Characteristics and origins of middle Miocene mounds and channels in the northern South China Sea

Numerous elongated mounds and channels were found at the top of the middle Miocene strata using 2D/3D seismic data in the Liwan Sag of Zhujiang River Mouth Basin(ZRMB)and the Beijiao Sag of Qiongdongnan Basin(QDNB).They occur at intervals and are rarely revealed by drilling wells in the deepwater areas.Origins of the mounds and channels are controversial and poorly understood.Based on an integrated analysis of the seismic attribute,palaeotectonics and palaeogeography,and drilling well encountering a mound,research results show that these mounds are dominantly distributed on the depression centres and/or slopes of the Liwan and Beijiao sags and developed in a bathyal sedimentary environment.In the Liwan and Beijiao sags,the mounds between channels(sub)parallel to one another are 1.0–1.5 km and 1.5–2.0 km wide,150–300 m and 150–200 m high,and extend straightly from west to east for 5–15 km and 8–20 km,respectively.Mounds and channels in the Liwan Sag are parallel with the regional slope.Mounds and channels in the Beijiao Sag,however,are at a small angle to the regional slope.According to internal geometry,texture and external morphology of mounds,the mounds in Beijiao Sag are divided into weak amplitude parallel reflections(mound type I),blank or chaotic reflections(mound type II),and internal mounded reflections(mound typeⅢ).The mounds in Liwan Sag,however,have the sole type,i.e.,mound type I.Mound type I originates from the incision of bottom currents and/or gravity flows.Mound type II results from gravity-driven sediments such as turbidite.Mound typeⅢis a result of deposition and incision of bottom currents simultaneously.The channels with high amplitude between mounds in the Beijiao and Liwan sags are a result of gravity-flow sediments and it is suggested they are filled by sandstone.Whereas channels with low-mediate amplitudes are filled by bottom-current sediments only in the Beijiao Sag,where they are dominantly composed of mudstone.This study provides new insights into the origins of the mounds and channels worldwide.

Characteristics of termite mounds and associated Acrisols in the coastal savanna zone of Ghana and impact on hydraulic conductivity

Characteristics of termite mounds and associated Rhodic Acrisol and Haplic Acrisol in the coastal savanna zone of Ghana and their impact on hydraulic conductivity were assessed. The texture of the mounds was sandy clay in contrast to the sandy clay loam of the surface soils. Translocation of fine to medium sized soil materials influenced the relatively higher bulk density (>1.60 Mg/m3) and contents of organic carbon, nitrogen and exchangeable bases in the mounds. Kaolinite was the dominant clay mineral with pH values generally below 5.3 in all the soils reflecting the weathered tropical soil environment. Dispersion ratio values, which were 0.5 for the surface soils, indicated greater stability of the mound due to aggregate cementing action by the termites. Estimated mound density was about 120 mounds per ha, which tied in with known groundwater reserves at the study sites. Majority of the mounds exhibited a cone-shaped morphology with heights varying between 3.05-4.00 m in the Rhodic Acrisol and 2.05-4.20 m in the Haplic Acrisol with corresponding estimated total mass of 96,361 kg and 54,910 kg per 1000 m2 land area. These estimates represented a large amount of material relative to the 25,000-26,000 kg of surface soil material within the same unit area. The K in the surface soils ranged from 3.3 x 10-5 to 5.0 x 10-5 m/s while the value for the mound was ≤0.5 x 10-5 m/s. Lower porosity, θ;the effect was more pronounced when the mound was applied on the soil surface. Improvement in water retention and nutrient availability to plants and prevention of leaching to avoid groundwater contamination are some of the positive attributes of this study.

