A preliminary analysis of the formation of travertine and travertine cones in the Jifei hot spring,Yunnan, China

The Jifei hot spring emerges in the form of a spring group in the Tibet–Yunnan geothermal zone, southwest of Yunnan Province, China. The temperatures of spring waters range from 35 to 81°C and are mainly of HCO₃–Na·Ca type. The total discharge of the hot spring is about 10 L/s. The spring is characterized by its huge travertine terrace with an area of about 4,000 m² and as many as 18 travertine cones of different sizes. The tallest travertine cone is as high as 7.1 m. The travertine formation and evolution can be divided into three periods: travertine terrace deposition period, travertine cone formation period and death period. The hydrochemical characteristics of the Jifei hot spring was analyzed and compared with a local non-travertine hot spring and six other famous travertine springs. The results indicate that the necessary hydrochemical conditions of travertine and travertine cones deposition in the Jifei area are (1) high concentration of HCO₃ ⁻ and CO₂; (2) about 52.9% deep source CO₂ with significantly high value; (3) very high milliequivalent percentage of HCO₃ ⁻ (97.4%) with not very high milliequivalent percentage of Ca²⁺ (24.4%); and (4) a large saturation index of calcite and aragonite of the hot water.     

Tidal and seasonal variations of sulfate ion in a New Jersey marsh system

Sulfate variations during a tidal cycle were investigated at three sites in a highly polluted tidal marsh. Sulfate- chlorinity relationships were determined in the light of fluctuations in temperature, dissolved oxygen and pH. The relationships were found to be seasonal in nature, being affected by temperature and rainfall effects on biologic productivity. Both reduction of sulfate ion to a sulfide species and oxidation of sulfide species to the sulfate ion were found to occur. Consideration of the sulfide oxidation process suggests the possibility that metals precipitated as sulfides may be mobilized and redistributed in the marsh system.     

Global travertine deposition modulated by oscillations in climate

Travertine deposits are important records of past fluid flow in the Earth's crust, and document fluid migration through both tectonic activity and changes in climate. While many studies hint at possible relationships between travertine formation and global climate, none have investigated these connections on a global scale. Here we compile 1649 published travertine ages from six continents to test the hypothesis that global and/or regional changes in climate regulate travertine deposition. Peaks in bedded travertine ages occur with main frequencies that correspond to 100‐kyr changes in global climate, where most peaks occur during glacial terminations or interglacial periods, including a large peak that coincides with the Early Holocene climatic optimum. Time–series analysis also suggests a possible connection with 41‐kyr obliquity cycles. At regional scales, many peaks also correspond with local times of high precipitation or wet conditions. This can be attributed to higher groundwater recharge rates, providing the necessary water to form travertine. Many bedded travertine‐depositing systems may therefore be water‐limiting and sufficient CO₂ may be present even during times of no travertine deposition. Exceptions to this conclusion are banded vein travertine deposits, which typically form during times of dry climate when water tables are low. Copyright © 2019 John Wiley & Sons, Ltd.     

雪宝顶流域钙华景观生态风险评价的研究探讨

景观生态风险评价能够有效地对区域景观格局进行优化并为风险防范提供理论基础。文献计量学分析表明,国内岩溶景观生态风险评价研究主要从“研究对象”、“评价模型”、“评价方法”和“评价指标”4个方面分析;而钙华作为特殊的岩溶体,目前对它的生态风险评价几乎未开展。文章从岩溶景观生态风险评价入手,基于模糊数学综合评判法和层次分析法,提出以地表钙华体与地表水循环作为景观主体,并对主体因素逐步细化,形成多层次综合评价模型,展开对雪宝顶流域钙华景观的生态风险评价。     

钙华非经典沉积的纳米生长过程与调控机制初探——以九寨沟—黄龙钙华形成为例

钙华是自然界重要的岩溶碳酸盐沉淀之一,其形成过程往往受到生命活动的影响,弄清钙华生物沉积作用有助于更好地理解钙华微岩相结构和地球化学特征的气候环境指示意义。本文以黄龙-九寨沟钙华形成为例,阐述黄龙-九寨沟现代钙华纳米结晶特征、纳米钙华的生长和集合体形态,分析模拟实验中生物有机质对钙华生长和形貌的调控原因,揭示了生物活动和代谢产物对纳米钙华成核、生长及钙华晶体形貌的调控两途径四阶段机制;为探究钙华成因、碳酸钙生长调控机制、钙华退化的因素及其保护和可持续利用钙华景观具有重要的科学价值。      

