，ZHENG Yong

2019, 25(3):  364. 

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The basic and acidic volcanic rocks with SiO2 contents of 41.89%-52.75% and 74.79%-78.51%, respectively, are closely
associated in time and space in the area of Jiamante, western Tianshan Mountains. These volcanic rock associations show distinct
“Daly gap”, thus can be ascribed to the typical bimodal volcanic assemblage. The basic units can be grouped into alkaline series,
whereas the acidic units are calc-alkaline series. LA-ICP-MS zircon U-Pb dating and Hf isotopic analysis for rhyolites show that their
formation age is (294.2±0.8) Ma, indicating that they were formed in Early Permian. The volcanic rocks have positive εHf(t) values (8.0-
17.1), and young two-stage model ages with an average of 468 Ma. By integration of the geochemical characteristics and genetic types, it
is shown that the bimodal volcanic rocks in the Jiamante area can not be produced by differentiation from the same magma chamber.
Rather, they were likely originated from different sources. Among them, the basalt was originated from partial melting of the enriched
garnet peridotite induced by the phase transition from spinel peridotite to garnet peridotite, and rhyolite is generated by partial melting
of juvenile crust resulted from underplating of depleted mantle. Both the basic and acidic volcanic rocks were formed in an intraplate
extension environment. In combination with analysis of the regional tectonic evolution, it is suggested that the western Tianshan
Mountains were entered an extensional tectonic setting since the Early Permian.

Geological Characteristics and Paleoenvironmental Significance of the Paleogene Lacustrine Dolomite in the Beitang Sag, Bohai Bay Basin

LIN Chunming，WANG Bingjie，ZHANG Xia，ZHANG Ni，JIANG Kaixi，HUANG Shuya，CAI Mingjun

2019, 25(3):  377. 

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A special type of lacustrine dolomite reservoir was discovered in the Member 3 of Paleogene Shahejie Formation in the
Beitang sag, Bohai Bay Basin. The main rock types and mineral characteristics of the dolomites have been studied in detail by a vast
amount of data from core drilling, paleontology, rock thin section, scanning electron microscope, and electron microprobe. The
generation environments of the dolomites were debated by the X-ray diffraction data, major and trace element geochemistry. The
dolomites in the Beitang sag are usually bedded or laminated with mud or analcime, and the mineral components are mainly dolomite,
analcime, and clay minerals. The paleosalinity, paleotemperature, paleo-water depth, and redox conditions of the depositional
environments of the lacustrine dolomites were discussed carefully. We inferred the dolomites were deposited in the lacustrine bay with
a relatively high salinity, high temperature and high PH of the water column. The salinity of the lake increased during the seawater
intrusion, providing favorable physical and chemical conditions, subsequently promoted the dolomite formation.

Sand-body Distribution and Superposed Patterns of Alluvial Deposits in the Middle Jurassic in the Piedmont Zone of the Longmen Mountain Trust Belt

YU Haiyue，LIU Junlong，HAO Yunqing，SUN Wei，LIU Ling

2019, 25(3):  389. 

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The Middle Jurassic Shaximiao Formation in the piedmont zone of the Longmen Mountain Trust Belt (LMTB) consists of a
set of alluvial deposits, including alluvial fan and braided river delta. Based on the theory of high-resolution sequence stratigraphy, we
studied sand-body types of alluvial deposits in the piedmont zone by a comprehensive analysis of outcrop profiles, seismic section,
seismic amplitude image, core, and drilling data, summarized its vertical stacking patterns as well as horizontal distribution
characteristics. The results show that channel and sheet-like bar constitute the main sand-body types and channels are generally well
developed; Provenance and lake level changes are two important factors of sand-body distribution. Provenances affect sand-body
distribution of channels and lake level changes affect sand-body distribution of sheet-like bar and physical property of channels; four
types of sand-body superimposed patterns of different origins were classified, i.e., superimposed glutenite-body of channels in the
ultra-low accommodation, superimposed sand-body of channels in the low accommodation, superimposed sand-body of channels in the
high accommodation, and superimposed sand-body of channels and sheet-like bars in the high accommodation, respectively.