The Effect of Catena Position on Greenhouse Gas Emissions from Dambo Located Termite (<i>Odontotermes transvaalensis</i>) Mounds from Central Zimbabwe

Methane (CH4), carbon dioxide (CO2) and nitrous oxide (N2)O) are greenhouse gases (GHGs) which cause global warming. Natural sources of GHGs include wetlands and termites. Previous studies have quantified GHG emissions from upland termites and no study has reported GHG emissions from seasonal wetlands (dambo) located termite mounds. The objective of this study was to evaluate the effect of dambo catena position on termite mound distribution and GHG emissions. It was hypothesized that mound density and GHG emissions from Odontotermes transvaalensis mounds, vary with catena position. The evaluated catena positions were margin, mid-slope, lower slope and bottom. Mound density was significantly lower in the bottom when compared to the other catena positions. The mean GHG fluxes were 88 μg m2 hr-1, 0.78 mg m2 hr-1 and 1361 mg m2 hr-1 for N2) O, CH4 and CO2 respectively. Fluxes varied with catena position and were 0.48, 0.72, 1.35 and 0.79 mg m-2 hr-1 for CH4 , and 1173.7, 1440.7, 1798.7 and 922.8 mg m-2 hr-1 for CO2 in the margin, mid-slope, lower slope and the bottom catena position respectively. For N2) O, there were no significant differences between catena positions. It was concluded that dambo located Odontotermes transvaalensis termite mounds are an important source of GHGs, and emissions varied with catena position for CO2 and CH4.

Composite Stratigraphy of the Sailinhudong Group and Ore-bearing Micrite Mounds in the Bayan Obo Deposits,Inner Mongolia,China

Based on studies of sequence stratigraphy, event stratigraphy, biostratigraphy and lithostratigraphy, it is concluded that the Sailinhudong Group is a part of the Bayan Obo Group. Some trilobite fragments are first found in thin sections of the rock from the lower part of the Sailinhudong Group and some Ordovician acritarchs and chitinozoans are also found in this group. A formationa unit of carbonate seismites is first recognized in the upper part and a huge micrite mound is first identified at the top. Dolomite, the host rock of the super giant Bayan Obo Fe-Nb-REE deposits, is neither an igneous carbonatite nor a common bedded sedimentary carbonate, but a huge micrite mound. It has the same macroscopic characters as the micrite mounds at the top of the Sailinhudong Group, which suggests that they should be of the same horizon. According to the fossils, the Sailinhudong and Bayan Obo Groups should be of the Early Palaeozoic rather than the Middle Proterozoic. The new discovery and new idea will throw light on the explanation of the genesis of the supergiant Bayan Obo Fe-Nb-REE deposits.

Deformation monitoring and analysis at two frost mounds during freeze–thaw cycles along the Qinghai–Tibet Engineering Corridor

This paper presents various deformation-monitoring technologies employed to monitor the frost heave and thaw settlement of two mounds along the Qinghai–Tibet Engineering Corridor(QTEC), China. The QTEC is known as a critical infrastructure and passage connecting inland China and the Qinghai–Tibet Plateau(QTP). Three technologies—global navigation satellite system(GNSS), terrestrial laser scanning(TLS), and unmanned aerial vehicle(UAV)—were used to estimate the freeze/thaw–induced 3D surface deformation of two frost mounds. Our results showed that (1) the two frost mounds exhibited mainly thaw settlement in thawing periods and frost heave in the freezing period, but frost heave dominated after repeated freeze–thaw cycles;(2) different zones of the mounds showed different deformation characteristics;(3) active-layer thickness(ALT) and elevation changes were highly correlated during thaw periods;(4) integrated 3D-measurement technologies can achieve a better understanding and assessment of hazards in the permafrost area.

Reservoir Potential of Silurian Carbonate Mud Mounds in the Southern Sichuan Basin,Central China

Lower Silurian mud mounds of the Shinuilan Formation, located in the southern Sichuan Basin, China, have developed in open shelf settings in deeper water than shallow-water reef-bearing limestones that occur in the region. An integration of the outcrop, drill data and seismic profiles show that contemporaneous faults have controlled the boundary and distribution of the sedimentary facies of Lower Silurian rocks in the southern Sichuan Basin. Mounds appear to have developed in the topographic lows formed by synsedimentary faulting, on the sheff of the Yangtze Platform. Average mound thickness is 20 m, maximum 35 m. Mounds are composed mainly of micrite, possibly microbially bound, and are overlain by shales. Mound tops are preferentially dolomitized, with the Mg^2＋ source probably from the clay content of the mound-top carbonate. Microfacies analysis and reconstruction of the diagenetic history reveal that the mound tops have higher porosity, and are gas targets; in contrast, mound cores and limbs show pores filled by three generations of calcite cement, and therefore have a low gas potential.

