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The distribution of macroinfauna was quantified in subtidal, soft-bottom habitats, extending from the estuarine mouth to the tidal head of the Gamtoos—a small, shallow, temperate estuary situated on the south coast of South Africa. Sampling covered the full salinity gradient from fresh to marine waters, and all sediment types from marine sands to fluvial silts. A total of 35 taxa was recorded, of which 22 occurred throughout the year. Species richness and diversity declined from the seawater-dominated mouth region toward the fresh water section at the tidal head of the estuary. Sediment type generally bore no clear relation to biotic diversity. A marked drop in salinity between winter and summer sample series (Δ 0.2‰ to 24‰) coincided with a reduction of mean macrofaunal density by 70%, a more seaward relocation, and a compression of axial ranges of most taxa. Numerical classification and ordination of faunistically similar regions and of co-occurring species delineated four habitat zones along the longitudinal axis of the estuary which harbour four distinct macrofaunal assemblages: 1) A tidal inlet area with salinities close to seawater; clean, coarse, marine sands, rich in CaCO3 harbour a stenohaline fauna normally found on adjacent, marine sandy beaches. 2) In the lower reaches, where fine, fluvial silts of high organic content prevail, euryhaline polychaetes dominate the macrozoobenthic community; bottom salinities in this zone seldom dropped below 25‰ 3) The middle reaches, characterized by oligohaline- to polyhaline waters, stretch over sandy sediments of intermediate carbonate, silt, and organic fractions; the fauna comprises typical estuarine forms, which occurred throughout most of the estuary except at its seaward and landward limits. 4) The upper reaches encompass the limnetic waters near the tidal head of the estuary with sediments in this zone being composed mostly of coarse, clean sands, low in CaCO3; the macrobenthos in this region is dominated by taxa of freshwater origin, which generally do not penetrate seaward beyond the oligohaline waters, and by exceptionally euryhaline estuarine species. Salinity appears as the main factor in controlling faunal assemblages at both extremes of the estuarine gradient (i.e., tidal inlet and head), whereas sediment type delineates between communities in the mesohaline to polyhaline reaches. Axial (i.e., from tidal inlet to tidal head of the estuary) zonation patterns of macroinfauna broadly matched those of mesozooplankton and fishes, supporting the notion of a general structure underlying species distribution patterns in the Gamtoos estuary. 相似文献
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Catherine E. Lovelock Maria Fernanda Adame Vicki Bennion Matthew Hayes Julian O’Mara Ruth Reef Nadia S. Santini 《Estuaries and Coasts》2014,37(3):763-771
Mangrove forests and saltmarshes are important habitats for carbon (C) sequestration in the coastal zone but variation in rates of C sequestration and the factors controlling sequestration are poorly understood. We assessed C sequestration in Moreton Bay, South East Queensland in mangrove forests and tidal marshes that span a range of environmental settings and plant communities, including mangrove forests and tidal marshes on the oligotrophic sand islands of the eastern side of Moreton Bay and on the nutrient enriched, western side of the bay adjacent to the city of Brisbane. We found that rates of C sequestration in sediments were similar among mangrove forests over the bay, despite large differences in the C density of sediments, because of different rates of vertical accretion of sediments. The C sequestration on the oligotrophic sand island tidal marshes, dominated by Juncus kraussii, had the highest rate of C sequestration in the bay while the western saltmarshes, which were dominated by Sarcocornia quinqueflora, had the lowest rate of C sequestration. Our data indicate C sequestration varies among different tidal wetland plant community types, due to variation in sediment characteristics and rates of sediment accretion over time. 相似文献
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海南岛红树林泥炭形成于热带泥炭聚积区,成炭质料为适盐性的红树林植物群落,堆积环境为泥炭坪,与陆相沼泽泥炭相比,这些特殊性必然反映到泥炭的有机组成上。红树林泥炭有机成份的研究将为合理开发利用海南的泥炭资源提供依据。红树林泥炭有机组成特征及其在泥炭化过程中的变化也必然为探讨泥炭化机理提供大量地质信息。一、海南岛红树林泥炭的一般特征海南岛红树林泥炭以埋藏泥炭为主,主要分布于海南岛东北部沿海地区,以琼山县东寨港和琼海县福田地区发育最好,其成炭环境为泥炭坪。现在正在发育的泥炭坪仅见于文 相似文献
