Middle-upper Part Research Articles

The influence of reinforcement strengthening on seismic response and index correlation for high arch dams by endurance time analysis method

This study aims to explore the correlation between the seismic response indices of high arch dam with and without cantilever reinforcement strengthening. The nonlinear dynamic responses of the 289-m-high Baihetan dam located in southwestern China, to three-component endurance time acceleration histories are investigated. The dynamic responses, including damage distribution, displacement, and joint opening, are statistically analyzed. Furthermore, the proposed seismic response indices, including the global and local damage volume ratios, the average joint opening, and the displacement of the crown cantilever are studied. By comparing the seismic response indices with and without reinforcement, the effects of cantilever reinforcement on the changing trend and range of the seismic response indices are discussed. Subsequently, the correlation curves of the seismic response indices are demonstrated, and the correlation calculated with reinforcement between the seismic response indices is identified. To provide a better correlation analysis, the correlation of each seismic response index is classified. Numerical results show that the changing trend of correlation of the damage indices v. the upstream displacement is different from that of the damage indices v. the downstream displacement. When the peak ground acceleration is approximately 0.5 g, cantilever reinforcement has a significant effect on limiting damage development in the middle-upper part of the downstream face. However, cantilever reinforcement has a limited effect on the correlation between each seismic response index under different peak ground accelerations.

Analysis of stability of the Baihetan arch dam based on the comprehensive method

In this paper, the stabilities of the Baihetan arch dam were analyzed by combining a geomechanical model test and the 3D nonlinear finite element method (FEM) based on the comprehensive method. The deformation characteristics and failure patterns of the dam, abutments, and foundations under different overload conditions were modeled and analyzed by the geomechanical model test. Then, the 3D nonlinear finite element calculation was conducted for complement and verification, by which the deformation characteristics and plastic failure zones of the dam and foundation under different overload stages were simulated. Based on the deformation behaviors, failure pattern, and the development of plastic zones of weak structure planes and rock mass in the dam’s abutments and foundation, the impacts of weak structure planes on the safety coefficient of dam abutment and foundation were analyzed. The geomechanical test results and FEM results demonstrated consistency in this study and provided an important basis for engineering safety assessment. The results indicated that the Baihetan arch dam meets the principal stability requirements; however, considering the large deformation and serious cracks in the middle-upper part of the left dam abutment, reinforcement treatment is proposed to improve the abutment stability of the Baihetan arch dam.

Optimization of the construction sequence of the expanding excavation around Tunnel

With the background of the construction of the Loushan Tunnel, Flac3D software was used to simulate three different expanding excavation sequence schemes. The simulation results were compared and selected, and it determined that Scheme3 is the best scheme. In the construction site, tunnel vault settlement and hance convergence were measured and compared with the simulation results. Conclusions are as follows: ①The final vertical displacement of Scheme.1 was greater than that of Scheme.2 and Scheme.3. In scheme 2, the horizontal displacement of the middle-upper part of the tunnel increased sharply after the excavation of the upper-right part. The maximum bending moment of the supporting structure of Scheme.3 was smaller than that of the other two schemes. In addition, the maximum bending moment in the whole process of expanding excavation transited smoothly, and it fluctuated the most in Scheme.2; ②When the upper-left part is expanded, the vertical displacement and bending moment of the supporting structure of the three schemes all increase greatly. In the actual construction, the most unfavorable factor is that the settlement detection value of the vault increases rapidly after the expanding excavation of the upper-left part; ③The construction sequence adopts Scheme.3, the settlement value & convergence value becomes more and more stable about 7 after excavation, the accumulated settlement value is 17.146mm, and the accumulated convergence value is 14.512mm. The field data is close to the simulated data, no accidents occur in the construction process, and no abnormal phenomena are found in the monitoring and measurement process.