Spatial confirmation of termite mounds as Bio-geo indicator for groundwater occurrences using ground magnetic survey: A case study from Perambalur Region of Tamil Nadu, India

Termite mounds are conventionally surmised as one of the best bio-geological indicator for groundwater occurrence in places where they inhibit.Ground magnetic survey was carried out to prove the assumption about termite mounds as an important indicator for groundwater exploration.Occurrences of 18 Termite mounds were mapped using handheld GPS to identify the suitable trend for magnetic survey.After considering all the criteria such as power lines,fences and fracture system,termite mound 2,12 and 18 were selected in the NNE-SSW trend,and the ground magnetic survey was conducted in ESE-WNW direction which is perpendicular to the trend of the termite mounds using Proton Precession Magnetometer.Totally,99 samples were collected with 5 m sampling interval and 50 m profile interval over an area of 22500 sq.m.The magnetic values varied from–7363 nT to 898 nT with the mean of–331 nT.Processed map of reduction to Equator indicates the presence of NNE-SSW and WNW-ESE magnetic breaks.Analytical signal map designated the presence of magnetic low in the WNW-ESE direction which coincides spatially with the magnetic breaks.The magnetic profile lines have also brought to light the structurally weak zones.Causative body depth range was estimated using power spectrum and Euler method which are from 120 m to 40 m and<20 m to>100 m,respectively.The present study appreciably brings out the spatial relationship between the termite mounds and the hydro-fractures.This confirms the assertion with regard to termite mounds as an effective tool for groundwater exploration.

Middle and Late Devonian microbial carbonates,reefs and mounds in Guilin,South China and their sequence stratigraphic,paleoenvironmental and paleoclimatic significance

Microbial precipitation of calcium carbonate has played a major role in formation of carbonate platforms since the Archean. Also, microbial carbonates and biologically induced ce-ment are important contributors to reef framework volume and rigidity in carbonate platform systems during times of significant environmental change including transgressive events in plat-form environments and the recovery interval following the major biotic crisis. The stratigraphic distribution of different types of microbial carbonates appears to vary within the sequence strati-graphic framework. Reefs and mounds within the Late Devonian carbonate platforms in Guilin, South China are formed primarily by calcimicrobes and biologically induced cement, representing the microbe-dominated and characteristic carbonate buildups within a reefal ecosystem that nearly all reef-building metazoans were absent after the Frasnian/Famennian biotic crisis. Mi-crobial community and microbialite seem to be linked with specific palaeoenvironment and pa-laeoclimate, suggesting that they could be used as indicators of environmental change and biotic events.

Role of calcimicrobes and microbial carbonates in the Late Carboniferous(Moscovian) mounds in southern Guizhou,South China

Various microbial fabrics characterize late Moscovian mounds in Houchang Town,southern Guizhou,South China.The dominant components of the mounds are microbial boundstones with stromatolitic structures,irregular oncoid-like forms,and wrinkle structures.Calcimicrobes recognized in the mounds include Girvanella,Ortonella,Wetheredella-like,Palaeomicrocodium-like,and some problematic calcimicrobes occurring in deposits between microbial boundstones,in thrombolitic textures,and in some intraclasts.Microbial carbonates are common in the substrate and interior of the mounds,including thrombolitic textures,microstromatolites,microbial ooids,oncoids,irregular encrusted layers,microbial mat debris,and microbial micrite.Calcimicrobes and microbial carbonates played an important role in the construction of the mounds:Girvanella might have contributed as a source of lime mud that formed the mound and stabilized the coral frame;thrombolitic mats could trap and fix sediments and bioclasts,contributing to the stabilization of substrate and mound limestones;and,microbial boundstone,clotted micrite and micritized bioclast could provide a hard substrate for encrusting metazoans(e.g.,bryozoans,Ivanovia).The abundant microbial fabrics in the mounds indicate that microbial activity was widespread in Moscovian reef mounds in southern Guizhou,and this suggests that microbial organisms were the primary mound builders in the study area.

