Geochemistry and mineralogy of the Late Permian coals from the Songzao Coalfield, Chongqing, southwestern China

Mineralogy and geochemistry of the four main workable coal seams (No.6, No.7, No.8, and No.11) of Late Permian age from the Songzao Coalfield, Chongqing, Southwest China, were examined using in- ductively coupled plasma-mass spectrometry (ICP-MS), X-ray fluorescence spectrometry (XRF), cold-vapor absorption spectrometry (CV-AAS), ion-selective electrode (ISE), scanning electron mi- croscopy equipped with an energy-dispersive X-ray spectrometer (SEM-EDX), and X-ray diffraction analysis (XRD). The results showed that the main workable No.8 Coal that accounts for about 60% of the total coal reserves in the Songzao Coalfield was not enriched in hazardous trace elements. The No.11 Coal has high concentrations of alkaline elements, Be (9.14 μg/g), Sc (12.9 μg/g), Ti (9508 μg/g), Mn (397 μg/g), Co (23.7 μg/g), Cu (108 μg/g), Zn (123 μg/g), Ga (32 μg/g), Zr (1304 μg/g), Nb (169 μg/g), Hf (32.7 μg/g), Ta (11.4 μg/g), W (24.8 μg/g), Hg (0.28 μg/g), Pb (28.1 μg/g), Th (24.1 μg/g), and rare earth elements (509.62 μg/g). The concentration of Nb and Ta in the No. 11 Coal is higher than the industrial grade, and their potential utilization should be further studied. Besides pyrite, quartz, calcite, and clay minerals, trace minerals including chalcopyrite, marcasite, siderite, albite, mixed-layer clay minerals of illite and smectite, monazite, apatite, anatase, chlorite, and gypsum were found in the No.11 Coal. It should be noted that alabandite of hydrothermal origin and anatase occurring as cement were identi- fied in coal. In addition, the clayey microbands derived from alkaline volcanic ashes were identified in the coal. The dominant compositions of these clayey microbands were mixed-layer clay minerals of illite and smectite, which were interlayered with organic bands. The modes of occurrence of alkaline volcanic ash bands indicate that the volcanic activities were characterized by the multiple eruptions, short time interval and small scale for each eruption during peat accumulation. The alkaline volcanic ashes were the dominant factors for the enrichment of alkaline elements, Nb, Ta, Zr, Hf, and rare earth elements, and the sulfide minerals are the main carriers of Ga, Cu, and Hg in the No. 11 Coal.     

Lithology, kinematics and geochronology related to Late Mesozoic basin-mountain evolution in the Nanxiong-Zhuguang area, South China

The Nanling Mountain is an important Mesozoic orogenic belt in the south of China, its E-W-trending granites and adjacent sedimentary basins form a dis-tinctive basin-mountain landform. The Nanxiong basin and the Zhuguang granite, both located in the northern Nanling belt, make up a typical basin-mountain sys-tem. Since the 1970s, a systematical research on gran-ites and their deposit ores was carried out, from that the two main viewpoints were proposed[1—5], including (1) the polyphase gr…     

Faulting on the Anninghe fault zone, Southwest China in Late Quaternary and its movement model

The Anninghe fault is one of the significant earthquake-generating fault zones in the Southwest China. Local his-torical record shows that a M≥7 strong earthquake occurred in the year of 1536. On the basis of the detailed air-photographic interpretation and field investigation, we have acquired the following knowledge: 1 The average sinistral strike-slip rate since the Late Pleistocene is about 3~7 mm/a; 2 There is important reverse faulting along the fault zone besides the main left-lateral strike-slip motion, and the shortening rate across the Anninghe fault zone due to the reverse faulting is about 1.7~4.0 mm/a. If the Xianshuihe fault zone is simply partitioned into the Anninghe and Daliangshan faults, we can also get a slip rate of 3~7 mm/a along the Daliangshan fault zone, which is the same as that on the Anninghe fault zone. Moreover, on the basis of our field investigation and the latest knowledge concerning the active tectonics of Tibetan crust, we create a dynamic model for the Anninghe fault zone.     

