Hydrogeochemistry of the Winder River and adjoining tributaries, Balochistan, Pakistan

Quantitative estimation of ground and stream waters draining through sedimentary rocks of the Pab and Mor ranges (Jurassic-Cretaceous) and the Bela ophiolite has been made. The degree of correspondence among cations and anions has been estimated in order to evaluate their mutual relationships. The abundance of major ions is interpreted to be related to bedrocks and climatic conditions, which may contribute to the genetic affiliation. The log TDS and Na/Na Ca ratio reflected supremacy of weathering of rocks with some influence of evaporation. Ionic relationship is exhibited in the form of Stiff diagrams. Patterns of ionic composition revealed high NaCl, medium Ca(HCO3)2 and low MgSO4. Piper diagram has been used to classify the hydrofacies. The important hydrogeochemical parameters have been estimated for assessment of groundwater quality for domestic purposes in accordance to WHO. Irrigation water qualities have been evaluated in terms of EC, SAR, RSC, ESP and pH.     

川中广安地区上三叠统须家河组岩相组合与沉积特征

根据露头剖面、钻测井资料,分析和总结了川中广安地区上三叠统须家河组(T3x,原称香溪群)的岩相组合、沉积特征及有利储层评价。研究区内须家河组可识别出11种岩相类型、7种岩相组合。川中广安地区在须家河组沉积时期,主要发育了湖泊沉积体系和3个三角洲沉积体系,三角洲砂体以三角洲平原辫状河道与三角洲前缘水下分支河道微相的正韵律砂体叠置发育为特征,三角洲体系中的主干河道叠置带明显控制了有利储层的平面分布,三角洲平原-前缘的过渡区为最有利储层的发育区。     

Sedimentology and depositional environments of the Maastrichtian Patti Formation, southeastern Bida Basin, Nigeria

The Maastrichtian Patti Formation, which consists of shale - claystone and sandstone members, constitutes one of the three Upper Cretaceous lithostratigraphic units of the intracratonic southeastern Bida Basin, in central Nigeria. Well exposed outcrops of this formation were investigated at various locations around the confluence of the Niger and Benue Rivers. The lithostratigraphic sections were measured and their peculiar sedimentological features such as textures, physical and biogenic sedimentary structures, facies variations and associations were documented and used to interpret the depositional environments and develop a paleogeographic model. Some selected representative samples of the sedimentary depositional facies were also subjected to grain size analysis.Three shoreline sedimentary depositional facies composed of shoreface, tidal channel, and tidal marsh to coastal swamp facies were recognized in the study area. Continental sedimentary depositional facies such as fluvial channel, swamp, and overbank were also documented. The sandstones of the shoreface and tidal channel facies are medium- to coarse-grained, moderately sorted (standard deviation ranges from 0.45–1.28 averaging 0.72), and quartzarenitic. The fluvial channel sandstone facies are coarse- to very coarse-grained, mostly poorly sorted (standard deviation ranges from 0.6–1.56 averaging 1.17), and subarkosic. Typical sedimentary structures displayed by the shoreface and tidal channel facies include burrows, clay drapes, hummocky and herringbone cross stratifications, whereas the fluvial channel sandstone facies are dominated by massive and planar cross beddings. The tidal marsh to coastal swamp shales and ferruginised siltstone facies are fossiliferous and bioturbated, whereas the nonmarine swamp siltstones contain vegetal imprints and lignite interbeds. The overbank claystone facies are massive and kaolinitic.In the study area, a regressive to transgressive model is proposed for the Patti Formation. This model correlates with stratigraphically equivalent sediments of the Ajali and Mamu Formations in the adjacent Anambra Basin to a great extent.     

Facies analysis and depositional environments of the OligoceneeMiocene Asmari Formation,Zagros Basin,Iran

The Asmari Formation(a giant hydrocarbon reservoir)is a thick carbonate sequence of the Oligocenee Miocene in the Zagros Basin,southwest of Iran.This formation is exposed at Tang-e-Lendeh in the Fars interior zone with a thickness of 190 m comprising medium and thick to massive bedded carbonates.The age of the Asmari Formation in the study area is the late Oligocene(Chattian)eearly Miocene(Burdigalian).Ten microfacies are defned,characterizing a gradual shallowing upward trend;the related environments are as follows:open marine(MF 8e10),restricted lagoon(MF 6e7),shoal(MF 3e5),lagoon(MF 2),and tidal fat(MF 1).Based on the environmental interpretations,a homoclinal ramp consisting of inner and middle parts prevails.MF 3e7 are characterized by the occurrence of large and small porcelaneous benthic foraminifera representing a shallow-water setting of an inner ramp,infuenced by wave and tidal processes.MF 8e10,with large particles of coral and algae,represent a deeper fair weather wave base of a middle ramp setting.     