Effects of site preparation methods on soil physical properties and outplanting success of coniferous seedlings in boreal forests

This study assessed the effect of patch scarification and mounding on the physical properties of the root layer and the success of tree planting in various types of forests.This study was conducted on 12 forest sites in taiga forests of the European part of Russia.A total of 54 plots were set up to assess seedling survival;root collar diameter,height,and heigh increment were measured for 240 seedlings to assess growth.In the rooting layer,240 soil samples were taken to determine physical properties.The study showed that soil treatment methods had no effect on bulk density and total porosity in Cladina sites.However,reduced soil moisture was noted,particularly in mounds,resulting in increased aeration.In Myrtillus sites,there were increased bulk density,reduced soil moisture,and total porosity in the mounds.Mounding treatment in Polytrichum sites resulted in reduced soil moisture and increased aeration porosity.In the Myrtillus and Polytrichum sites,patch scarification had no effects on physical properties.In Polytrichum sites,survival rates,heights,and heigh increments of bareroot Norway spruce seedlings in mounds were higher than in patches;however,the same did not apply to diameter.In Cladina and Myrtillus sites,there was no difference in growth for bareroot and containerised seedlings with different soil treatments.Growing conditions and soil types should be considered when applying different soil treatment methods to ensure high survival rates and successful seedling growth.

Hydrodynamic Assessment of A New Nature-Based Armour Unit on Rubble Mound Breakwater for Coastal Protection

This research proposes a novel nature-based design of a new concrete armour unit for the cover layer of a rubblemoundbreakwater. Armour units are versatile with respect to shape, orientation, surface condition details, and porosity.Therefore, a detailed analysis is required to investigate the exact state of their hydraulic interactions and structuralresponses. In this regard, the performance results of several traditional armour units, including the Antifer cube,Tetrapod, X-block and natural stone, are considered for the first step of this study. Then, the related observed resultsare compared with those obtained for a newly designed (artificial coral) armour unit. The research methodology utilizesthe common wave flume test procedure. Furthermore, several verified numerical models in OpenFOAM code areused to gain the extra required data. The proposed armour is configured to provide an effective shore protection as anenvironmental-friendly coastal structure. Thus it is designed with a main trunk including deep grooves to imitate thetypical geometry of a coral type configuration, so as to attain desirable performance. The observed results and ananalytic hierarchy process (AHP) concept are used to compare the hydraulic performance of the studied traditionaland newly proposed (artificial coral) armour units. The results indicate that the artificial coral armour unit demonstratesacceptable performance. The widely used traditional armour units might be replaced by newer designs for betterwave energy dissipation, and more importantly, for fewer adverse effects on the marine environment.

Segmented evolution of Deyang-Anyue erosion rift trough in Sichuan Basin and its significance for oil and gas exploration, SW China

Based on analysis of field survey, drilling and seismic data, the formation and evolution process of Deyang-Anyue erosion rift trough in Sichuan Basin was reconstructed, and exploration areas were divided and evaluated. The results show that:(1) Dengying Formation in and around Deyang-Anyue erosion rift trough varies widely in sedimentary characteristics. The Dengying Formation in the northern part of the erosion rift trough developed deep-water sediments, the Dengying Formation in the northern part of the basin varied gradually from basin to slope, platform margin, and restricted platform, and the Dengying Formation in the middle and southern parts of the trough developed carbonate platform facies.(2) Deyang-Anyue erosion rift trough is formed by extensional rift and karst erosion jointly, the north section of the erosion rift trough is mainly the product of tensile rift, while the middle and south sections are formed by erosion in multi-episodes of Tongwan period.(3) Based on the segmented origins of the erosion rift trough, Dengying Formation in and around it is divided into three exploration fields: lithologic mound and beach bodies at the northern platform margin of the basin, karst mound and beach bodies in the central platform, and karst residual mounds in the central southern trough of the basin, among them, the karst residual mounds in the central southern trough of the basin are a new frontier for natural gas exploration in the basin, and the lithologic mound and beach bodies at the northern platform margin are a new position for increasing the reserves of trillions of cubic meters of natural gas resources in the basin.