雪宝顶区块流域钙华形成的生物作用研究

钙华不仅具有重要的景观旅游价值,而且对确定区内碳酸盐沉积特征、环境演化规律及同期环境生物的作用与贡献有重要的研究意义。本文在对比国内外典型钙华特征的基础上,以黄龙和九寨沟为例,对雪宝顶区块流域内钙华的沉积特征、环境化学与生物作用进行阐述,指出了雪宝顶区块流域冷水型钙华的形成与演化是化学沉积-溶解作用、生物沉积与溶蚀作用等共同作用的结果,并受非生物、生物因素影响。在雪宝顶冷水型钙华的形成过程中,微生物协同参与了钙华的沉积与溶蚀过程,通过自身新陈代谢促活动促使使钙离子结晶,并诱导晶型变化;其他生物体如植物、藻类等或以间接的方式促进或加快了钙华形成,或为钙华生长提供模板和体量。     

钙华体次生有机体系的界面结晶作用研究

本文总结了钙华体次生有机体系中生物群落特征和界面结晶行为,根据生物在碳酸盐沉积中的角色,将钙华体中次生有机体系的界面结晶矿化类型分为生物控制矿化沉积和生物诱导矿化沉积。分述了碳酸钙沉积矿化相关的五种生物代谢活动,讨论了生物胞外聚合物（EPS）对碳酸钙矿物晶型和形貌的影响。针对目前钙华研究中存在的问题,今后应深入研究生物体主要构成元素、生物小分子和生物体内部组织在钙华形成或退化中的作用,进一步厘清钙华体与次生有机体系的多界面溶化方式,为钙华保护修复及钙华退化治理措施提供科学依据。      

Geochemical mechanisms of travertine formation from fresh waters in southern Siberia

The subject of study was the chemical composition of common fresh-water springs precipitating travertines in tectonically passive regions of the Kolyvan'-Tomsk folded area and northwestern Salair. Attention was paid to the specific character of manifestation, mineralogy, and petrography of the produced travertines. Results of the study of isotopic composition of carbon in hydrocarbonate ion of waters and carbonate travertines are reported. It is shown that the genetic type of CO₂ accompanying the formation of travertines is biogenic. Study of the equilibrium of the underground waters with aluminosilicate and carbonate minerals has shown that the travertines are the product of evolution of an equilibrium-nonequilibrium water-rock system. New mechanisms of travertine formation from cool fresh waters are proposed.     

Long-term analog of carbonation in travertine from Uleimat Quarries, Central Jordan

Quaternary travertine capping the metamorphic (cement) zones in Uleimat Quarries, central Jordan, has been precipitated from hyperalkaline paleogroundwaters. Such waters are similar to the cement pore water and to the present day hyperalkaline seepages (pH 12.5) in Maqarin, north Jordan. The isotopic depletions observed in Uleimat travertine, with δ¹³C values as low as −25.45‰, suggest that they have been precipitated during CO₂ uptake by highly alkaline calcium hydroxide waters. The travertine in Uleimat Quarries indicates a long-term analog of carbonation and remobilization of silica in cementitious barriers for radioactive waste repositories. The presence of Cr-rich smectites and relatively high levels of Cr (4.1%), V (657 ppm), Ni (163 ppm), Zn (634 ppm) and U (34 ppm) in the green travertine and the associated opaline silica phases suggests the use of the Uleimat travertines as analogs with the repository disturbed zone. Smectites and silica phases are expected to be a sink for alteration products in the late stage evolution of a high pH plume. Co-precipitation of these elements in mineral phases is of great importance to control the concentration of these elements in groundwater.     

The quaternary travertine deposits of Europe and Asia Minor

A summary is provided of the published information relating to all aspects of Quaternary travertine formation in Europe west of the Ural Mountains. The deposits have been divided into two broad groups, the meteogene travertines, which result primarily from the degassing of soil-borne aqueous CO₂, and thermogene deposits resulting from the degassing of thermally generated CO₂. Meteogene deposits are rare above latitude 58°N, and in regions where the mean annual air temperature is below 5°C. A significant positive correlation exists between mean air temperature and travertine deposit thickness. The combined effects of temperature and rainfall are used to provide a zoned map showing the travertine-forming potential of limestones within the region. Information from ¹⁴C dating indicates that deposition reached a maximum in the period 5–10 ka BP) and is currently limited by land and water management practices in the populated areas. Thermogene deposits occur in regions of high CO₂ discharge resulting from tectonic activity, such as Italy and Turkey where there is much vulcanism. These travertines are frequently more massive and less readily weathered than meteogene deposits. Fully referenced information is provided for 320 important, mostly well studied sites (227 meteogene, 93 thermogene), of which 156 are currently active.     