A Miocene Phreatoplinian eruption in the North-Eastern Pannonian Basin, Hungary: The Jató Member

A Middle Miocene, ~8 m thick pyroclastic succession, reported from the Bükk Foreland Volcanic Area (BFVA) in Northern Hungary (Central Europe) specified here as the Jató Member, was produced by silicic phreatomagmatism (Phreatoplinian sensu lato). Two well-preserved outcrops ~8 km apart and inferred to be within ~10–50 km from source represent the discontinuously exposed, layered, paleosol-bounded, phreatomagmatic Jató Member. They show an identical phenocrystal assemblage of feldspar, biotite and amphibole without weathered zones or signs of erosion, that suggest deposition in one eruption phase lasting hours to months. The succession contains three subunits: 1) subunit A, 1.8 m thick, a series of well-sorted fine to coarse ash or lapilli tuff layers with constant thickness; 2) subunit B, 2.1 m thick, a series of normal-graded layers with an upper fine-grained zone containing abundant ash aggregates with a coarser-grained core and distinctively finer-grained outer rim; 3) subunit C, 4.5 m thick, a massive, poorly to well-sorted coarse ash with gas escape structures and ash aggregates at its base. The upward change of these lithofacies implies an initially sustained dry fallout-dominated deposition of ash and pumice lapilli resulting in subunit A. Subsequently, multiple wet and dilute Pyroclastic Density Currents (PDCs) dispersed subunits B and C. The general abundance of PDC-related ash aggregates in the middle-upper part of the succession (particularly in subunit B), and the transformation of a fall-dominated to a collapsing depositional regime producing wet dilute PDCs, imply the increasing influence of water during the eruption (Phreatoplinian sensu lato). The presence of water is related to an epicontinental sea during Middle to Late Miocene in the Carpatho-Pannonian region. The transition from an initial dry magmatic phase generated fallout activity followed by the emplacement of wet PDCs' rich in ash aggregates, when external water infiltrated from a surrounding lake or sea water entered the vent.

Characteristics and Formation Tendency of Freckle Segregation in Electroslag Remelted Bearing Steel

Undesirable macro segregation defects, freckles, restrict the commercial production of large-sized electroslag remelting (ESR) bearing steel ingots through degradation of the mechanical properties and service lifetime. In order to clarify the freckle characteristics and formation tendency as well as the formation mechanism, freckles from an industrial large-sized GCr15SiMn ESR ingot were investigated through structural and compositional analysis, along with simulation calculation. The results show that freckles consist of (Si, Mn, Cr)-enriched equiaxed grains and occur in about the 1/2 radius region at the middle-upper part of the ESR ingot, where the secondary dendritic arm spacing (SDAS) and solidification front angle are large but cooling rate is small. The absolute value of relative Rayleigh number, Ra, also reaches its maximum in the 1/2 radius region, with a liquid fraction of 0.3–0.5, corresponding to the region where freckles form. Based on the experimental and simulation results, to evaluate the freckle formation in industrial-scale GCr15SiMn ESR ingots, the threshold value of relative Ra, a freckle criterion considering the compositional and thermal effects, was determined to be about −0.023.

Benthic Foraminifera Across the Cretaceous/Paleogene Boundary in the Eastern Tethys (Northern Alborz, Galanderud Section): Extinction Pattern and Paleoenvironmental Reconstruction

AbstractExtinction patterns, paleobathymetric inferences, and paleoenvironmental changes based on benthic foraminifera were investigated across the Cretaceous/Paleogene (K/Pg) boundary at the Galanderud section (Northern Alborz, Iran), which contains one of the most continuous and expanded K/Pg transitions in the eastern Tethys. On the basis of benthic foraminiferal taxa abundance and distribution, an outer neritic to uppermost bathyal paleo-depositional setting is inferred. In addition, benthic foraminiferal assemblages and planktic/benthic ratios do not indicate any major change in relative sea level during latest Maastrichtian-early Danian time.Changes in benthic foraminiferal assemblages, morphotypes, diversity, heterogeneity, and benthic foraminiferal oxygen index, coupled with statistical analyses, define three intervals. In the first interval (uppermost Maastrichtian Plummerita hantkeninoides Zone), benthic foraminiferal assemblages are moderately to well preserved and highly diverse, with a combination of epibenthic and endobenthic taxa indicating stable, mesotrophic to weakly eutrophic, normal marine conditions. A major change in benthic foraminiferal assemblages at the K/Pg boundary defines a second interval (basal Danian Guembelitria cretacea and lower part of Parvularugoglobigerina eugubina Zones) that is marked by a decrease in the endobenthic morphogroups as well as a decrease in diversity, heterogeneity, genus and species richness. This second interval denotes highly oligotrophic conditions and a collapse in productivity and food availability due to the extinction of some primary producers, with the exception of the three chalk beds representing short-lived blooms of calcareous dinoflagellates. Benthic foraminifera do not show significant extinction at the end of the Cretaceous at this section with only about an 8% loss of species. Additionally, the abundance of some opportunistic species, including Cibicidoides pseudoacutus and Tappanina selmensis, may reflect instability in the benthic foraminiferal assemblages. The third interval (middle-upper part of the Pv. eugubina Zone) is characterized by the dominance of epibenthic morphogroups (up to 70% of the assemblages) with a partial recovery of endobenthic groups. The characteristics of the benthic foraminiferal assemblages indicate that the flux of food to the benthos had not fully recovered during the early Danian.

