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1.
Li Guo  & Robert Riding 《Sedimentology》1999,46(6):1145-1158
Holocene hot water travertine continues to form at Terme San Giovanni, near Rapolano Terme, central Italy, although artificial diversion of the water has reduced deposition. Mesothermal water (≈38–39 °C) emerging from fault-controlled vents located on a hilltop has created a linear fissure ridge 240 m long and up to 10 m high. Active parts of the ridge crest are covered by small cones; inactive parts are locally neotectonically fissured and have small pools. Ridge deposits include crystalline crust, paper-thin raft and shrub lithotypes. The ridge has both smooth and terraced marginal slopes, dominated by crystalline crusts with small shrubs in terrace pools. At the base of the ridge, there is a rapid transition to lateral flats and depressions, where water from the ridge collects and deposits shrub, irregular pisoid, reed, paper-thin raft and fine-grained and organic-rich travertines. Water channelled to nearby valley sides deposits thick crystalline crusts on valley slopes and waterfall overhangs, locally with small pools filled by smooth spherical pisoids. On the valley floor, mixing of waters forms varied stream-fill deposits that include micritic reed, paper-thin raft and coated bubble travertines. The diversity of travertine facies observed results from the location of the Terme San Giovanni hot springs on a hill crest, thus providing a wide array of downslope locations for further deposition. The abrupt facies transitions observed are characteristic of hot spring carbonates and result from a combination of rapid decrease in precipitation away from vents, variations in local surface topography and the feedback effect of travertine deposition itself, which dams and diverts water flow.  相似文献   

2.
Calcite dendrite crystals are important but poorly understood components of calcite travertine that forms around many hot springs. The Lýsuhóll hot-spring deposits, located in western Iceland, are formed primarily of siliceous sinters that were precipitated around numerous springs that are now inactive. Calcite travertine formed around the vent and on the discharge apron of one of the springs at the northern edge of the area. The travertine is formed largely of two types (I and II) of complex calcite dendrite crystals, up to 1 cm high, that grew through the gradual addition of trilete sub-crystals. The morphology of the dendrite crystals was controlled by flow direction and the competition for growth space with neighbouring crystals. Densely crowded dendrites with limited branching characterize the rimstone dams whereas widely spaced dendrites with open branching are found in the pools. Many dendrite bushes in the pools nucleated around plant stems. Growth of the dendrite crystals was seasonal and incremental. Calcite precipitation was driven by rapid CO2 degassing of CO2-rich spring waters during the spring and summer. During winter, when snow covered the ground and temperatures were low, opal-A precipitated on the exposed surfaces of the dendrites. Segmentation of dendrite branches by discontinuities coated with opal-A and overgrowth development around sub-crystals resulted from this seasonal growth cycle. The calcite dendrite crystals in the Lýsuhóll travertine differ in morphology from those at other hot springs, such as those at Lake Bogoria, Kenya, and Waikite in New Zealand. Comparison with the calcite dendrite crystals found at those sites shows that dendrite morphology is site-specific and probably controlled by carbonate saturation levels that, in turn, are controlled by the rate of CO2 degassing and location in the spring outflow system.  相似文献   

3.
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.  相似文献   

4.
温泉钙华沉积的影响因素   总被引:2,自引:2,他引:0  
钙华是在泉水、河水、湖水、洞穴周围沉积的非海相碳酸钙沉积物。钙华是陆地水循环过程中物质迁移的一种表现形式,研究钙华的形成有助于了解局部水文循环中的物质迁移规律并间接了解古气候与古水文地质条件。部分温泉的泉口附近沉积有形态多样的钙华。本文综述温泉钙华的形成过程、钙华沉积的主要影响因素和它们之间的相互影响关系。水化学条件是钙华沉积的物质基础和必要条件,水动力条件是钙华沉积的充分条件,生物效应对钙华沉积起到加强的作用,沉积环境通过影响水化学条件或水动力条件间接控制钙华的沉积。  相似文献   