钙华天然海绵地质体多孔特性及其对水循环调节意义——以四川黄龙为例

四川黄龙自然遗产点以钙华景观闻名海内外,其钙华体多孔性地质结构,使钙华地质体具备"海绵"特性。本文通过电子扫描显微镜(SEM)和探地雷达、电磁法等地质探测技术对钙华地质体的多孔性质和水循环特性进行研究,并结合多年现场踏勘经验探讨了钙华地质体的多孔性质对水循环的调节意义。分析结果显示,黄龙钙华体经过地质作用形成了不同尺度的孔隙结构,其中生物参与形成的微观孔道具备"渗透、净化"功能;侵蚀作用产生的可视孔洞、缝隙快速透水,并进一步发育成塌陷区和钙华漏斗。彩池、溶洞和裂缝为水体储蓄和运移提供很好通道和场所,地质探测分析表明典型钙华段地下腔体具备"蓄水、排水"功能。各尺度孔隙互相影响,共同调节黄龙景区内的地表-地下水循环系统。初步研究发现,藻类在黄龙钙华沉积过程中具有加速和减少孔隙形成的双向调控作用,未来将结合藻类在钙华构筑过程的作用,继续深化黄龙钙华地质体的孔隙结构性质研究,为钙华景观的维护和保育提供参考。     

九寨沟黄龙地区钙华漏斗的特征与成因探讨

九寨沟黄龙地区广泛发育着钙华滩流、湖泊、瀑布、洞穴与漏斗。本文对钙华漏斗进行了特征描述和成因分析,并将其与钙华池、盆特征进行了对比,进而得出钙华漏斗导致九寨沟地区景观水量减少的结论,并提出解决这一重要问题的办法是工程堵漏。本文对九寨沟黄龙地区景观的开发利用和环境保护具有重要的参考价值。     

A new technique for precise uranium-series dating of travertine micro-samples

Secondary carbonate formations, such as travertine and calcareous tufa deposits, are important archives for quaternary continental climate studies and archaeology. The extremely complex growth mechanisms result in some serious problems for precise mass spectrometric uranium-series dating. Often, detrital and organic particles contaminate the carbonate and large pore volumes yield a great potential for open system behavior. We utilized microscopic, mineralogical and geochemical methods prior to sample selection to determine the abundance of primary calcite, i.e. micrite and spar. Furthermore, the state of alteration was characterized by cathodoluminescence and trace-element analysis. We conclude that travertine and calcareous tufa are appropriate for precise U-series age determination if a) micrite and/or spar are the dominant phases; b) cathodoluminescence of both phases is weak or absent; c) Fe and Al levels are low; and d) Sr concentrations are close to the average of the studied site. We mapped and sampled solely areas of major micrite/spar abundance having minor alteration for accurate U-series dating. When this new method was applied, travertines located in eastern Germany (sites Bad Langensalza, Burgtonna and Weimar-Ehringsdorf) gave single ²³⁰Th/²³⁸U-ages consistent with the lithological growth sequence and greatly improved compared to previously published chronologies. In addition, we determined ²³⁰Th/U isochron ages on bulk samples that confirm our single ages. In contrast to primary calcite, pore cements are homogeneously distributed throughout the travertine fabric and reflect early diagenetic processes and/or weathering.     

The geochemistry of salt marshes: Sedimentary ion diffusion,sulfate reduction,and pyritization

A series of seasonal cores was taken in a high marsh near the terminus of Delaware Bay, U.S.A. A seasonal harmonic diffusion model was successfully fit to the concentration profiles of chloride ion in the salt marsh pore waters yielding a calculated sedimentary diffusion coefficient.Virtually all other chemical reactions within salt marsh sediments are directly linked to the rate and stoichiometry of organic decomposition. The rich organic input from the grass Spartina alterniflora is oxidized anaerobically through the process of sulfate reduction. Over 90% of this net decomposition of organic matter takes place in the uppermost 20 cm. The model for sulfate reduction proposed yields an internally consistent set of both pore water (HCO^?₃, NH⁺₄, HPO^2?₄, HS^?, SO^2?₄) and solid phase (FeS₂) distribution profiles for these sediments. Steady state assumptions and the use of mean annual constants can be employed to model the net rates of diagenetic processes in salt marshes. The pore water concentrations of sulfate ion as well as those ions released by sulfate reduction (HCO^?₃, NH⁺₄, HPO^2?₄, HS^?) are modeled by a system composed of an upper zone, where extensive reconsumption of these metabolite ions occurs, and a lower zone where steady state production and no ion reconsumption occurs.A major product of the sulfate reduction is pyrite, whose accumulation rate is greatest between 7 and 9 cm depth, where it equals the net rate of sulfate reduction. Above this zone little pyrite accumulates due to extensive reoxidation. Below 9 cm the rate of pyritization is controlled by the rate of sulfidation of a refractory iron phase.     