Provenance analysis of the late Mesoproterozoic to Neoproterozoic Xuhuai Basin in the southeast North China Craton: Implications for paleogeographic reconstruction

The late Mesoproterozoic to Neoproterozoic sedimentary rocks in the southeast North China Craton (NCC) are significant in paleogeographic reconstruction. An integrated approach of field investigation, detrital zircon U-Pb dating, and Lu-Hf isotope analysis reveals essential information on the tectonic-sedimentary evolution of the Xuhuai Basin. New age constraints show that the Xuhuai Basin comprises a lower (Huaihe Group, 1.1–0.9 Ga) and an upper (Langan Group, <0.82 Ga) successions, with an unconformity between them. The depositional age of the middle to upper part of the Huaihe Group (the Niyuan-Wangshan formations) is limited to 0.97–0.89 Ga. A comparison of regional basin formations suggests that the Xuhuai, Jiaolai, Dalian, and Pyongnam basins belong to the same rift system (the Xuhuai rift system). There was a distinct provenance change from ~2.7–2.5 Ga, ~2.1 Ga and ~1.9 Ga rocks (zircon ages) in the lower part, to 1.8–1.0 Ga in the middle-upper part of the Huaihe Group, and back to ~2.7–2.5 Ga, ~2.1 Ga and ~1.9 Ga rocks in the Langan Group. The ~2.7–2.5 Ga, ~2.1 Ga, ~1.9Ga, and ~1.8–1.4 Ga provenances could be from the NCC, while the 1.2–1.0 Ga provenances were possibly from the Grenvillian orogens which could be far or close neighbors of the NCC before 0.9 Ga. While both the 1.4–1.3 Ga and 1.2–1.0 Ga provenances possibly support a North China-São Francisco-Congo connection hypothesis, in which the Early Neoproterozoic basins such as the Xuhuai rift basins along the southeastern margin of the NCC, the coeval basins along the eastern and western margins of the São Francisco Craton and the west Congo Craton comprise a correlated rift system during 1.1–0.9 Ga.

Comparative Analysis of Dynamic Responses of Different Rock Tunnel Slopes

Large-scale shaking table tests and numerical simulations are performed to analyze the commonality and difference of the seismic responses between two rock tunnel slopes. One is a slope with a single tunnel, the other is a slope with small spacing tunnel, and both have the same slope size and tunnel size. Two recorded ground motions with different amplitudes are applied in three directions. The results show that the acceleration amplification effect of two slopes both presents obvious nonlinear characteristics along the height of slope. The acceleration amplification effects of two slopes mainly appear at the middle-upper part of slope under horizontal seismic excitation, whereas those mainly appear near the slope crest under vertical seismic excitation. Whether in horizontal or vertical excitation direction, the acceleration amplification effect of the slope containing small spacing tunnel is greater than that of the slope containing single tunnel. There is a significant difference in seismic response between small spacing tunnel and single tunnel. The maximum horizontal displacements of two slopes are on the slope crest. With the increase of the input earthquake amplitude, the peak displacement of the slope containing small spacing tunnel is gradually approaching and exceeding that of the slope containing single tunnel. The arch springing, the tunnel vault, the middle rock pillar and the slope foot of the slope containing spacing tunnel require special enhancements for seismic design, whereas the special reinforcement area of the slope containing single tunnel is the arch springing and the tunnel vault.