5.
Late Quaternary travertines deposited from hot springs can reveal much about the neotectonic attributes and histories of structures. On the basis of field studies in the Aegean region (Turkey and Greece), the northern Apennines (Italy) and the Basin and Range province (USA) we conclude that the following relationships are of predictive value: (i) travertine deposits are preferentially located along fracture traces, either immediately above extensional fissures or in the hanging walls of normal faults; (ii) the locations of many travertine fissure-ridge deposits coincide with step-over zones (relay ramps) between fault segments; networks of intersecting tensional fissures reflecting the complex strains experienced in such settings are probably responsible for enhancing hydrothermal flow; (iii) the morphology of travertine deposits overlying extensional fissures is controlled by the rheology of the underlying materials; tufa cones (towers, pinnacles) form on former and present lake floors where fissures underlie unconsolidated sediments, whereas fissure-ridges develop where fissures cut bedrocks at the surface; (iv) fissure-ridges comprise outwardly dipping bedded travertine flanking a central tensional fissure filled by vertically banded travertines; fissures can be used to infer local stretching directions; (v) where there are travertines datable by the U-series method it is possible to calculate time-averaged dilation and lateral propagation rates for individual fissures; (vi) most fissures cutting fissure-ridges comprise self-similar angular segments with fractal dimensions in the range 1.00–1.12, the properties of bedded travertine combined with stress perturbations at fissure tips probably being responsible for such similar fractal dimensions being inferred from such a wide range of locations. Fissures gradually increasing in width with depth are products of continuous fracture dilation in contrast to those that form during episodic dilation which display stepped increases of width with depth; (vii) travertine deposited from springs along fault zones accumulate in terraced-mounds sited down slope of the spring line; (viii) many post-depositional fractures cutting travertine deposits are locally oriented at right angles to deposit margins; and (ix) systematic joints in travertines are restricted to those parts of eroded sheet deposits that have been exhumed.  相似文献   

6.
西藏多格错仁南岸钙华地球化学特征与钾盐地质意义   总被引:2,自引:0,他引:2  
西藏多格错仁南岸地区发育有一系列正在沉积的钙华丘和盐泉,泉水具有较高的含钾异常,属于含钾溶滤卤水,因此确定泉水中的矿物质来源成为找钾的关键问题,研究钙华的地球化学特征和成因机制则有助于解决这一问题。区内钙华有原地钙华和碎屑钙华两种类型,且明显富集K、Fe等元素,具有明显的轻稀土富集特征。不同泉眼周围的钙华样品的稀土分配模式基本相同,表明区内钙华的钙物质具有同一来源层位。经过将钙华与区内主要地层的稀土元素特征进行比对,发现这些钙华和索瓦组具有明显的亲缘关系,针对两者的相关性分析也再次表明钙华和索瓦组的亲缘特征。在此基础上,结合区内古地理和古气候资料,认为索瓦组具有较好的找钾潜力。此外,盐泉和钙华的碳、氢、氧同位素数据说明,盐泉的水物质属于大气降水,形成钙华的CO2则具有深部来源特征,研究区的钙华属热成因钙华。  相似文献   

7.
In this paper we describe an example of travertine fissure-ridge development along the trace of a normal fault with metre displacement, located in the eastern margin of the Neogene–Quaternary Siena Basin, in the Terme S. Giovanni area (Rapolano Terme, Italy). This morphotectonic feature, 250 m long, 30 m wide and 10 m high, formed from supersaturated hot waters (39.9°C) flowing from thermal springs aligned along the trace of the normal fault dissecting travertines not older than Late Pleistocene (24 ± 3 ka). A straight, continuous fissure with a maximum width of 20 cm occurs at the top of the ridge, along its crest. Hot fluids flow from cones mainly located at the extremities of the ridge, where travertine is depositing. The travertine fissure-ridge shows an asymmetrical profile since it buries the fault scarp. The difference in height of slopes corresponds to the vertical displacement of the normal fault. Fissuring of the recent travertine deposits along the strike of the crestal fissure, as well as recent hydrothermal circulation, lead us to believe that the Terme S. Giovanni normal fault may be currently active. On the whole, the Terme S. Giovanni fissure ridge can be defined as a travertine fault trace fissure-ridge, adding a helpful example for studying the relationship between faulting and travertine deposition.  相似文献   