Geochemical stream sediment survey in Winder Valley, Balochistan, Pakistan

A pilot scale geochemical survey of sediments from the Winder Stream (SW Pakistan) and its tributaries was carried out. The Winder Stream mainly receives sediment from the southern extensions of the Mor and Pab Ranges in the District of Lasbela (Balochistan). In these two mountain ranges, rocks from Jurassic to Cretaceous age are exposed. Rocks of the Ferozabad Group comprise of carbonates and siliciclastics of Lower–Middle Jurassic age and occupy the dominant part of the Mor Range. These strata host syngenetic and epigenetic Zn–Pb–Ba mineralizations of Stratiform Sediment-Hosted (SSH) and Mississippi Valley Type (MVT) deposits.Quantitative estimates of mobile and immobile elements were made from active stream sediments of the Winder stream and its tributaries. The samples were analyzed for Ag, Zn, Pb, Cu, Ni, Co, V, Mn, Fe and Ba using atomic absorption spectroscopy. The abundance of these elements is discussed in relation to local geological conditions such as bedrock, climate, weathering, mobility and pH of the dispersing waters. A number of Zn anomalies have been distinguished in the study area. Kharrari (Zn, 360 ppm), Sand (Zn, 340 ppm) and Draber (Zn, 210 ppm) are demarcated as new areas for Zn mineralization. The present study also indicates prospects of Ag, Cu and V in the rocks of the Mor Range.Relationships between various elements have been identified from scattergrams and reflect genetic associations. Whereby the positive correlation between Cu–Zn (0.55, n=18) and Cu–Pb (0.63) is related to possible sulphide mineralization.     

Palynomorph and palynofacies indications of age, depositional environments and source potential for hydrocarbons: Lower Cretaceous Zubair Formation, southern Iraq

Assemblages of miospores and dinoflagellate cysts encounterd in core samples three boreholes drilled in southern Iraq an Aptian-mid Albian age-range for the Zubair Formation, the largest oil reservoir in southern Iraq and neighbouring Kuwait. Four types of palynofacies have been identified, and are interpreted to indicate delta top swamp and marsh, delta front, prodelta and marine platform environments respectively. Amorphous matter comprises more than 50% of the organic component of some of the palynofacies in the upper part of the Zubair Formation. The rocks with which they are associated are highly rated as a potential source of liquid hydrocarbons. Those deposits yielding less than this (down to 12%) are considered to have moderate potential.     

Biogeochemical Prospecting of Sulphide Minerals in Winder Valley, Balochistan, Pakistan

Abstract: The Mor Range is mountainous terrain in southern Balochistan dominantly occupied by exposures of rocks of the Ferozabad Group which is comprised of Lower‐Middle Jurassic carbonates and siliciclastics. This group contains syngenetic and epigenetic Zn–Pb–Ba mineralization classified as Stratiform Sediment‐Hosted (SSH) and Mississippi Valley Type (MVT) deposits. Three important flora of the Saharo–Sindian, phytogeographical region of Pakistan, namely Tamarix aphyl–la, Salvadora oleoides and Acacia arabica have been studied as a mineralization prospecting tool. Samples of these species were collected from Winder Valley adjoining the Mor Range to prospect for new areas of mineralization, besides the known sulphide deposits. This study revealed the Draber, Thorar, Raj, Mithi and Kanrach localities as new prospect. Quantitative estimation of biophile elements (Zn–Cu–Pb) from the three species was made. A number of new Zn, Cu and Pb anomalies were distinguished in the area. The variation in the constituents of these species from different localities possibly varies with nature and distance from bedrock, mobility, climate, average abundance in the plant ash and exclusion mechanism of the flora. Acacia arabica with deep penetrating roots shows the best results and could be used to delineate new horizons of mineralization. In these species Zn and Cu are relatively concentrated whereas Pb shows limited enrichment. Lead therefore is the element best suited for pinpointing the mineralization owing to its relatively less mobile character. Relationships among Zn–Cu–Pb have been established using scattergrams and triangular variation diagram, which also demonstrate their genetic affiliation. Statistical analyses, such as determination of mean, mode, median, standard deviation, and coefficient of correlation, were also made to improve the raw geochemical data. These biogeochemical methods appear to be suitable in arid climate of Balochistan, if proper attention is paid to species selection.     