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Mitsugu Nishimura 《Geochimica et cosmochimica acta》1978,42(4):349-357
Detailed geochemical analyses of the high reduction zone in Lake Suwa sediments suggested that the stenol to stanol conversion rate in this zone is primarily controlled by the proportion of autochthonous contribution to organic matter and the redox potential in these sediments, and that land-derived stenols were kept insensitive to hydrogenation in lacustrine sediments as compared with those derived from plankton. These results indicate that stanols derived directly from organisms on land may contribute significantly to stanols found in lacustrine sediments which contain minor proportions of autochthonous organic materials.In order to express the relative autochthonous vs terrigenous contribution to organic matter in lacustrine sediments, the autochthonous contribution index (ACI) was defined based on the characteristic distribution of sterol in plankton and land plants. It systematically increased from river inlet towards lake center and correlated closely with the δ13C value in same sediments. This strongly indicates that ACI is a useful indicator providing informatiom on autochthonous vs terrigenous contribution to the organic material in lacustrine sediments. 相似文献
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Mudflats and associated mangroves are most important ecosystems of tropical coastal regions. Mangroves play a very important role in maintaining the environmental balance; thus in addition to mangrove reforestation and restoration, afforestation has also been practiced. We studied distribution of sediment components (sand, silt, clay) organic carbon (OC), heavy metals (Fe, Mn, Cu, Zn, Cr and Co) and pH in six cores collected from one of the largest mudflats of Mandovi estuary, west coast of India. The temporal distribution patterns of these proxies suggested that past changes in tidal energy conditions, fresh water inflow and anthropogenic activities over the last few decades, together helped in development of a middle tidal flat in this estuary. In cores collected from the mangroves, trapping and deposition of finer particles and organic matter were enhanced by a complex aerial mangrove root system in recent years. Mangroves were, therefore, suggested to enhance the buildup of mudflats in Mandovi estuary. Cores collected from mudflats also exhibited higher deposition of finer particles and organic matter (except MF2) in recent years, suggesting maturity and greater stability of the entire mudflat in recent years. Middle tidal flats (mudflats) of Mandovi estuary may, therefore, prove to be suitable substrates for mangrove proliferation in the near future. Finer sediments deposited mainly from mining activities in recent years exhibited lower pH and higher metal content. Organisms dwelling in these recently deposited sediments are, therefore, at higher risk of bioaccumulation and metal toxicity. 相似文献
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Texture and geochemistry of the sediments of a tropical mangrove ecosystem,southwest coast of India 总被引：2，自引：0，他引：2
The textural and geochemical aspects of the sediments of a tropical mangrove ecosystem have been studied and discussed. The sediments are characterized by the abundance of silt and sand with minor amounts of clay. The mean size of the sediment ranges from 0.205 mm to 0.098 mm (fine to very fine grained sand). The sediments are very poorly sorted, negatively to very negatively skewed, and platy to extremely leptokurtic in nature. The organic carbon content of the sediments ranges from 0,33% to 4.93%, which is controlled by the particle size of the sediments. The CaCO3 content is five times the enrichment of organic carbon. This enhanced CaCO3 content of the mangrove sediments might be a result of the abundance of shell fragments in the sediments. The shell mining activities in the estuarine bed adjoining the Kumarakam mangroves also contribute a substantial amount of lime muds to the mangrove area, which in turn add CaCO3 to the sediments. The relative concentrations of heavy metals are Fe > Mn > Cr > Zn > Ni > Cu. All heavy metals other than Fe show an increase in concentration compared to the other parts of the estuarine bed. Cluster analysis indicates that the contents of organic C, Fe and Mn have a marked bearing on the Cr, Zn, Ni, and Cu levels of the mangrove sediments. 相似文献
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Hashem A. Madkour Abbas M. Mansour Abu El-Hagag N. Ahmed A. El-Taher 《Arabian Journal of Geosciences》2014,7(9):3427-3440