Development of a groundwater flow and reactive solute transport model in the Yongding River alluvial fan, China

The Yongding River in the western suburbs of Beijing has been recharged with reclaimed water since 2010 for the purpose of ecological restoration. Where the reclaimed water is not well treated, it poses a danger to the aquifer underneath the river. To provide a reliable tool which could be used in future research to quantify the influence of reclaimed water in the Yongding River on the local groundwater environment, a transient groundwater flow and reactive solute transport model was developed using FEFLOW™ in the middle-upper part of the Yongding River Alluvium Fan. The numerical model was calibrated against the observed groundwater levels and the concentrations of typical solutes from June 2009 to May 2010 and validated from June 2010 to December 2010. The average RMSE and R2 of groundwater level at four observation wells are 0.48 m and 0.61, respectively. The reasonable agreement between observed and simulated results demonstrates that the developed model is reliable and capable of predicting the behavior of groundwater flow and typical contaminant transport with reactions. Water budget analysis indicates that the water storage in this aquifer had decreased by 43.76×106m3 from June 2009 to December 2010. The concentration distributions of typical solutes suggest that the middle and southern parts of the unconfined aquifer have been polluted by previous discharge of industrial and domestic sewage. The results underscore the necessity of predicting the groundwater response to reclaimed water being discharged into the Yongding River. The study established a coupled groundwater flow and reactive solute transport model in the middle-upper part of the Yongding River Alluvium Fan, one of the drinking water supply sites in Beijing city. The model would be used for risk assessment when reclaimed water was recharged into Yongding River.

Source Analysis of Silicon and Uranium in uranium-rich shale in the Xiuwu Basin, Southern China

Abstract Uranium deposits are crucial resources for the development of the nuclear energy. Among known sources of uranium, the uranium-rich shales have recently obtained significance. In this paper, the Lower Cambrian Wangyinpu Formation shale in the Xiuwu Basin, southern China, has been studied using a combination of techniques including element analysis (Al, Fe, and Mn), δ30Si silicon isotopic analysis, δ18O oxygen isotopic analysis, study of core samples. It has been observed that significant hydrothermal activity occurred in the Xiuwu Basin during the Early Cambrian period. The results show that 20%–40% of the silicon in most of the sections of the Lower Cambrian Wangyinpu Formation were inherited from the hydrothermal fluids, with temperatures ranging between 75∘C and 102∘C. It is concluded that more than 90% of the uranium in most of the sections of the Lower Cambrian Wangyinpu shale was derived from submarine hydrothermal fluids, while less than 10% from the terrigenous detritus. The enrichment of uranium in the basin was observed in the Middle-Upper part of the Wangyinpu Formation and the geological resources estimated to a tune of ~4.9×103 t. In this paper, we proposed a model for silicon and uranium enrichment in the Lower Cambrian shale controlled by hydrothermal activity in the Xiuwu Basin. This model also provides a scientific rationale for uranium further exploration and exploitation of the uranium resource.

Sedimentary characteristics, formation mechanisms and geological significance of the Shiniulan Formation reefs (lower Silurian) in the Upper Yangtze Platform

The lower Silurian Shiniulan Formation of the Upper Yangtze Platform contains small-scale coral–stromatoporoid reefs, generally from less than 10 km long and from 10 to 30 m in thickness, especially in the middle–upper parts. The reef-building organisms were dominantly tabulate and rugose corals, with fewer stromatoporoids. Reef-inserted organisms include bryozoans, brachiopods, cephalopods, algae, crinoids and bivalves. The Shiniulan Formation is characterised by biohermal limestone, bioclastic limestone, sandstone and mudstone, and is divided into four members according to lithological characteristics. The reefs generally occur in the middle–upper layer, which corresponds to four growth stages: stabilisation, colonisation, diversification and domination. In the reefs, the argillaceous and sandy contents decrease, and the carbonates increase from the base to the top. The growth characteristics, evolution, scale and size of the reefs in the Shiniulan Formation were influenced by three factors: agitation of terrigenous debris, fluctuation of sea level and seawater temperature. The Upper Yangtze region was mainly a shallow marine environment with a warm or torrid tropical and subtropical climate and high salinity in the late Aeronian. However, the Shiniulan Formation has significant differences in growth, evolution and extension scale compared with corresponding reefs in Laurentia and the Siberia and Kazakhstan blocks. Analysis of the geological factors of the Shiniulan Formation and the Menier Formation of Anticosti Island, which has revealed that the two sections have similar reef types, lithology and biology, aims to explain the under-development of large-scale reefs in the Upper Yangtze Platform during the middle–upper Silurian.