Impending Pollution of Betare Oya Opencast Mining Environment （Eastern Cameroon）

Mining resources are offered by the natural milieu and liable to exploitation. Raw materials extracted are essential for jewellery and economy. But in most cases, the environmental impact assessment is disappointing. In this study conducted at Betare Oya, mining residues are directly disposed in the immediate environment without passing through the tailing ponds for treatment, despite environmental laws and standards. Soluble components of matter are slowly dissolved, drained by meteoric water and flowed into tail bay vicinity. Soil and mining residues were sampled in Mari, Mbigala, Mboufa and Bedobo, respectively, four sub-watershed of Lom, the main river of the region. Concentration of nine MTE （metallic trace elements）： As, Cd, Cr, Cu, Co, Ni, Pb, Zn and Hg were determined by ICP-MS （inductively coupled plasma-mass spectrometry）. Highest concentrations of trace and toxic metals in soil and mining residues are： Cr （210 mg·kg-1） 〉 Zn （136 mg·kg-1） 〉 Ni （64 mg·kg-1） 〉 As （34 mg·kg-1） 〉 Cu （30 mg·kg-1） 〉 Pb （25 mg·kg-1） 〉 Co （17 mg·kg-1） 〉 Cd （0.5 mg·kg-1） 〉 Hg （0.1 mg·kg-l）, respectively. These results let assume that it is a risk of environmental pollution and poisoning relative to these elements around Betare Oya opencast mining area, with impact on human health.

Tectonic paleogeography of Late Sinian and its significances for petroleum exploration in the middle-upper Yangtze region, South China

The paleotectonic pattern,lithofacies paleogeographic features,sedimentary evolution and its controlling effects on hydrocarbon accumulation assemblages during the depositional period of the Sinian Dengying Formation in middle-upper Yangtze region were investigated based on outcrops,drilling,log and seismic data.The study shows that,(1)Affected by the breakup of the Rodinia supercontinent,the middle and upper Yangtze areas were in extensional tectonic environment during the depositional period of Dengying Formation.The carbonate platform was structurally differentiated.Intra-platform depressions controlled by syndepositional faults developed,forming a tectonic-paleogeographic pattern of"three platforms with two depressions".(2)During the depositional period of the first and second members of the Dengying Formation,rimmed platforms and intra-platform fault depressions developed in upper Yangtze area and isolated platform developed in middle Yangtze area,and there was the Xuanhan-Kaijiang ancient land block in eastern Sichuan.The depositional period of the third member of the Dengying Formation is the transformation period of tectonic-paleogeographic pattern,when a set of shallow water shelf sediment rich in mud was deposited due to transgression on the background of the eroded terrain formed in EpisodeⅠof Tongwan Movement.The sediment of the fourth member of the Dengying Formation inherited the paleogeographic pattern of the first and second members of the Dengying Formation in general,but the Deyang-Anyue intra-platform fault depression further expanded,and the middle Yangtze platform evolved into two separated platforms.(3)Tectonic-sedimentary differentiation and evolution of carbonate platform in the Sinian gave rise to two types of accumulation assemblages with wide distribution and great exploration potential,which are platform margin and intra-platform.

Do historical maps show the maximal anthropopressure in the Carpathians?

Many landscapes bear the marks of historical land use.These marks can be the basis for a reconstruction of a historical land use structure as some of them are typical of different types of human activity.The aim of this paper is to determine whether Austrian cadastral maps from the 19th century present the image of the most transformed environment in the Western Carpathians as a result of agricultural activity.Land use structure and terrain forms were detected based on Austrian cadastral maps from 1848,airborne laser scanning and field studies.In two of the test areas,the percentage of arable fields was higher among the plots with stone mounds than the percentage among the plots without them.In the third test area,the relationship was reversed.Also,lynchets,terraces and stone walls sometimes occur in plots that were not arable fields in 1848.Thus,the Austrian cadastral maps from 1848 could not reflect the maximal range of arable fields in the Carpathians in the 19th century.However,it is impossible to determine the historical structure of land use precisely.Nevertheless,an inventory of terrain forms can be used to assess land use when historical maps have not preserved or when available maps do not present land use in detail.