The textural and geochemical aspects of the sediments of subtropical mangrove ecosystem and surrounding areas have been studied and discussed. Forty sediment samples were collected from different areas of mangrove environment and surrounding areas along the Egyptian Red Sea coast. The sediments of each study areas are characterized by the abundance of sand with minor amounts of mud and gravel. The mean size of the sediments ranged from medium grained to fine grained at the study areas. Cluster analysis showed that the distribution of gravel, sand, and mud fractions is related to bottom facies and type of sediment source. Generally, sand fraction is the main category among the three constituents. Carbonate content recorded minor values in the study areas. The CaCo3 content of the sediments ranged from 4.7 % at Hamata area to 64.9 % at Erier area. Terrigenous and biogenic components are the factor controlling of the carbonate content of studies sediments. The organic carbon content ranged from 1.10 at Hamata area to 3.1 % at Sharm el-Qibli and Erier areas, which is controlled by particle size of the sediments. Phosphorus content in the different studied localities is related to the sources of phosphorus to the area. Our observations provide evidence that there are no significant differences in environmental texture and geochemistry of the sediments of subtropical mangrove ecosystem and surrounding areas of the Egyptian Red Sea coast. 相似文献
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滨海红树林泥炭沉积物中硫的赋存特点及其控制因素 总被引：4，自引：0，他引：4
海南和厦门两地滨海红树林沉积物和埋藏泥炭中硫的成分分析表明,滨海红树林沉积物和泥炭中的硫以硫化铁硫为主,有机硫次之,硫酸盐硫含量最低。泥炭沉积物中硫的赋存形式和特点与沉积环境密切相关。海南福田地区红树林泥炭沉积物主要形成于红树林潮上坪和泥炭坪,硫含量较高,平均为2.60%,且有机硫含量与有机碳含量呈正相关,而硫化铁硫含量与有机碳含量没有明显的相关性;厦门海沧镇红树林泥炭沉积物形成于红树林潮间坪以及潮道环境,硫含量较低,平均值仅为0.43%,形态硫和有机质的相关性与海南红树林泥炭地沉积物相反。红树林泥炭沉积物中铁的硫化物主要以黄铁矿形式产出,且以莓球状形态为主。研究表明,黄铁矿与次生有机硫的生成与微生物活动密切相关,造成红树林泥炭中硫含量差异最主要的原因不是硫源,而是有机质的供给与沉积微环境的影响。现代滨海红树林泥炭沼泽中硫的赋存特征将对煤中硫成因的研究提供重要的科学依据。 相似文献
11.
利用在长江口崇明岛北支北四滧港（SY）、北堡港（BBG）以及新卫村（XW）潮滩获取的表层沉积物,测试总有机碳（TOC）、总氮（TN）及总硫（TS）含量,分析有机地球化学元素在潮滩微相的分布规律及影响因素,试图建立TOC/TN、TS/TOC等潮滩微相识别指标。研究结果显示,影响长江口潮滩TN、TS微相分布的重要因素为有机质含量及类型。在淤涨型潮滩,TOC/TN在高潮滩一般大于10,在中潮滩明显降至10以下;中潮滩植被带TS/TOC最高,平均值达0.063,其次为高潮滩互花米草带和中潮滩光滩（分别为0.055和0.054）,高潮滩芦苇带最低;TS-TOC一元线性回归斜率在高潮滩芦苇带呈现为显著低值,自高潮滩米草带向光滩,逐渐增大。在侵蚀型潮滩,TOC/TN从高潮滩到低潮滩均大于10,而且中、低潮滩的比值大于高潮滩,潮下带骤降至小于10;TS/TOC自陆向海逐渐增大,TS-TOC一元回归斜率高潮滩最低,中潮滩最高。另外,侵蚀型潮滩各微相的TS-TOC一元线性回归斜率均明显低于淤涨型潮滩。上述研究结果表明,长江口沉积物的TOC/TN和TS/TOC及TS-TOC一元线性回归斜率与潮滩沉积微相之间存在一定的关系,具有应用于全新世钻孔识别潮滩沉积物微相的潜力。 相似文献
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Christine L. Weilhoefer Walter G. Nelson Patrick Clinton David M. Beugli 《Estuaries and Coasts》2013,36(2):377-389
We investigated whether within wetland environmental conditions or surrounding land cover measured at multiple scales were more influential in structuring regional vegetation patterns in estuarine tidal wetlands in the Pacific Northwest, USA. Surrounding land cover was characterized at the 100, 250, and 1,000 m, and watershed buffer scales. Vegetation communities were characterized by high species richness, lack of monotypic zonation, and paucity of invasive species. The number of species per site ranged between 4 and 20 (mean?±?standard deviation?=?10.2?±?3.1). Sites supported a high richness (mean richness of native species 8.7?±?2.8) and abundance of native macrophytes (mean relative abundance 85 %?±?19 %). Vegetation assemblages were dominated by a mix of grasses, sedges, and herbs with Sarcocornia pacifica and Distichlis spicata being common at sites in the oceanic zone of the estuary and Carex lyngbyei and Agrostis stolonifera being common at the fresher sites throughout the study area. The vegetation community was most strongly correlated with salinity and land cover within close proximity to the study site and less so with land cover variables at the watershed scale. Total species richness and richness of native species were negatively correlated with the amount of wetland in the buffer at all scales, while abundance of invasive species was significantly correlated to within wetland factors, including salinity and dissolved phosphorus concentrations. Landscape factors related to anthropogenic disturbances were only important at the 100-m buffer scale, with anthropogenic disturbances further from the wetland not being influential in shaping the vegetation assemblage. Our research suggests that the traditional paradigms of tidal wetland vegetation structure and environmental determinants developed in east coast US tidal wetlands might not hold true for Pacific Northwest wetlands due to their unique chemical and physical factors, necessitating further detailed study of these systems. 相似文献