Petroleum source and accumulation of WZ12 oils in the Weixi'nan sag, south China sea, China

Abstract Source rocks are found in the Eocene Liushagang Formation (El1: bottom, El2 and El3:top members), in the Weixi'nan sag, Beibuwan Basin. The source rocks are mainly mudrocks, except El2, which consists of organic-rich shales at the bottom and mudrocks in the middle-upper part. Total organic carbon (TOC) and Rock-Eval analyses of 146 samples indicate that El2 rocks have the best hydrocarbon generating potential, especially for organic-rich shales that contain up to 10% TOC with HI > 800 mg/g. The vitrinite reflectance analysis suggests that El source rocks are marginally mature to mature. Geochemical analyses were conducted on 18 El rock extracts and 18 oil samples from the WZ12 field. El2 and El3 source rock have similar organic facies and are distinct from El1. El2 and El3 have higher C27 βα (20R + 20S) diasteranes/C27 αββ (20R + 20S) steranes (C27DiaS/C27S), Gammacerane/Hopane (G/H) and (C28 + C29) tricyclic terpane/((C28 + C29) tricyclic terpane + Ts) (ETR), and low C23 tricyclic terpane/hopane (C23/H) and C24 tetracyclic terpanes/C26 tricyclic terpane (C24/C26). These biomarker distributions indicate that El2 and El3 rocks were deposited under more alkaline-saline environment and had less import of terrestrial organic matter relative to El1. El2 can be distinguished from El3 as having higher 4-methylsteranes/C29 ααα steranes (4MSI) and G/H. WZ12 oils all exhibit similar compositions and display biomarker characteristics that correlate with the El2 and El3 rock extracts. 1D thermal and burial history model shows that El2 and El3 began to generate a great deal of hydrocarbon at ∼11.5 Ma and 23 Ma, respectively. At this stage, traps formed and faults actively extended downwards into the El2 and likely into El3. Oils expelled from El2 and El3 migrated upward into shallow intervals along faults then laterally along the structural slopes and accumulated in areas with good fault sealing primarily in the Miocene age Nx and Nj strata. Meanwhile, under the effect of overpressure in the middle of organic-rich shales, oils from El2 may have migrated downward into reservoirs in the upper part of El3. Lithologic traps in El1 reservoir may be charged with relatively immature oil derived from El1.

Early Permian transgressive–regressive cycles: Sequence stratigraphic reappraisal of the coal-bearing Barakar Formation, Raniganj Basin, India

The present research is an attempt to assess the Barakar Formation of the Raniganj Gondwana Basin, India, in the frame of fluvio-marine (estuarine) depositional systems using sequence stratigraphic elements. Analysis of predominant facies associations signify deposition in three sub-environments: (i) a river-dominated bay-head delta zone in the inner estuary, with transition from braided fluvial channels (FA-B1) to tide-affected meandering fluvial channels and flood plains (FA-B2) in the basal part of the succession; (ii) a mixed energy central basin zone, which consists of transitional fluvio-tidal channels (FA-B2), tidal flats, associated with tidal channels and bars (FA-B3) in the middle-upper part of the succession; and (iii) a wave-dominated outer estuary (coastal) zone (FA-B4 with FA-B3) in the upper part of the succession. Stacked progradational (P1, P2)–retrogradational (R1, R2) successions attest to one major base level fluctuation, leading to distinct transgressive–regressive (T–R) cycles with development of initial falling stage systems tract (FSST), followed by lowstand systems tract (LST) and successive transgressive systems tracts (TST-1 and TST-2). Shift in the depositional regime from regressive to transgressive estuarine system in the early Permian Barakar Formation is attributed to change in accommodation space caused by mutual interactions of (i) base level fluctuations in response to climatic amelioration and (ii) basinal tectonisms (exhumation/sagging) related to post-glacial isostatic adjustments in the riftogenic Gondwana basins.