川南威远—泸州页岩气井区奥陶系顶部观音桥组岩相和沉积环境

上扬子地区四川盆地南部威远—泸州地区上奥陶统凯迪阶五峰组和志留系底部兰多维列统龙马溪组黑色笔石页岩沉积于滞留缺氧海底且富含有机质,是页岩气的主产层位,介于五峰组和龙马溪组之间的奥陶系顶部赫南特阶观音桥组通常是含腕足类以及三叶虫的灰岩沉积,其化石组成是冈瓦纳冰川事件最盛期在低纬度陆表海区的产物,岩石学微相特征研究能进一步诠释当时海底沉积环境。本文根据威远地区的W2、W4H10井,泸州地区的L2井、L4井、L5井、L6井、L7井、L8井、L9井观音桥组微相鉴定识别生物多样性,除常见的Hirnantia腕足动物群、三叶虫Dalmanitina等壳相化石外,还出现海百合、腹足类Homotoma、双壳类、海绵动物碎片和虫管遗迹化石Chondrites（丛藻迹）,其化石组成记录了该层位的生物多样性。观音桥组沉积时该区海底富氧环境有利于底栖动物生存,远岸区海底水动力弱,化石粒度偏细且部分化石破碎程度高,未见大量复体珊瑚和钙藻等典型暖水区化石,反映出远岸相观音桥组海底水温可能偏低。     

The Cambrian Araba Formation in northeastern Egypt: Facies and depositional environments

The Cambrian Araba Formation exposed in Gabal El Zeit and in the Sinai Peninsula unconformably overlies Precambrian basement rocks, and is in turn overlain unconformably by the Ordovician Naqus formation. The Araba Formation has been subdivided into three informal lithologic units: lower, middle and upper, from field observations. Seven sedimentary facies assignable to three facies associations (fluvial, tidal and coastal to open marine) are recognized within the Araba Formation. The lower unit comprises two main facies: matrix-supported conglomerate (facies-A) in the south (Gabal Araba and Wadi Feiran) and interbeds of granulestone and sandstone (facies-B) in the north (Gabal Dhalal and Taba) deposited in fluvial conditions. The middle unit includes four facies: cross-bedded sandstone (facies-C), thin laminated sandstone (facies-D), burrowed-massive sandstone (facies-E) and rhythmically bedded sandstone–mudstone (facies-F) deposited mainly under tidal conditions in the coastal zone. The upper unit consists mainly of interbeds of burrowed mudstone-siltstone, with Skolithos, probably deposited in open marine environment. The sequence records the southward transgression of the Tethys Ocean over a horst and graben system developed in the late Precambrian on the northern margin of the Arabo-Nubian continent.     

Sedimentology and depositional environments of the Ordovician Umm Sahm Sandstone Formation in southern Jordan