Effects of Manual, Cultural, Botanical and Chemical Treatments of Termite Control in Hamelmalo Agricultural College Area

Termites are the most serious pests of field and horticultural crops, forests, and wooden household furniture. In Hamelmalo Agricultural College (HAC) the infestation of termite is very high resulting in great destruction of crop plants and wooden office and dormitory furniture. The devastating attack of termites should be managed by using best and ecofriendly management method. The purpose of the study was to compare the effectiveness of manual destruction of mounds and killing of termite queen and king, chemical chlorpyrifos, seed and leaves extract of neem and Lantana (as separate experiment) and smoke on termite control. Termite mounds were selected randomly inside HAC compound. The materials used were hand hoe, spade, fork, water, 20 L jar and protective clothes. The treatments were replicated three times. The botanical treatments were prepared at 2 L of highly concentrated extracts per 20 L of water each. Chlorpyrifos was applied at 20 ml per 20 L of water. Dried woody plants were used for smoke treatment. Careful digging was done to avoid king escape and queen rupture and they were killed by burning. Among all, the mechanical destruction and killing of king and queen and chlorpyrifos resulted in a complete control of the termite population. Except in the mounds treated by chlorpyrifos, the activity of termite population was very active and they closed the opened galleries immediately after treatment even though there were dead termite castes in all treatments. Living termite castes were counted by taking a medium size spade of broken mound pieces. The highest count was recorded from mounds treated by smoke. After two weeks the queen and king in every treatment mound were cheeked and killed for those who were alive. Except by the chlorpyrifos and manual destruction of mound (king and queen were killed before) all the royal families were alive and killed. Controlling of termite population in the field (outside their mound) is not possible due to the hidden foraging activity of termites, environmental safety from chemicals and the high egg laying potential of the queen. Finding the best alternative to control from their source mound for the mound building termites resulted in effective control of the population by manual destruction of mounds and killing of queen and king and chlorpyrifos. By the side effect of chlorpyrifos to untargeted organisms and the time consuming and laborious method of manual destruction of mounds, selection to the best from these two control measure is almost the same.

Modeling Vegetation Lifeforms Abundance based on <i>Epigeal Termitaria</i>Physiography and Altitude in Tropical Savannah of Katolo Sub-Location, Kisumu County

Termite mounds are major sites of functional heterogeneity in the tropical ecosystems globally;through their prodigious influence on vegetation and soil perturbation. They aid soil aeration, water infiltration and catabolism of vegetative matter into nutrient rich humus. There is no documentation of a model for prediction of vegetation lifeforms with respect to mound basal radii, heights and altitude. Objective of this study was therefore to develop a model for rapid prediction of vegetation lifeforms (trees, shrubs, lianas and grass) abundance based on physiography (basal radii and heights) and altitude of the termite mounds. Study population of the mounds was unknown. Cross sectional research design was used. Saturated sampling was done where sixty accessible termite mounds were studied. Both basal radii and heights of termite mounds were measured using 50 m tape measure or hand-held inclinometer. Altitude data were captured by hand-held Global Positioning System (GPS). Trees, shrubs and lianas were identified visually and counted on the mounds while grass abundance was estimated using 0.3 m by 0.3 m quadrat on every termitarium. Multiple Linear Regressions were done to model vegetation lifeforms abundance based on termite mound basal radius, height and altitude. Results indicated that predicted MLR significantly (p ≤ 0.05) predicted trees, shrubs and lianas but not grass abundance. Predicted trees abundance = -89.2587 + 10.46157 (radius (m)) - 4.96989 (height (m)) + 0.074074 (altitude (m)), predicted shrubs abundance = 19.26065 + 6.780626 (radius (m)) - 6.09157 (height (m)) - 0.00822 (altitude (m)) and predicted lianas abundance = -24.9345 + 5.881659 (radius (m)) - 0.68423 (height (m)) + 0.020729 (altitude (m)). This study demonstrated significant effect of termite mound physiography on vegetation lifeforms abundance as well as developed a model for rapid prediction of their abundance on termite mounds.