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A comparative study of lignin and neutral carbohydrate compositions, combined with C, N and δ13C analyses, was carried out on sedimentary cores, and on various vascular plant species collected in mangrove swamps of French Guiana. The main purpose of this study was to assess the diagenesis of carbohydrates and lignin in brackish to hypersaline fine-grained mangrove sediments characterized by great changes in redox conditions. Distribution of carbohydrates in sediments reflects both the lability of these compounds and their efficient recycling. They are subject to selective degradation, cellulosic glucose and xylose appearing to be the two most labile neutral sugars. In contrast a relative increase in arabinose, rhamnose, fucose and hemicellulosic glucose between plants and sediments, suggests that they may be more refractory and/or that they also derive from microbial synthesis. The total carbon from lignin-derived phenols is higher in sediments than in mangrove plants as a consequence of their rather refractory character. Nevertheless, evidence of lignin decomposition was found to be independent of local environmental conditions. The various redox processes that occur in mangrove sediments depend on plant species, stages in forest development and season. Different redox conditions induce different mechanisms for the decomposition of lignin and thus induce changes in phenol distributions. At depth, in most mangroves, an increase in (Ad/Al)v ratios and in deoxy sugars (fucose and rhamnose) content was significantly correlated with increased proportions of oxidized allochthonous organic debris deriving from the Amazonian detrital discharge, thus suggesting a specific source effect rather than a diagenesis induced change. Therefore, this study illustrates that both lignin and cellulose, derived from vascular plant debris, can be degraded in waterlogged mangrove sediments, and that their distribution depends on environmental conditions. 相似文献
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Andrea C. Alfaro 《Estuaries and Coasts》2006,29(5):731-736
The zonation of mobile species, such as grazing snails, may be influenced by migration patterns, which often are missed if
the population is not sampled within the appropriate temporal scales (i.e., tidal cycles, diurnal periods, seasons). Aspects
of community ecology, especially abundance, biodiversity, and habitat preferences, are better described when the mobility
of different species or group of organisms also are investigated. The effect of migration on the density and size-frequency
distribution of a dominant intertidal grazer (Turbo smaragdus) was investigated across four habitats (mangrove tree, pneumatophore, algal aggregation, and seagrass bed) during emersion
and immersion periods at Matapouri Estuary, northern New Zealand, in August 2004 and March 2005. Snails were marked and recaptured
to identify their specific movements across the four zones during high and low tide periods. Results from the population surveys
and the marked-recaptured experiments indicate that snails migrate upward during high tide and do wnward during low tide.
These snail movements appear to be related to improved feeding activity during tidal inundation within macroalgal aggregations
in the pneumatophore and algal zones. Large snails (up to 48 mm in width) were predominant in the highest zone among the mangrove
trees, where they appear to feed on filamentous algae and microalgae that cover the sediment and plant surfaces in this area.
Differences in snail density and sizes between the two sampling months were attributed to reproductive patterns of this species,
which result in about 30% more snails (mostly juveniles) during peak reproduction in March. 相似文献
15.
Grain size and geochemical analyses have been carried out on 58 samples collected from different areas of mangrove environment
of the Egyptian Red Sea coast. The texture characteristics of mangrove sediments show that the mean size decreases in sediments
of coastal areas while increase in island sediments and the sediment type generally changes from sand to slightly gravelly
muddy sand. The sediments are composed mainly of poorly sorted, negatively nearly symmetrical and leptokurtic fine sands.