The Ordovician Umm Sahm Sandstone Formation of Jordan comprises approximately 200-m-thick succession of fluvial quartzarenites with subordinate claystone and siltstone lithologies of shallow marine conditions. The Umm Sahm Formation is characterized by its dark brown color, frequent jointing, and steep scarps. The Umm Sahm Formation is bounded by the marine claystones of Hiswah Formation at the top and the fluvial sandstones of the Disi Formation at the bottom. The Umm Sahm Formation is composed of two main facies: fluvial facies and tidal facies. The fluvial facies constitutes about 93% of the total thickness. The lower few meters of the succession passes upward from the Disi Sandstone Formation into similar massive white sandstone facies exhibiting similar white color, fine- to coarse-grained sandstone, with round-shaped pebbles. Trough and planar cross-bedding show a northwest unidirectional palaeocurrent trend. Light brown colored quartzarenites similar to those of the Cambrian Umm Ishrin Sandstone Formation are most common in the upper part of the succession. The tidal facies occupies three intervals in the middle part of the succession. It is composed of laminated and thin-bedded sandstones, siltstones, and claystones. They are rippled and varicolored with abundant trace fossils (Cruziana, Harlania, ruzophycus). The presence of hummocky cross stratification indicates the earliest short-lived tempestite conditions during the Paleozoic erathem of Jordan. The first appearance of Graptolites in the Ordovician rocks of Jordan was recorded during this study in the tidal facies of the Umm Sahm Formation. The vertical arrangement of both fluvial and tidal facies indicates three successive short-lived transgressions and regressions. These marine incursions indicate the successive shoreline advances of the Tethys Ocean, which was located northward, and inundated the southern braid plain. The three short-lived transgressive events took place, and the Tethys marine margin was displaced southward, giving rise to deposition of tidal facies in an open coast tidal flat. Following the transgressive events, renewed progradation and strandline retreat took place, fed by large amounts of siliciclastics derived from the continent and transported by braided streams across the intertidal zone.     

Biostratigraphy, depositional environments, and diagenesis of the Tamana Formation, Trinidad: a tectonic marker horizon

The Tamana Formation of the Central Range of Trinidad was studied in order to determine its importance in the stratigraphical and structural development of north-eastern South America. Biostratigraphical, petrological and mineralogical data, combined with field mapping show that the Tamana sediments are composed of five distinct lithofacies: inner to outer shelf, burrowed shaley mudstone; outer shelf, Fe-rich sandy limestone; submarine channel, conglomeratic mudstone; middle shelf to nearshore, algal-foram packstone/grainstone; and intertidal to nearshore, algal-stromatolite-coral boundstone with coral bioherms. Maximum thickness of the Tamana Formation is 244 m. Deposition of the Tamana limestones occurred between the Praeorbulina glomerosa (latest early Miocene) and Globorotalia fohsi robusta (middle part of the middle Miocene) planktonic foraminiferal zones, and in a more continuous trend than is seen in the current outcrop belt. Detailed biostratigraphy shows that the Tamana Formation is a facies equivalent of the shallow- and deep-water shales of the Brasso Formation, and the deep water turbidites of the Herrera Member of the Cipero Formation. The early diagenetic history of the Tamana limestones was dominated by the precipitation of authigenic glauconitic smectite, and the dissolution of skeletal grains and carbonate matrix. Late burial diagenesis was dominated by the precipitation of illite and illite/smectite. Comparative mineralogy and textural analyses indicate a minimum range of burial depth for the Tamana Formation at 800–1500m, with a maximum of 2400 m. Alteration of Fe-bearing minerals to geothite and late fracturing occurred during post-Pliocene tectonic uplift and unroofing of the Central Range. The Tamana Formation sediments can be used as a structural and stratigraphical event marker within the Late Tertiary geological history of Trinidad. These units record a phase of the tectonic interaction between the Caribbean and South American plates in the south-eastern Caribbean, and reflect the onset of contractile deformation in the Central Range.     

论两种二叠-三叠系界线

<正> 近年来许多地质学家围绕着二叠-三叠系界线的划分问题做了大量的工作,关于二叠-三叠系之间界线定义,尚未取得一致意见。目前议论较多的主要是两条界线:1.Otoceras层之底——传统界线     

Isotope geochemistry, petrology and depositional environments of the diatomite-dominated Tripoli Formation (Lower Messinian), Sicily

ABSTRACT The Tripoli Formation (Lower Messinian) in Sicily includes diatomites irregularly alternating with marl and carbonate beds and lies, stratigraphically, between the Tortonian pelagic marls and the evaporitic Calcare di base. The relationships between mineralogy, textural features and oxygen-carbon isotopic compositions of carbonate components point to a wide variability of depositional conditions and suggest that Tripoli sedimentation occurred in small basins characterized by periodic and marked restriction from the open sea.
The isotopic values of calcite and dolomite in the diatomites suggest an evolution from normal marine towards more restricted environments. Evaporating conditions are also indicated by the occurrence of anhydrite, length-slow chalcedonic quartz and moulds of gypsum. In a more advanced stage, the precipitation of heavy δ¹⁸0 dolomite in the interstitial pores of fossil-poor diatomites denotes an environment with highly evaporated water. Mixing of meteoric and marine waters, on the other hand, might have favoured the precipitation of a dolomite characterized by relatively low δ¹⁸0 and δ¹³C values.
The deposition of marl and carbonate beds alternating with or overlying the diatomites took place in an environment with highly evaporated marine waters on the basis of δl¹⁸O values of dolomite (up to + 9.10‰) and aragonite (up to + 5.83‰), occurrence of evaporitic minerals and lack of fossils. The presence at these levels of calcite with extremely negative δ¹³C values (down to - 38.40‰), filling gypsum moulds, suggests activity of sulphate-reducing bacteria. Some aragonitic marls, however, bear evidence of deposition in relatively normal marine conditions.     