Ar-Ar geochronology of Late Mesozoic volcanic rocks from the Yanji area, NE China and tectonic implications

Ar-Ar dating results of late Mesozoic-Cenozoic volcanic rocks from the Yanji area, NE China provide a new volcano-sedimentary stratigraphic framework. The previously defined “Triassic-Jurassic” volcanic rocks (including those from Sanxianling, Tuntianying, Tianqiaoling and Jingouling Fms.) were erupted during 118―106 Ma, corresponding to Early Cretaceous. The new eruption age span is slightly younger than the main stage (130―120 Ma) of the extensive magmatism in the eastern Central Asian Orogenic Belt and its adjacent regions. Subduction-related adakites occurring in the previously defined Quanshuicun Fm. were extruded at ca. 55 Ma. Based on these new Ar-Ar ages, the late Mesozoic to Palaeocene volcano-sedimentary sequences is rebuilt as: Tuopangou Fm., Sanxianling/Tuntianying Fm. (118―115 Ma), Malugou/Tianqiaoling Fm. (K1), Huoshanyan/Jingouling Fm. (108―106 Ma), Changcai Fm. (K2), Quanshuicun Fm. (~55 Ma) and Dalazi Fm. Our results suggest that subduction of the Pa- laeo-Pacific Ocean beneath the East Asian continental margin occurred during 106 to 55 Ma, consistent with the paleomagnetic observations and magmatic records which indicated that the Izanagi-Farallon ridge subduction beneath the southwestern Japan took place during 95―65 Ma.     

Paleogeographic evolution of the Lower Yangtze region and the break of the “platform-slope-basin” pattern during the Late Ordovician

Wide distribution of the black shales and diversification of the graptolite fauna in South China during the Late Ordovician resulted from its unique paleogeographic pattern, which was significantly affected by the paleogeographic evolution of the Lower Yangtze region. In the study, 120 Upper Ordovician sections from the Lower Yangtze region were collected, and a unified biostratigraphic framework has been applied to these sections to establish a reliable stratigraphic subdivision and correlation. Under the unified time framework, we delineate the distribution area of each lithostratigraphic unit, outline the boundary between the sea and land, and reconstruct the paleogeographic pattern for each graptolite zone. The result indicates that, with the uplift and expansion of the ‘Jiangnan Oldland' in the beginning of the late Katian, the oldland extended into the Yangtze Sea gradually from south to north, which finally separate the Jiangnan Slope and the Yangtze Platform. Consequently,the longstanding paleogeographic pattern of "platform-slope-basin" in South China was broken. The paleogeographic change led to sedimentary differentiation among the two sides of the ‘Jiangnan Oldland' during the Late Ordovician. This event also led to the closure of the eastern exit of the Upper Yangtze Sea, and formed a semi-closed, limited and stagnant environment for the development of the organic-rich black shales during the Late Ordovician. The major controlling factors of these paleogeographic changes in the Lower Yangtze region were not consistent from the Katian to the Hirnantian. In the late Katian, the sedimentary differentiation between the east and west sides mostly resulted from regional tectonic movement-the Kwangsian Orogeny.However, during the Hirnantian, the whole Yangtze region became shallower, which was mostly influenced by the concentration of the Gondwana ice sheet and the consequent global sea level drop.     

Geometry and Late Quaternary Kinematic Characteristics of the Huoshan Fault in Shanxi Province

The Huoshan fault is an important fault controlling the boundary of the Linfen basin at the middle transtensional segment of the Shanxi graben system.In this paper a discussion is made emphatically on the tectonic segmentation of the Huoshan fault,its internal geometric structures and characteristics of its activities since the late Quaternary on the basis of 1:10,000 scale geological mapping.Our investigations indicate that the Huoshan fault can be divided into 3 segments with different behaviors and structures.Among these 3,the shear segment with dextral movement is composed of a number of second-order shear faults in right-lateral stepover or left-lateral stepover arrangement.It has a maximum dextral displacement up to 9.83 km since the Pliocene,a dextral slip rate of 2.0 mm/a; a maximum vertical differential displacement of 3.44 km,and a differential oscillatory movement rate of 0.69 mm/a.The lower limit of dextral Holocene slip rate is about 5 mm/a.     