Palaeoclimate Changes Revealed by Sedimentary Records of the Upper Permian-Lower Triassic Strata in Yiyang Area, Western Henan Province, China

XING Zhifeng，LIN Jia，ZHOUHu，LI Da，QI Yongan，ZHENG Wei

2019, 25(3):  401. 

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The Yiyang area during the late Permian-early Triassic Boundary (PTB) was located in the southern margin of the North
China Craton in the lower latitudes of eastern Tethys. A set of continental clastic lithofacies was developed in this area and is ideal for
studying the paleoenvironment and paleoclimatic changes of the late Permain-early Triassic. This paper is based on previous research
and field observations to study the sedimentary characteristics in Yiyang area by investigating the lithology, sedimentology and
paleobiology. A lacustrine-fluvial sedimentary environment is identified and the paleogeography of Yiyang area is reconstructed. The
overall climate conditions during this period were hot-semiarid and extreme drought occurred at the end of the Changsingian and the
early Olenekian. The periodic (seasonal) climate could be controlled by Pangean Megamonsoon. The evolution of paleoclimate and
paleoenvironment may have played an important role in the end-Permian massive extinction and inhibited Triassic biotic recovery.

Discovery of Contourite and Its Significance in Qiongzhusi Formation of Meishucun Section, Central Yunnan Province, China

LI Xiangdong，CHENHaiyan

2019, 25(3):  412. 

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Although Qiongzhusi Formation of Cambrian is one of the most important shale gas exploration targets in South China and
the host rock of Chengjiang Fauna, studies of its sedimentary environments and processes are still inadequate. This study is focused on
the Meishucun Section of Kunyang in central Yunnan Province, where palaeocurrents with directional sedimentary structures are
analyzed and the extensive stripped-and-banded structures in Qiongzhusi Formation are studied based on detailed field observations.
The results show that (1) the palaeocurrent angles between cross-beddings and small flutes are from 43°to 108°, with distribution
mainly between 50° and 79°, and the average angle in the same thin-bedded siltstone is 50°, greater than 45°; (2) most stripped and
banded sedimentary structures have a bidirectional periodic evolution in vertical and some of stripped structures behave a compound of
multiple periods. According to the palaeogeography and the deep-water deposition environment of Qiongzhusi Formation, we suggest
that the deep-water contour currents are responsible for these deposits because of the large angle between the flow direction of
sedimentary currents and the dip azimuth of the ancient regional slope, and also an obvious period of the depositional currents. The
discovery of deep-water contourites in Qiongzhusi Formation has an important significance for understanding the distribution of shale
gas source rocks and reservoir of Qiongzhusi Formation in South China, as well as the survival conditions, death factors and
conservation conditions of the mollusks fossil in Chengjiang fauna.

Numerical Simulation Study on Influence of Loading Rate on Rock Uniaxial Compression Test

HUANGYehuan，LIU Chun，ZHANG Xiaoyu，QIN Yan，DENGShang

2019, 25(3):  423. 

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In numerical simulation of uniaxial compression, the loading rate is controlled by the variation range of boundary conditions
and the balance time after each change of boundary conditions. At the same loading rate, different combinations of the two factors will
have a great different on the loading effect. Therefore, exploring the influence mechanism of the above two factors on the numerical
simulation test of rock uniaxial compression can play a positive role in doing the efficient and high-precision numerical simulation test
under various loading rates. Using the MatDEM software, based on the loading area and standard equilibrium iteration which set by the
software automatically, changing the division number Nd and balance rate Rb to alter the loading rates of the uniaxial compression
numerical simulation tests. Through the analysis of the simulation results, the following conclusions can be obtained: (1) After one-step
loading, the more number of equilibrium iterations are, the more sufficient the propagation of the stress wave and kinetic energy
equals 0.8), the kinetic energy will decay sufficiently in each step, and the quasi-static simulation results can be obtained with the
lowest amount of calculation. (2) The smaller the stress increment of single-step loading is (the greater the Nd), the more accurate
numerical simulation results are. (3) When the loading rate is fixed and the amount of calculation is the same, loading schemes with low
single-step stress increment and lower balance iteration times (large Nd and small Rb) after single-step loading should be adopted to
ensure the accuracy of numerical simulation test. This paper provides a reference for quantitative study of rock loading rate and related
numerical simulation.