8.
Travertine is present at 20% of the ca 60 hot springs that discharge on Loburu delta plain on the western margin of saline, alkaline Lake Bogoria in the Kenya Rift. Much of the travertine, which forms mounds, low terraces and pool‐rim dams, is sub‐fossil (relict) and undergoing erosion, but calcite‐encrusted artefacts show that carbonate is actively precipitating at several springs. Most of the springs discharge alkaline (pH: 8·3 to 8·9), Na‐HCO3 waters containing little Ca (<2 mg l?1) at temperatures of 94 to 97·5°C. These travertines are unusual because most probably precipitated at temperatures of >80°C. The travertines are composed mainly of dendritic and platy calcite, with minor Mg‐silicates, aragonite, fluorite and opaline silica. Calcite precipitation is attributed mainly to rapid CO2 degassing, which led to high‐disequilibrium crystal morphologies. Stratigraphic evidence shows that the travertine formed during several stages separated by intervals of non‐deposition. Radiometric ages imply that the main phase of travertine formation occurred during the late Pleistocene (ca 32 to 35 ka). Periods of precipitation were influenced strongly by fluctuations in lake level, mostly under climate control, and by related changes in the depth of boiling. During relatively arid phases, meteoric recharge of ground water declines, the lake is low and becomes hypersaline, and the reduced hydrostatic pressure lowers the level of boiling in the plumbing system of the hot springs. Any carbonate precipitation then occurs below the land surface. During humid phases, the dilute meteoric recharge increases, enhancing geothermal circulation, but the rising lake waters, which become relatively dilute, flood most spring vents. Much of the aqueous Ca2+ then precipitates as lacustrine stromatolites on shallow firm substrates, including submerged older travertines. Optimal conditions for subaerial travertine precipitation at Loburu occur when the lake is at intermediate levels, and may be favoured during transitions from humid to drier conditions.  相似文献   

9.
基于水化学和同位素特征的四川黄龙沟泉群分类研究   总被引:5,自引:3,他引:2  
本文采用水化学和同位素方法对四川黄龙沟沿途出露的7个泉点进行了分析.结果表明,泉水水化学和同位素的时空变化反映了CO2逸出、钙华沉积和蒸发效应等诸多因素的共同影响,是由这些泉水处在四个水循环转化段决定的.根据水化学和同位素特征可将这些泉水划分为三种不同的类型:深部泉、表生泉和转化泉.这些认识将为四川黄龙沟景观水资源的管...  相似文献   

10.
陆地热泉钙华研究进展与展望   总被引:1,自引:1,他引:0  
陆地热泉钙华是沉淀于富Ca2+和HCO3-热泉(普遍T≥30℃)的陆地碳酸盐沉积物/岩。热泉钙华独特的形成环境、岩石矿物学特征、地球化学特征和流体性质对古环境、古气候、早期生命起源、新构造运动、陆相热水沉积学、地热资源等方面研究具有重要指示意义。尽管相关学者对陆地热泉钙华开展了相关研究,但由于热泉钙华沉积-成岩过程中受复杂外界条件控制,其时空分布、沉积特征、矿物组成、地球化学特征、微生物作用、流体来源、成岩作用、古气候记录等系列科学问题有待深入研究。在国内外大量文献的基础上,结合研究团队对云南腾冲火山地热区热泉钙华的认识,综述了目前国内外学者对陆地热泉钙华的研究进展,总结了热泉钙华研究意义,提出了当前热泉钙华研究存在的问题及下步研究方向,为更加全面地认识陆地热泉钙华沉积及未来研究提供启示。  相似文献   

11.
. Pamukkale protected site is located 20 km away from the provincial center of Denizli in southwest Turkey. This site has unique natural and cultural assets such as hot water springs, white travertine terraces, and cultural ruins of the ancient city of Hierapolis. The rising interest in this site leads to irreversible deterioration of natural and cultural assets. This study reveals the environmental issues, such as swimming activities, the lack of sewage treatment, mechanical damage, etc. on hot water springs and white travertine terraces. Swimming activities in the pools and sewage leakage from non-isolated cesspools encourage excessive microbial growth at the travertine surface resulting in the discoloration of white travertine terraces. Walking over the delicate travertine surface leads to the deformation of existing calcite crystals and delays the formation of the new crystals. Vehicle entry to the site causes damage, for example creating vibration, high gas emission, and dust airlifting. To ensure optimal protection conditions at this site, priority must be given to the maintenance, restoration, monitoring, and maximization of the natural resources, and special regulations and laws should be enacted. Although it must be realized that good resource management will never be able to completely solve the problems in conservation of this site, it is equally clear that a correct use of natural resources can help avoid worsening of an already difficult situation.  相似文献   