Geotechnical handicap of travertine with different lithotype levels as foundation material

Two major earthquakes occurred on October 23rd, 2011 (M=7.1) and November 9th, 2011 (M=5.6) in Tabanli and Edremit districts of Van province in Turkey, respectively. New settlement areas for Van city were determined after these destructive earthquakes. One of the most important areas for new settlements to be built was Edremit region, consisting travertine where nearly 80% of new housing units (12.384) were built by TOKI (Housing Development Administration of Turkey). Travertines have different lithotypes depending on their depositional process such as crystalline crust, shrub, reed which can affect mechanical and engineering properties of travertine and each level has different handicaps. The purpose of this study is to investigate the relationship between lithotype and physico-mechanical properties of travertines. According to the results, lithotype has an effect on physical, mechanical and rock mass properties of travertine. It is ascertained by several research methods that various handicaps may occur on such areas when the active tectonic structure of the area is evaluated along with the karstic cavities within the travertine and different lithotype qualities.     

Characterization of solid bitumens originating from thermal chemical alteration and thermochemical sulfate reduction

Solid bitumen can arise from several reservoir processes acting on migrated petroleum. Insoluble solid organic residues can form by oxidative processes associated with thermochemical sulfate reduction (TSR) as well as by thermal chemical alteration (TCA) of petroleum. TCA may follow non-thermal processes, such as biodegradation and asphaltene precipitation, that produce viscous fluids enriched in polar compounds that are then altered into solid bitumens. It is difficult to distinguish solid bitumen formed by TCA from TSR since both processes occur under relatively high temperatures. The focus of the present work is to characterize solid bitumen samples associated with TSR- or TCA-processes using a combination of solid-state X-ray Photoelectron Spectroscopy (XPS), Sulfur X-ray Absorption Near Edge Structure Spectroscopy (S-XANES), and ¹³C NMR. Naturally occurring solid bitumens from three locations, Nisku Formation, Brazeau River area (TSR-related); La Barge Field, Madison Formation (TSR-related); and, the Alaskan North Slope, Brooks Range (TCA-related), are compared to solid bitumens generated in laboratory simulations of TSR and TCA.The chemical nature of solid bitumens with respect to organic nitrogen and sulfur can be understood in terms of (1) the nature of hydrocarbon precursor molecules, (2) the mode of sulfur incorporation, and (3) their concentration during thermal stress. TSR-solid bitumen is highly aromatic, sulfur-rich, and nitrogen-poor. These heteroatom distributions are attributed to the ability of TSR to incorporate copious amounts of inorganic sulfur (S/C atomic ratio >0.035) into aromatic structures and to initial low levels of nitrogen in the unaltered petroleum. In contrast, TCA-solid bitumen is derived from polar materials that are initially rich in sulfur and nitrogen. Aromaticity and nitrogen increase as thermal stress cleaves aliphatic moieties and condensation reactions take place. TCA-bitumens from the Brooks Range have <75% aromatic carbon. TCA-bitumens exposed to greater thermal stress can have a higher aromaticity, like that observed in TSR-bitumens. Organic sulfur in TCA-organic solids remains relatively constant with increasing maturation (S/C atomic ratio <0.035) due to offsetting preservation and H₂S elimination reactions. Although S-XANES and ¹³C NMR provide information needed to understand changes in structure and reactivity that occur in the formation of petroleum solids, in some cases XPS analysis is sufficient to determine whether a solid bitumen is formed by TCA or TSR.     

万年尺度下钙华的古环境重建检验——以青海冰凌山为例

采用钙华中微量元素进行古气候环境重建为近年来国内外研究热点。前人研究成果主要为小时间尺度古气候环境重建,因微量元素的影响机制及地区间差异性问题,可能存在未知因素影响稀土元素含量及Mg/Ca、Mg/Sr比值,从而导致解译的古气候环境意义失真。以位于青海省格尔木地区的达布逊湖达1井孢粉谱图与青藏高原湖区变化谱图为参照对象,对青海省平安县三合镇东北冰凌山万年尺度下钙华的古环境重建方法进行了检验,结果表明：1）冰凌山泉华台地沉积环境相对稳定,提供冰凌山钙华物质来源的地下水长期处于接受来自地壳深部CO₂补给的偏酸性条件下;2）所采集钙华样品除P04点外,均具有相同的物质来源和形成过程;3）万年尺度下,用钙华中的稀有元素总量重建古气温方法可行,且稀有元素总量与古气温呈负相关关系;4）采用Mg/Ca、Mg/Sr比值重建古降水环境应区分钙华成因类型,表生钙华Mg/Ca、Mg/Sr比值与古降水呈现负相关,而内生钙华Mg/Ca、Mg/Sr比值与古降水呈现正相关