Forest stability during the early and late Holocene in the igapó floodplains of the Rio Negro, northwestern Brazil

AbstractLocated at the northwestern part of the Amazon basin, Rio Negro is the largest black-water river in the world and is one of the poorest studied regions of the Amazon lowlands. In the middle-upper part of the Rio Negro were retrieved sediment cores form Lake Acarabixi, which were analyzed using pollen, spores, charcoal, and geochemistry. The aim of this study was to detect the influences from humans and river dynamics on the vegetation history in the region. Two main periods of vegetation and river dynamics were detected. From 10,840 to 8240 cal yr BP, the river had a direct influence into the lake. The lake had a regional input of charcoal particles, which reflected the effect of the dry Holocene period in the basin. Furthermore, highland taxa such asHedyosmumandMyrsinewere found at that time along with igapó forest species that are characteristic to tolerate extended flooding likeEschweilera,Macrolobium, Myrtaceae,Swartzia, andAstrocaryum. During the late Holocene (1600 to 650 cal yr BP), more lacustrine phases were observed. There were no drastic changes in vegetation but the presence of pioneer species likeVismiaandCecropia, along with the signal of fires, which pointed to human disturbances.

Petrology and geochemical characteristics of dolomite in the Middle Permian Maoukou Formation, central Sichuan

Dolomites of the Maokou Formation in the central Sichuan were mainly developed in the middle-upper part of Member 2 and the lower part of Member 3 of Maokou Formation, it could be divided into fine-to medium-grained calcareous dolomite, fine-to medium-grained dolomite and breccia dolomite according to petrology characteristic, and the latter two were dominant. Through contrast of geochemical characteristic between micritic limestone and different types of dolomite, the dolomite was characterized by low Fe content, high Mn content and low Sr content relative to the micritc limestone. The micritic limestone and different types of dolomite had similar rare earth element (REE) distribution patterns which were characterized by depletion of light REE, weak positive anomaly of La and negative anomaly of Ce, and the dolomite also had weak positive anomaly of Eu. Compared with the micritic limestone, the fine-to medium-grained dolomite and breccia dolomite had low values of δ18O and obvious high ratios of 87Sr/86Sr. REE distribution patterns of different types of dolomite indicated that some geochemical characteristics of primitive limestone were preserved during the dolomitization process in the Maokou Formation, while weak Eu positive anomaly of dolomite and isotopic difference in dolomite and limestone might be caused by high-temperature thermal fluids during the dolomitization process. The dolomitization of the Maokou Formation was controlled by some factors: (1) strata residual seawater and hydrothermal fluids derived from magmatism were major sources of Mg during the dolomitization process; (2) heating effect of Emeishan large igneous province provided abnormal high paleo-geotemperature for dolomitization; (3) fault systems offered rapid migration channels for abnormal geothermal convection and dolomitization fluid; (4) limestone of grain-shoal facies with good porosity and permeability was more prone to dolomitization than micritic limestone. Abnormal geotemperature and abundant Mg supply derived from Emeishan Large Igneous Province were key factors for dolomitization in the Maokou Formation, and different types of dolomites were formed in different periods of the dolomitization process.

Tremadocian (Early Ordovician) chitinozoan biostratigraphy of South China: An update

The lowest Ordovician (Tremadocian) chitinozoan biostratigraphy of the South China Palaeoplate has been reviewed and updated, based on new investigation from the Upper Yangtze area. The systematic paleontology of Lagenochitina pestovoensis Obut 1973 and Lagenochitina destombesi Elaouad-Debbaj 1988, has been revised. Previous identifications of L. destombesi from South China are considered questionable, and the L. destombesi Biozone, recognized from Baltica, northern Gondwana and peri-Gondwana, is therefore no longer used for the middle-upper part of the Tremadocian in South China. Two chitinozoan biozones are recognized, including the Lagenochitina pestovoensis Biozone (lower) and the Euconochitina symmetrica Biozone (upper) for the middle and upper part of the South Chinese Tremadocian. International correlation of the E. symmetrica Biozone indicates that the base of this biozone in South China is lower than the records in North America and northern Gondwana, and that the biozone is confined within the upper Tremadocian in South China.