Recent and Late Holocene vertical crustal movements in the Southeast Baltic—The transition zone between the Fennoscandian shield and the Russian plate

The paper analyzed recent vertical crustal movements and compared them with Late Holocene ones (over several thousands of years) with the case study of the transition zone between the Fennoscandia shield and the Russian plate. The study of recent and young movements is based on long-term sea level and repeated geodetic measurements and on geologic geomorphic data, respectively. The data set makes it possible to establish that a weak uplift of the territory gives way with regularity to a weak subsidence after going across the zone of zero movements that agrees with the modern geodynamic constructions and can serve as the basis of long-term prognostic estimations. The results are compared with the newest GPS measurements and with the theoretical model of viscoelastic deformations in the periphery of the past glaciation area during its postglacial isostatic adjustment     

On the faults of western Hexi Corridor and its nearby regions, northwestern China:Thrust faults and strike-slip faults of Late Cenozoic

Introduction Hexi Corridor, a corridor extended over 1 000 km and with a strike of WNW-ESE, is locatedbetween Alxa uplift and northern Qilianshan Caledonian folding belt of northern Qinghai-Xizang(Tibet) Plateau (Figure 1). In the paper, we will discuss the regions between Altun fault and Yu-mushan of the western Hexi Corridor, where the climate is arid, which results in sparse vegetation,but abundant oil and gas resource, and being one of the most important petroleum industry base…     

Monazite age spectra in the Late Cenozoic strata of the Changjiang delta and its implication on the Changjiang run-through time

Uplift of the Tibetan Plateau, inversion of eastern and western geomorphology, eastward flowing of large rivers, and run-through of the Changjiang River exert great influence on sedimentation and environ-mental variations in the East China Sea. Provenance discrimination of Tibetan-Plateau-originated sediments in the river-mouth areas and marginal seas is key to figure out these issues.In the past, most studies of the run-through time of the Changjiang and the Yellow rivers focused on geomo…     

Deformation Patterns and Shortening Rates in the East Part of the Kalpin Thrust System in the Southwest Tianshan Mountains During the Late Quaternary

Deformation patterns, shortening amounts and rates in the late Quaternary across the Kalpin thrust system have received little attention in the past. This paper attempts to discuss them, mainly in the eastern part of the thrust system by doing field investigation along the faults and folds, measuring geomorphic deformation, excavating trenches in several important sites where young alluvial fans were obviously displaced and dating young deposits of alluvial terraces. There are two types of deformation in the surface and near surface for the Kalpin thrust system in the late Quaternary. They are movement of thrust faults on lower angles and bending of young folds. Both kinds of deformation are shown by shortening and uplifting of young geomorphic surfaces. The surface ages of 3 stages are calculated by dating 20 examples using the TL method in the study area and comparing the results of our predecessors on the deposition and incision times of alluvial terraces in the Tianshan mountain which are 100ka B.P., 33～18ka B.P. and 6.6～8.2ka B.P. respectively for the large-scale deformed alluvial surfaces: T_3, T_2 and T_1 in the Kalpin region. Then, 19 sets of shortening amounts and rates are obtained in 13 sites along 4 rows of anticlines in front of the Kalpin thrust system and Piqiang fold. The shortening amounts and rates show that there are two sections where deformation is stronger than others. The two sections consist of two arcs that are towards the south. The shortening rates near the top of arcs are 1.32mm/a in the west and 1.39mm/a in the east across the thrust system, respectively. In addition, deformation is stronger in the front rows than the rear ones for bifurcate folds.     

Late Pleistocene and Holocene activity of the Atacazo–Ninahuilca Volcanic Complex (Ecuador)

The Atacazo–Ninahuilca Volcanic Complex (ANVC) is located in the Western Cordillera of Ecuador, 10 km southwest of Quito. At least six periods of Pleistocene to Holocene activity (N1 to N6) have been preserved in the geologic record as tephra fallouts and pyroclastic flow deposits. New field data, including petrographic and whole-rock geochemical analyses of over forty soil and tephra sections, 100 pumice and lithic samples, and 10 new ¹⁴C ages allow us to constrain: (1) the tephra fall isopachs and detailed characteristics of the last two events (N5–N6) including volume estimates of the tephra and pyroclastic flow deposits and the corresponding volcanic explosivity index (VEI); (2) the petrographical and geochemical correlations between domes, tephras, and pyroclastic flow deposits; and, (3) the timing of the last 4 eruptive events and a period of quiescence that endured a few thousand years (1000–4000).     