Geology and Genesis of Barite Deposits of Lasbela and Khuzdar Districts, Balochistan, Pakistan

Abstract: Geology and genesis of the sediment-hosted barite deposits in the Lasbela and Khuzdar districts of Balochistan, Pakistan have been studied and described. Hot solutions generated in rifting environments during the initial stage of separation of the continental crustal block related to the Gondwanaland fragmentation subsequently reposed in Jurassic rocks, most probably played an important role on barite formation.
Paragenetic relationships indicate that the period of barite mineralization was distinctly later than that of zinc-lead sulphide mineralization in the Lasbela and Khuzdar districts. The barite deposits occur on top and in peripheral to the zinc-lead sulphides. The earliest barite mineralization took place in the clastic rock sequence of the lower Spingwar Formation as cross cutting veins. Younger mineralization as stratabound-replacement type occurred within the platform limestones of Loralai Formation, just above the Spingwar Formation. The youngest mineralization as stratiform is hosted within black shales, mudstones and argillaceous limestones of Anjira Formation at the top of Loralai Formation. In the light of the evidences gathered from field and laboratory investigations a genetic model has been deduced.     

Lithofacies and environments of Bed I,Olduvai Gorge,Tanzania

Bed I in Olduvai Gorge spans the interval from about 1.7 to 2.0 m.y.a., and all evidences of hominid activity at Olduvai are within the latter half of this period. Bed I was deposited in a closed basin approximately 25 km in average diameter, and it can be subdivided into five lithologically different but partly time-equivalent rock assemblages, or lithologic facies, each of which was deposited in the same geographic environment or closely related series of environments. These lithofacies comprise lake deposits, lake-margin deposits, alluvial-fan deposits, alluvial-plain deposits, and lava flows.Alluvial-plain deposits form the lowermost part of Bed I, and they presumably interfinger northeastward with lake deposits in an area not now exposed. Discharge of the lavas diplaced the lake westward to a position it occupied through the latter half of the deposition of Bed I. The lake fluctuated greatly in salinity, level, and extent, and at times of low level it was highly saline and generally ranged between 7 and 10 km in average diameter. At times of high level it was as much as 15 km in diameter and was relatively fresh, at least along its southeastern margin. The lake-margin deposits accumulated on the zone of relatively flat terrain that was flooded at times of high level. Lake-margin deposits interfinger eastward with deposits of an alluvial fan of pyroclastic materials produced in an explosive phase of the volcano Olmoti. The climate at the time of Bed I was relatively dry although somewhat wetter than the present climate in the same region today.     

Lithofacies and depositional characteristics of gas shales in the western area of the Lower Yangtze,China