Geochronological constraints on stratigraphic correlation and oceanic oxygenation in Ediacaran-Cambrian transition in South China

The continuous late Ediacaran - early Cambrian deep-water successions of South China archive the complete evolution of seawater chemical conditions in the deep ocean during this critical time interval. However, the geochemical data from these poorly fossiliferous and condensed successions lack high-resolution stratigraphic constraints, hampering their interpretation for the spatio-temporal evolution of the sweater chemistry in this time interval. In this study, we report a new SIMS and CA-ID-TIMS zircon U-Pb age 545.76±0.66Ma (total uncertainty) for an ash bed at the lower Liuchapo Formation in the deep-water Longbizui section in western Hunan Province. The new age suggests that the lower and the middle-upper parts of the Liuchapo Formation in the deep water facies can be correlated with the lower Dengying Formation and the upper Dengying - lower Zhujiaqing formations in the shallow water facies, respectively. This correlation implies that the correlative horizon of the Ediacaran-Cambrian boundary in the deep water facies in South China is likely located near the base of a widespread negative δ13Corg excursion at the upper Liuchapo Formation. Based on our new geochronological framework, the compilations of Fe-speciation, Mo, and U data indicate that the deep ocean was characterized by widespread anoxic, ferruginous water, with intermittent euxinic water impinged on the middle-lower slope in Ediacaran-Cambrian transition, and significant oxygenation events occurred in 533–520Ma. The compilations do not support any significant oceanic oxygenation events in 551–535Ma.

Campanian–Maastrichtian foraminiferal stratigraphy and palaeoenvironment of the Lower Tar Member in the Wadi Tar section, Western Sirte Basin (Libya)

Upper Campanian–Maastrichtian sections on the western flank of the Hun Graben in the Western Sirte Basin (WSB) are displaying two major type facies based on the foraminiferal assemblages. The first one indicates open-marine to outer-shelf conditions, and is represented by numerous bathy-pelagic planktonic foraminiferal species referable to the Radotruncana calcarata, Globotruncana aegyptiaca and the lower part of the Gansserina gansseri Zone (all late Campanian).The second type facies indicates an inner-shelf environment and is represented in the middle-upper part of the Gansserina gansseri Zone (early Maastrichtian) and Racemiguembelina fructicosa (late Maastrichtian) dominated by epi-pelagic planktonic and large benthic foraminifers. Large benthic foraminiferal index species Siderolites calcitrapoides Lamarck and Omphalocyclus macroporus (Lamarck) occur in abundance by the middle–late Maastrichtian. Correlation between planktonic foraminiferal zonation and large benthic foraminiferal zonation is given. An open-marine to outer-shelf environment passed into shallower marine conditions during the late Campanian–early Maastrichtian to late Maastrichtian, then a slight deepening and again shallowing is noticed.

Right Ventricular Mass: Intracardiac Ectopic Thyroid

A 53-year-old woman complained of intermittent angina pectoris for 2 years and was admitted to our hospital to further evaluate cardiac mass. Electrocardiograph(ECG) showed sinus rhythm with incomplete right bundle branch block. Because a primitive cardiac tumor was highly suspected, exploratory surgery was performed. Intraoperative inspection revealed a red mass with a broad base arising from the middle-upper part of the interventricular septum close to the septal leaflet of the tricuspid valve.

Monitoring strata behavior due to multi-slicing top coal caving longwall mining in steeply dipping extra thick coal seam

For studying the strata behavior due to multi-slicing top coal caving longwall mining along-the-strike direction in steeply dipping extra thick coal seams, the shield support pressures of the upper and lower slices of panel 37220 in Dongxia Coal Mine were monitored using the KJ513 dynamic monitoring system. The set up rooms adopted the “horizontal line-arc segment-inclined line” form and used different types of shield supports. The results show that the strata pressure of upper slice panel 37220-1 changed slightly along the strike direction, while along the dip direction it exhibited strong to weak pressure from bottom to top. The first weighting interval of lower slice panel 37220-2 was about 60.8m, and the average periodic weighting interval were about 22.6m. The strata behavior of panel 37220-2 exhibited a spatio-temporal characteristic in that periodic weighting occurred first in the middle-upper part, followed by the middle and upper parts, arc segment, and finally the lower part. During the periodic weighting, the weighting interval and intensity also exhibited strong space characteristics. The average dynamic load coefficient was 1.48 and the maximum lateral load of the side shield was 20–25MPa.