Cluster analysis showed that, distribution of gravel, sand and mud fractions is related to bottom facies and type of sediment
source. Generally, sand fraction is the main category among the three constituents. Geochemically the factor controlling the
carbonate content of studied sediments includes material supply of biogenic and terrigenous components. Therefore, sediments
of Hamata area, km 17 south Safaga, Wadi El-Gemal Island and Abu-Minqar Island are terrigenous sediments, while sediments
of km 37 north Quseir are highly carbonates. In general organic matter is higher in the mangrove sediments relative to adjacent
areas. The high organic matter in the mangrove sediments is primarily due to the high supply from primary productivity, terrestrial
and reworked sediments. Texture is the main controlling factor for the organic matter enrichment. Spatial variations in the
phosphorus content in the different studied localities are related to the sources of phosphorus to the area. In comparison,
cluster analysis indicates that phosphorus might be transported from terrestrial source to the sea through wadis draining
the excavated Upper Cretaceous phosphate rocks. Also, the abundance of phosphorus content may be attributed to phosphatization
of calcareous skeletons. Our observations provide knowledge on the physico-chemical effects and will be useful in the management
and suitable development of the areas under study. In addition it represent database in the future. 相似文献
16.
Crabs (Grapsidae,Sesarma) are the dominant macrofaunal group of mangrove forest soils in northern Australia. Little is known about the ecology of these crabs or the factors that influence their distribution in mangrove forests. Pitfall traps were used to sample grapsid crabs in the Murray River estuary in north Queensland. Sampling was conducted at five sites along a salinity gradient from <1‰ at upstream sites to >35‰ at the river mouth. At each site, trapping was done in both low and high intertidal forests. We characterized the sediments at each site by measuring percent sand, silt, clay and organic matter, Eh, pH, and soil pore-water salinity. Four species of grapsids dominated the crab fauna along the Murray River (Sesarma semperi-longicristatum, S. messa, S. brevicristatum, andS. brevipes). Distinct zonation patterns were found along the salinity gradient and between high and low intertidal forests.S. messa was dominant in high intertidal, downstream forests, high and low intertidal forests in the middle to downstream portion of the river, and in low intertidal forests in the central reach of the river.S. brevipes was dominant in both low and high intertidal zone forests at low salinity upstream sites.S. brevicristatum was most abundant in the central reaches of the river and only in the high intertidal zone.S. semperi-longicristatum was found only in the low intertidal zone, downstream forest. Subsequently, tests of salinity tolerances of these crabs were carried out in the laboratory. These indicated very wide tolerances over salinities from completely fresh to hypersaline (60‰). The osmoregulatory abilities of the crabs were also found to vary. However, neither their salinity tolerance nor osmoregulatory ability adequately explain the zonation patterns were measured in the field. For example,S. brevicristatum had the most restricted distribution, but it had the second broadest salinity tolerance and osmoregulatory ability. Sediment characteristics explained a significant amount of the variation in abundance for two of the crab species. Pore-water salinity provided no explanatory power for any of the species. Individual species abundances are probably influenced by additional factors such as interspecific competition and predation. 相似文献
17.
To determine the role of mangroves for fisheries in the arid region of the Persian Gulf, we investigated fish community structure and trophic diversity in intertidal creeks with and without mangroves. Fish community abundances and biomass were compared across habitats and seasons. To identify variations in overall community trophic niches among habitats and seasons, we measured niches with size-corrected standard ellipse areas (SEAc) calculated from C and N stable isotope values. Although there was a slightly greater species richness occurred in mangrove creeks, we found a general similarity in the diversity patterns in creeks with and without mangroves. Also, there were no consistent differences in fish abundance or biomass for mangrove vs. non-mangrove fish collections. Community trophic diversity measured as SEAc also showed no significant difference between mangrove and non-mangrove sites. Instead, strong seasonal patterns were observed in the fish assemblages. Winter samples had consistently higher fish abundance and biomass than summer samples. Winter SEAc values were significantly higher, indicating that the fish community had a larger isotopic niche in winter than summer. Overall, we found that seasonality was much stronger than habitat in determining fish community structure and trophic diversity in the mangrove and non-mangrove ecosystems of Qeshm Island, Iran. 相似文献
18.