Gradation Analysis of Sand Particles Based on Digital Image Processing Technology

LYU Chao，TANG Chaosheng，LI Shengjie，XIE Yuehan，LIU Bo，XU Qiliang，WANGDongwei

2019, 25(3):  431. 

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Sand particle grading is one of the important parameters affecting the engineering properties of sand. The traditional grain
size analysis methods have different application range due to different test principles. In order to obtain sand particle gradation more
conveniently and accurately, a new method based on digital image processing technology to obtain sand particle size parameters and
grading characteristics in SEM photographs is proposed. The prepared sand samples are polished into thin slices and photographed
under a scanning electron microscope. Then the photos are stitched by Photoshop software, and the self-developed SMAS digital image
analysis system is used to quantitatively analyze the stitched photo to obtain the stuctural parameters of microscopic samples. The
obtained“equivalent diameter of soil particles”and“area of soil particles”are respectively equivalent to the actual soil particle size
and soil particle quality, which can be converted to the particle gradation curve of sand. The obtained sand particle gradation curve is
compared with the particle grading curve obtained by the traditional sieving method and laser particle size analysis method. The
validity and reliability of the proposed digital image processing method are verified. The differences between digital image processing
methods and traditional grain size analysis methods are analyzed, and their advantages as well as disadvantages are discussed.


Evaluation of Groundwater Environmental Disturbance by Mountain Highway Tunnel Construction

XIE Quanmin，DAN Shanlin，YANG Wendong

2019, 25(3):  437. 

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Due to the significant water converging corridor effect during the construction of a long tunnel, groundwater continuously
converge into the tunnel axis during construction, a series of hydro-geological disasters have been induced, which have caused
incalculable losses to construction workers and ecological environment around the tunnel area. In view of this, considering the
differences in individual cognition levels in group decision-making on the basis of system construction of mountain highway tunnel
construction on the groundwater environmental disturbance evaluation, an analytic model based on decision makers' preference
information is used in the field of environmental impact assessment of groundwater around the tunnel area, and the model is also
combined with fuzzy comprehensive evaluation method. The groundwater environment of Tibetan Mila Mountain Tunnel is evaluated
using this combined method. Results show that the disturbance degree of groundwater in the construction of Mila Mountain super-long
highway tunnel is in a general level. With the evaluation results, corresponding construction measures have been taken in the course of
the tunnel construction so that environment protection around the tunnel area can also be implemented. This provides a useful
reference for the tunnel EIA of groundwater in similar regions.

Advances of Genesis Analysis on Structural Geology in Oil and Gas Field Development

CHEN Huanqing，LIANG Shuxian，LI Wenqing

2019, 25(3):  444. 

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The genesis analysis of structural geology plays an important role in the oil and gas field development. Based on the research
advances in China and abroad, the advantages and disadvantages of the study in this field are compared in detail. There are eight
research directions in general. First, the structural geological genesis of fault system is determined through the analysis of structural
evolution history and stress field. Second, the genesis of geological structure was analyzed by means of detailed structural
interpretation. Third, explore and improve the research methods of structural geological genesis. Fourth, the geological genesis analysis
of reservoir is carried out based on comprehensive dynamic and static data. Fifth, structural geological genesis is studied by close
combination with sedimentary facies research and diagenesis research. Sixth, application of metallogenic analysis results should be
strengthened to provide a basis for the development of oil and gas fields. Seventh, microfracture characterization and modeling. Eighth,
microstructural geological genesis analysis. Methods of structural geological genesis analysis in oil and gas field development mainly
include: basic geological research, field description of outcrop observation, core observation and description, microscopic thin-section
observation, physical simulation, well logging, seismic interpretation, geochemical analysis and testing, geological modeling, dynamic
monitoring and dynamic analysis of production. The advantages and disadvantages of each method are analyzed based on case studies.
On this basis, it is concluded that there are eight main issues and eight future research directions in the study of the genesis of
structural geology in the oil and gas field development.