     

Aragonite laminae in hot water travertine crusts, Rapolano Terme, Italy

Small (5–30 μm) aggregates of aragonite needles occur in calcite crystal crusts of present day hot water slope travertines at Rapolano Terme in Tuscany, Italy. The aggregates are mainly concentrated in irregular, wispy and dark laminae which cross-cut calcite crystal feathers to create a pervasive millimetre scale banded appearance in the deposit; they also occur less commonly scattered irregularly through the calcite layers. The aragonite needle aggregates are in the form of crosses, fascicles (sheaf shaped bundles, or dumbbell shaped), rosettes and spherulites. Locally, irregular masses of needles also occur. The fascicles, rosettes and spherulites have hollow centres which resemble microbial components (?fungal spores, bacterial colonies and pollen), suggesting that the aragonite crystals are biotically nucleated. The lamination is interpreted to reflect diurnal control. Stimulation of microbial activity during daylight concentrates cells in laminae and promotes aragonite calcification. Calcite feather crystals, although traversed by the aragonite aggregate laminae, have a clear appearance under the light microscope. They form more or less continuously through the diurnal cycle by abiotic precipitation. The constant association of aragonite with organic nuclei, irrespective of whether the latter are in laminae or scattered through the calcite layers, supports a biotic control on aragonite formation. Lamination in Pleistocene travertines is superficially similar to that in the present day deposits, but is diagenetically altered. In the Pleistocene deposits, the calcite feathers appear dark under the light microscope and the aragonite aggregates, where they are not altered to dark calcite, are dissolved, together with parts of the adjacent spar calcite, and therefore appear light coloured.     

黄龙钙华纹层石特征与成因分析

为了探究黄龙钙华纹层石剖面褐-白相间混积纹层的特征与成因,对黄龙钙华样品进行了采集和分析。通过微波消解法分析不同颜色纹层钙华样品有机碳含量,并用X射线衍射仪(XRD)、扫描电子显微镜(SEM)、元素分析仪等对样品的晶相、形貌、元素和Mg/Ca比等进行了分析。结果表明,黄龙钙华褐-白纹层有机碳含量、Mg/Ca比存在明显差异,褐色纹层有机碳含量、Mg/Ca分别高于相邻的白色纹层,有机碳的含量随着沉积顺序(由老到新)逐渐变大。钙华剖面年层中的褐-白相间纹层不仅受到微生物、植物等生物的影响,还受不同温度、水动力等气候因素的调控,即黄龙钙华剖面年层中出现褐-白相间纹层为生物-气候双成因。其结果可为寻找黄龙钙华沉积过程中生物参与证据提供一定的理论基础。     

四川黄龙沟景区钙华的起源和形成机理研究

对四川黄龙沟钙华景区的水化学测试发现，形成黄龙沟钙华的泉水具有很高的Ca^2 和HC03^-离子浓度，相应地，泉水的C02分压显著高于大气和土壤生物成因所能产生的C02分压。结合泉水出露的地质条件和泉口C02气体碳稳定同位素组成(δ^13C＝—6．8‰)的分析，进一步发现，高C02分压与深部成因的C02有关。可见，黄龙沟钙华属于热成因类钙华，而非原来普遍认为的“是气候岩溶作用的产物”。此外，黄龙沟钙华的大量出现与水中方解石的迅速沉积、Ca^2 和HC03^-浓度的大量降低有关。随着地下水自泉口出露，由于水的C02分压远高于大气，水中C02大量释放于大气，结果水的pH值迅速升高，方解石饱和指数由泉口的负值很快转变为高的正值，为方解石的沉积奠定了必要的物理化学基础。放置于水中的大理岩石片观测表明，流速较快的边石坝处的方解石沉积速率是其附近水池内的2—5倍，这清楚地显示了水动力条件对沉积速率的控制。进一步根据DBL理论模型分析发现，水动力条件对方解石沉积速率的控制在于其对固液界面间扩散边界层(DBL)厚度的影响，流速愈快，DBL厚度愈薄。且DBL厚度最终制约着沉积表面的化学组成浓度，即厚度愈小，表面H^ 浓度愈低(或pH愈高)、方解石饱和指数愈高，进而方解石沉积愈快。