Scott G. Johnston Annabelle F. Keene Richard T. Bush Edward D. Burton Leigh A. Sullivan Lloyd Isaacson Angus E. McElnea Col R. Ahern C. Douglas Smith Bernard Powell 《Chemical Geology》2011,280(3-4):257-270
Tidal inundation is a new technique for remediating coastal acid sulfate soils (CASS). Here, we examine the effects of this technique on the geochemical zonation and cycling of Fe across a tidally inundated CASS toposequence, by investigating toposequence hydrology, in situ porewater geochemistry, solid-phase Fe fractions and Fe mineralogy. Interactions between topography and tides exerted a fundamental hydrological control on the geochemical zonation, redistribution and subsequent mineralogical transformations of Fe within the landscape. Reductive dissolution of Fe(III) minerals, including jarosite (KFe3(SO4)2(OH)6), resulted in elevated concentrations of porewater Fe2+ (> 30 mmol L?1) in former sulfuric horizons in the upper-intertidal zone. Tidal forcing generated oscillating hydraulic gradients, driving upward advection of this Fe2+-enriched porewater along the intertidal slope. Subsequent oxidation of Fe2+ led to substantial accumulation of reactive Fe(III) fractions (up to 8000 μmol g?1) in redox-interfacial, tidal zone sediments. These Fe(III)-precipitates were poorly crystalline and displayed a distinct mineralisation sequence related to tidal zonation. Schwertmannite (Fe8O8(OH)6SO4) was the dominant Fe mineral phase in the upper-intertidal zone at mainly low pH (3–4). This was followed by increasing lepidocrocite (γ-FeOOH) and goethite (α-FeOOH) at circumneutral pH within lower-intertidal and subtidal zones. Relationships were evident between Fe fractions and topography. There was increasing precipitation of Fe-sulfide minerals and non-sulfidic solid-phase Fe(II) in the lower intertidal and subtidal zones. Precipitation of Fe-sulfide minerals was spatially co-incident with decreases in porewater Fe2+. A conceptual model is presented to explain the observed landscape-scale patterns of Fe mineralisation and hydro-geochemical zonation. This study provides valuable insights into the hydro-geochemical processes caused by saline tidal inundation of low lying CASS landscapes, regardless of whether inundation is an intentional strategy or due to sea-level rise. 相似文献
19.
Coastal-marine sedimentation conditions in the Pechora River delta, Korovinskaya Bay, and intertidal zone of the Pechora Sea are characterized by diverse physicochemical processes that define the differentiation of mineral and organic components of sediments. On the basis of a complex study of abundant observation data, lithostructural and geochemical (including organic-geochemical) features of sediments in different facies circumstances of a common lateral series are considered. Synchronous changes in mineral and organic components are also taken into account. Informative numerical indices characterizing sediments of different facies conditions and lithodynamic–geochemical regimes of their formation are defined. Major factors of sedimentation and early diagenesis are distinguished. Each facies type of sediments is considered a product of sedimentary-diagenetic differentiation of polycomponent substance in certain hydrodynamic and geochemical conditions. These processes are dramatically manifested under deltaic coastal-marine complex conditions that serves as a natural lithodynamic and geochemical barrier. 相似文献
20.
Aleksandra AJNOV Vladimir SIMI Branimir JOVANIEVI Olga CVETKOVI Radovan DIMITRIJEVI Nenad GRUBIN 《《地质学报》英文版》2008,82(6)
Sediments of the western part of the Valjevo-Mionica basin (Serbia) were examined both geochemically and mineralogically to explain, on the basis of their sedimentological characteristics, the causes of changes in their qualitative and quantitative composition. A total of 62 samples obtained from the drillhole at depths up to 400 m was investigated. Using correlation of the obtained data, six geochemical zones were defined, two of which being specially distinguished by their mineralogical, geochemical and sedimentological characteristics. The first one, upper zone A, consists of banded marlstones interbedded with clay and oil shales and is characterized by presence of analcite and searlesite. These minerals and very high contents of Na2O indicate sedimentation in alkaline conditions with increased salinity in arid climate. That provided pronounced water stratification, as well as higher bioproductivity in the basin and sedimentary organic matter preservation. Therefore, the zone A sediments are characterized by high organic matter contents of the type which provides good potential for production of liquid hydrocarbons. Another specific zone, zone F, contains sediments with very high MgO, K2O and Li concentrations. Their geochemical correlation, as well as almost complete absence of illite in this zone, indicates the presence of interstratified clay mineral type illite-saponite (lithium-bearing Mg-smectite). 相似文献