Development of Fractures and Its Effects on Gas Accumulation in the Upper Paleozoic Tight Sandstone Reservoirs of the Linxing Block

LIU Ling，TANG Dazhen，XU Hao

2019, 25(3):  457. 

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The Upper Paleozoic reservoirs in the Linxing block, Ordos Basin, were tight sandstones. Fractures characteristics and its
effects on gas accumulation were unclear. This limited the prediction of sweet spots in the region. Based on the data and analyses of
outcrop, core, thin section and well logging, the development characteristics of the fractures in the study area was analyzed, and their
effects on tight gas accumulation were discussed. Results show that the Upper Paleozoic reservoirs of the Linxing block mainly
developed high-angle fractures, followed by mid-low-angle and horizontal fractures. According to the relationship between fractures and
mineral grains, the intragranular fractures, the grain-edged fractures and grain-crossed fractures could be identified microscopically, of
which the grain-edged fractures were the most developed. Influenced by the plastic mudstones, vertical extension of the fracture was
poor, and thus the fractures usually disappeared in the mudstones after stretching one to two meters. Due to the northwest-southeast
ground stress in the Yanshanian period, the fracture strike was mostly northeast-southwest in trending, and the fracture density was two
to five every meter. The fractures could improve the reservoir’s porosity and gas filling efficiency. In the fracture areas, permeability
can be increased by one to two orders of magnitude and gas saturation is higher. In addition, the fractures were the effective pathway of
gas migration and affected the enrichment of tight sandstone gas. In the future exploration and development, the fracture-developed
area should be fully explored and further fracturing should be carried out to obtain higher production.period.

Geology and Geomorphology of Tarim Basin and Its Evolution in the Cenozoic

LI Jianghai，WUTongwen，LEI Yuting

2019, 25(3):  466. 

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The Tarim Basin is a unique giant geological and geomorphic unit in the hinterland of the Asian continent. It is a natural
laboratory for studying the new generation of the Earth system. Since the Cenozoic, it has experienced the geological evolution, such as
Paleogene Gulf, the Neogene lake-delta plain, the river-lake-desert, and the desert-river. The main factor affecting the change of
paleogeographical pattern is the long-range collisional orogeny, resulting in the closure of the basin and the onset of arid climate. Since
the Paleogene, the Gulf Basin has been low in the west and high in the east. The tectonic compression caused the uplift of the
surrounding mountains and the gradual closure of the basin, which is the most important driving factor for the basin evolution. During
the Neogene, it was high in the south and low in the north. With the uplift of the Qinghai-Tibet Plateau, the surrounding mountains
continued to rise, and the geological structure was constantly closed by the surrounding mountains, forming the Tarim Basin and
developing large lakes. Since the Quaternary, the basin has been high in the west and low in the east, and has experienced the fastest
evolution of the Earth system, forming China's largest inland water system and the largest desert. The coupling and interaction of
internal and external dynamics control the evolution of the Cenozoic Earth system in the Tarim Basin. The new tectonic structures in
the Tarim Basin are active. In the giant basin, rivers, lakes, deserts, Gobi, Yadan, dry salt lakes, etc. Different geological factors
interact in space and time, shaping the evolution of the Earth system in the giant basin. The geological history of the Tarim Basin
demonstrates the rapid evolution of the Quaternary Earth system in the extremely arid regions.

A New Leptomitid Sponge from the Early Cambrian Chengjiang Biota

YANG Jiyuan,MAHaidan, CHENAilin,HOUXianguang

2019, 25(3):  474. 

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This paper presents descriptions of Leptomitella spiralis sp. nov. from the early Cambrian Chengjiang biota, Yunnan
Province, China. The most typical character of L. spiralis sp. nov. is that the horizontal spicule bundles were spirally arranged around
the sponge body. Additionally, there are obvious distinctions in the external morphology and the types of spicules between L. spiralis sp.
nov. and other species within Leptomitella. New information obtained from L. spiralis sp. nov. increases the diversity of morphological
structure of Leptomitella, and also provides new data for exploring the early evolution and radiation of sponges in the Cambrian period.