Late Quaternary sinistral slip rate along the Altyn Tagh fault and its structural transformation model

The Altyn Tagh Fault (ATF) is a major boundaryfault on the northern margin of the Qinghai-TibetanPlateau and is also the longest sinistral strike-slip faultat a lithospheric scale in the Eurasian Plate. Its exis-tence has directly affected regional features of neotec-tonics, topography, geomorphology, Quaternary geol-ogy, recent crustal deformation, seismicity, climatechange and ecological environment for fauna and florain China[1—6]. The sinistral slip on the ATF and activethrusting-fo…     

Active Feature of the Ganzi-Yushu Fault Zone in the Late Quaternary

Based on regional geological mapping results and interpretation of satellites images and areophotos in combination with detailed field study,this paper gives the spatial distribution of recent surface activity of the Ganzi-Yushu fault zone(GYF).According to faulted landform as well as deformation and displacement of young deposit layers,the slip rates of GYF since the late Quaternary are briefly studied,combined with the results of geological chronology(14C and Thermoluminescene dating).The result shows that the average slip rates of GYF is differentiate along different segments:Ganzi segment:horizontal rate is 3.4±0.3 mm/a,vertical rate is 2.2±0.1 mm/a;Manigange segment:horizontal rate is 7.0±0.7 mm/a;Denke segment:horizontal rate is 7.2±1.2 mm/a;Dangjiang segment:horizontal rate is 7.3±0.6 mm/a.     

Characteristics of the Activity of the Lintong-Chang＇an Fault in the Late Pleistocene

Analysis of fault outcrops and trench sections indicates fault displacements of 0.2m - 6.0 m on the bottom paleosol layer of the Epipleistocene with the maximum rate of 0.047 mm/a and an average displacement of 1.1 meters. The activity appears as fissures on the fault surface in the late Epipleistocene and there is no obvious displacement. The fault activity is weak and the most active segment is the Bailuyuan segment.     

Late Cenozoic Stratigraphic Sequence and Its Implication to Tectonic Evolution, Hejiakouzi Area, Ningxia Hui Autonomous Region

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Temporal and spatial variation and stability of the oasis in the Sangong River Watershed, Xinjiang, China

The unique ecological landscapes are composed of the mountain systems with the obviousvertical differentiation, vast natural desert systems, and oasis systems on which the human beings rely for the existence in the arid areas in West China. Oases are the …     

Relationships between bacterial-algal proliferating and mass extinction in the Late Devonian Frasnian-Famennian transition: Enlightening from carbon isotopes and molecular fossils

The five major mass extinctions which occurred in the transition of the Ordovician-Silurian (440 Ma), Late Devonian Frasnian-Famennian (F-F) (370 Ma), Permian-Triassic (250 Ma), Triassic-Jurassic (205 Ma) and Cretaceous-Paleogene (65 Ma) are significant phenomena in the Phanerozoic global environment and organic evolution. Their corresponding extinction rates of marine invertebrate at the level of genus and family are 60% (genus) and 26% (family), 57% and 22%, 82% and 51%, 53% and 22%, …     

Division of Buried Late Quaternary Strata of the Fuzhou Basin

INTRODUCTIONThe Fuzhou basinis located on the west bank of the Taiwan Straits in the southeastern coast ofChina. Accompanied with the regional crust movement and sea level fluctuating, marine facies ,continental facies and marine-continental alternant facies sediments are developedinthe Fuzhou basintogether withthe contiguous basins ,suchas Fuqing,Putian,Quanzhouand Zhangzhouof southeasternFujian. These sediments have complicated sedimentary structure and the underlying bedrock iscompo…     

Activity Feature of Kazkeaerte Fault Zone in the Late Quaternary

ＩＮＴＲＯＤＵＣＴＩＯＮＫａｚｋｅａｅｒｔｅｆａｕｌｔｚｏｎｅａｂｏｕｔ 1 0 0ｋｉｌｏｍｅｔｅｒｓｌｏｎｇ (Ｆｉｇ .1 ) ,ｉｓｔｈｅｅａｓｔｅｒｎｌｉｍｂｏｆｔｈｅｌａｔｅｓｔｄｅｆｏｒ ｍａｔｉｏｎｂｅｌｔｏｆｔｈｅｎｏｒｔｈｅｒｎｍａｒｇｉｎｏｆＰａｍｉｒｓ (ＣｈｅｎＪｉｅ ,ｅｔａｌ,1 997) .Ｍａｎｙｍｏｄｅｒａｔｅｌｙｓｔｒｏｎｇｅａｒｔｈ ｑｕａｋｅｓｏｃｃｕｒｒｅｄａｌｏｎｇｔｈｉｓｚｏｎｅ (ＦｅｎｇＸｉａｎｙｕｅ ,ｅｔａｌ,1 987) .ＴｈｅｌａｔｅＱｕａｔｅｒｎａｒｙｄｅｆｏｒｍａｔｉｏｎ…