The Lower Yangtze is considered as a potentially productive shale gas area in China, but only limited research has thus far been carried out there. On the basis of a detailed investigation of fourteen outcrops, eight lithofacies in the Hetang Formation (510–541 Ma), the Gaojiabian Formation (430–443.4 Ma), the Gufeng Formation (270–281 Ma) and the Dalong Formation (252–263 Ma) have been identified: silicalite, siliceous non‐calcareous mudstone, siliceous shale, carbonaceous shale, calcareous mudstone, silty–shaly interlaminated mudstone, siltstone and limestone. Three types of fossils were also found in the four formations: sponge spicules, radiolarians and graptolites. Moreover, four key outcrops of the fourteen were suitable for more additional detailed analyses and interpretation of their depositional environments and plausible sequence of the stratigraphic system tracts. As a result, the four potential shale gas formations were all divided into third‐order sea‐level sequences. Every third‐order sequence was further divided into four system tracts, corresponding to an early transgressive system tract (ETST), a late transgressive system tract (LTST), an early highstand system tract (EHST) and a late highstand system tract (LHST). On the basis of the interpretation of the lithofacies and depositional environments in the western area of the Lower Yangtze, sediments can be related to hydrothermal and biological processes, terrigenous clastic input and calcium compensation. These processes were interpreted to occur in a sequential order that we divide into three stages. The ETST period was the first stage, in which hydrothermal upwelling from the open ocean produced a siliceous lithological combination. During the second stage corresponding to the LTST + EHST, our results suggest that some biological communities in the stable deep water provided plenty of organic‐rich matter. The LHST period was the third stage, in which terrigenous clastic material was deposited close to the land, and some carbonate sediments began appearing near the platform. Copyright © 2014 John Wiley & Sons, Ltd.     

宿州地区震旦系望山组主要沉积类型及其形成环境分析

安徽省宿州地区震旦系望山组因碳酸盐岩中含有大量形态复杂的微晶碳酸盐脉体(即臼齿构造)而得到了广大研究者的深入研究.该组中除含有碳酸盐岩、泥岩和页岩等正常海相沉积外,还记录了生物沉积和特征明显的地震、风暴、海啸等事件沉积过程和风化壳残积,沉积环境复杂多变.该组碳酸盐岩中臼齿构造、缝合线构造、滑塌构造、交错层理、冲刷构造等沉积构造具有较好的事件沉积指示意义.该组事件沉积的特征表明,当时频繁的地壳活动是造成事件沉积及复杂沉积环境的主要原因.     

Biogeochemical evaluation of Nannorrhops ritchiana： A Mg-flora from Khuzdar, Balochistan, Pakistan

Nannorrhops ritchiana （ Mazari Palm） is a distinctive flora growing in the Saharo-Sindian region. It is well distributed on the ultramafic soil, derived from the Bela Ophiolite in the Khuzdar District, Balochistan, Pakistan. Quantitative estimation of Ca, Mg, Fe and Ni in soil and plant ash has been carried out. The constituents of plant ash have been discussed in relation to soil chemistry, pH, climate, mobility, average abundance in plant ash and exclusion mechanism of the flora. Relationship among Ca, Mg, Fe and Ni has been established using scattergrams to evaluate the biogeochemistry of the plant. High contents of Mg and high coefficient of biological absorption allow it to be classed as Mg-flora. Both Ca and Fe appeared to be antagonistic to Mg. The metal assemblage of N. ritchiana nicely reflected the nature of the bed rock as being serpentinized ultramafic, and its corresponding soils. Good exclusion mechanism of N. ritchiana did not allow it to absorb high Ni from the soil. Relatively high concentrations of Ni in N. ritchiana from the Baran Lak area can be used to localize Ni-mineralization in the study area. Statistical analyses, such as minimum, maximum, mean, mode, median, standard deviations, and coefficient of correlation, were also made to improve raw geochemical data and interpretations.     

Sedimentology and depositional environments of the Lund Diamicton, southern Sweden

The Lund Diamicton (earlier named Lund Till) in SW Skåne, S. Sweden, is a glacioaquatic sediment consisting of clay and massive and laminated diamictons. It is characterized by clasts derived from the Baltic depression and its depositional history can be summarized as follows: After deglaciation, large fields of stagnant ice remained in the area and a periglacial land surface with ice-wedge polygons and wind-abraded clasts was developed in ice-free areas. A transgression followed and a clay/diamicton sediment was deposited, partly on top of stagnant ice and against a coastal barrier of stagnant ice along large parts of the basin boundary. This sediment is the Lund Diamicton. The main depositional processes were: fall-out of clay from suspension, sediment gravity flow from stagnant ice and icebergs and rain-out of debris from floating icebergs. The unit was extensively deformed by escaping pore water, loading, flow and due to melting of buried ice. The Lund Diamicton is the equivalent in this area of the classical 'Low Baltic till', which has been interpreted as a basal till deposited by the 'Low Baltic ice stream'. The present study concludes that this unit is instead a glacioaquatic sediment deposited during a transgression in the Öresund area. Its boundary represents the highest coastline and not the margin of a glacier.