Formation mechanisms,potentials and exploration practices of large lithologic gas reservoirs in and around an intracratonic rift:Taking the Sinian-Cambrian of Sichuan Basin as an example

By examining structures,sediments,reservoirs and accumulation assemblages in the Deyang-Anyue rift and its surrounding area,four new understandings are obtained.First,during the initiation period of Deyang-Anyue rift,multiple groups of faults developed in the rift due to the effect of tensile force,bringing about multiple mound and shoal belts controlled by horsts in the second member of the Sinian Dengying Formation;in the development stage of the rift,the boundary faults of the rift controlled the development of mound and shoal belts at the platform margin in the fourth member of Dengying Formation;during the shrinkage period of the rift,platform margin grain shoals of the Cambrian Canglangpu Formation developed in the rift margin.Second,four sets of large-scale mound and shoal reservoirs in the second member of Dengying Formation,the fourth member of Dengying Formation,Canglangpu Formation and Longwangmiao Formation overlap with several sets of source rocks such as Qiongzhusi Formation source rocks and Dengying Formation argillaceous limestone or dolomite developed inside and outside the rift,forming good source-reservoir-cap rock combinations;the sealing of tight rock layers in the lateral and updip direction results in the formation model of large lithologic gas reservoirs of oil pool before gas,continuous charging and independent preservation of each gas reservoir.Third,six favorable exploration zones of large-scale lithologic gas reservoirs have been sorted out through comprehensive evaluation,namely,mound and shoal complex controlled by horsts in the northern part of the rift in the second member of Dengying Formation,isolated karst mound and shoal complex of the fourth member of Dengying Formation in the south of the rift,the superimposed area of multi-stage platform margin mounds and shoals of the second and fourth members of Dengying Formation and Canglangpu Formation in the north slope area,the platform margin mounds and shoals of the second and fourth members of Dengying Formation in the west side of the rift,the platform margin mound and shoal bodies of the fourth member of Dengying Formation in the south slope area,etc.Fourth,Well Pengtan-1 drilled on the mound and shoal complex controlled by horsts of the second member of Dengying Formation in the rift and Well Jiaotan-1 drilled on the platform margin mound and shoal complex of the North Slope have obtained high-yield gas flows in multiple target layers,marking the discovery of a new gas province with reserves of(2-3)×10^(12) m^(3).This has proved the huge exploration potential of large lithologic gas reservoir group related to intracratonic rift.

Spatial correlation of pit and mound topography with canopy gaps in a virgin mixed beech forest, northern Iran

In a reserved forest parcel in a virgin eastern Hyrcanian mixed beech forest,80 ha was surveyed to determine the pit and mound topography,canopy gaps and dead trees.The aim was to investigate the spatial patterns and correlation of pit and mound features with canopy gaps.Seventy-five canopy gaps and 61 pit and mound features were identified.The univariate first order nearest neighbor(R_(CE))and bivariate second order test(Ripley’s K)statistic were applied.R_(CE) statistics highlighted a general aggregation pattern for canopy gaps and pits and mounds,while pits and mounds alone were more clumped.Distances between canopy gaps were 130 m average,whereas distances between pit and mound features and dead trees were 60 and 78 m,respectively.Spatial positive correlation of canopy gaps with pits and mounds were observed with all distances.The result of spatial correlations between canopy gaps with pits and mounds confirmed that windthrows cause micro successions in fallen tree ecosystem-scale correlated with gap phase dynamics in the forest community-scale.

A Study on Some Causes of Rubble Mound Breakwater Failure

Rubble mound breakwater, one of the protection structures, has been widely used in coastal and port engineering. Block stones were first used as its armor layer, and its use was limited to shallow sea areas where there is no large waves. Since the specially-shaped armor unit was developed, the rubble mound breakwater has become the main sort of the protection structures, which can be used in deep water zones where storm sometimes occurs. Owing to severe and complex surrounding conditions, the rubble mound breakwater failure sometimes occurs, thus the study on the causes of failure is of great importance. In the present study some breakwater failures at home and abroad are illustrated and the causes of failure are investigated from the point of view of design, test, construction and maintenance.