12.
Late Pleistocene travertines up to 40 m thick near Rapolano Terme in Tuscany, central Italy, were precipitated by hot water issuing from springs on hillsides and flowing into adjacent depressions to mix with rainwater. Proximal light-coloured slope and terrace travertines pass distally into darker reed mound and depression-fill travertines. Lithotypes include crystalline crust, shrub, pisoid, paper-thin raft, coated bubble, reed, and lithoclast-breccia. High precipitation rates resulted in rapid slope aggradation and progradation. Dilution by rainwater likely lowered precipitation rates in depressions, but deposition was augmented by allochthonous material eroded from upslope travertines. Slope Depositional Systems consist of Smooth and Terrace Slope facies characterized by white crystalline crusts, with diverse additional lithotypes in terrace pools. Depression Depositional Systems have mixed light and dark travertines with horizontal to gently concave stratification. Extensive light-coloured Shrub Flat travertine is dominant; darker Marsh-Pool Facies composed of fine lithoclast and reed travertine is localized. Reed Mounds composed of mixed light and dark travertines localized by abundant reed growth, formed where spring water emerged near the bases of low angle slopes. Distal reduction in accretion rate was the major influence on sequence development. Light-coloured slope travertines interdigitate with darker depression deposits. Vertical aggradation of slope deposits, mound progradation, and filling of topographic depressions is expressed by advance and retreat of facies. Evolution from depression to slope or mound sequences is termed ‘steepening up’. Up-sequence change from slope or mound to depression facies is termed ‘levelling up’. Exposure surfaces associated with palaeosols are common in all facies and often constitute sequence boundaries. They are more closely spaced in depression sequences, reflecting slower and possibly also more discontinuous accumulation at sites furthest from hot springs.  相似文献   

13.
本文通过调查黄龙风景区水体的环境地质特征与微生物群落结构及多样性,并与黄石公园对比分析,探讨了两种特殊地理环境下的微生物群落结构和多样性及其对钙华沉积的影响.结果表明:黄龙沟泉水属于地下冷泉,且景区内覆盖着大量植被,水体中有大量藻类和细菌;黄石公园猛犸象温泉区泉水属于地下热泉,植被覆盖率很低,泉水中微生物多为嗜热菌,藻...  相似文献   

14.
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.  相似文献   

15.
In the periods 1980–1986 and 1990–2007 many boreholes were sunk during hydrogeological investigations in the center of the Karlovy Vary (Carlsbad) hot spring system. The extent and the depths reached were the greatest in the history of the geological investigation of the discharge area of the thermal system. The results of the drilling program enabled a detailed study of the rocks, groundwater and spring sedimentation in the area as well as the preparation of new proposals for changes in the spring-protection zones. The spring sedimentation consists of world-renowned hot spring travertine, with a wide range of morphological varieties of different origins and of different ages. The oldest U-series age data (230 ± 14 ka BP) have been obtained for travertine relicts located 22 m above the present-day bottom of the narrow valley of the Teplá River. Five other travertine deposits, partly overlapping in space and time were identified on the bottom and slopes of the valley. They were formed by gradual growth, by river erosion and since the fourteenth century by human activities.  相似文献   

16.
《地学前缘(英文版)》2020,11(5):1549-1569
The principal features,geotectonic settings and association with near-surface hydrothermal mineral systems of ancient and present subaerial hot springs,fumaroles and geysers are herein reviewed.Fumaroles and geysers usually occur in volcanic craters and are in most cases,part and parcel of hot spring environments.Subaerial hot springs are characterised by siliceous-and carbonate-rich chemical sediments,such as sinters and travertines,respectively.Sinters are commonly enriched in various metalliferous elements.Hot springs surface discharges are also characterised by pools,which exhibit bright colours due to the presence of microorganisms.Present-day examples discussed in this paper,include the fumaroles and hot springs of the White Island volcano(New Zealand),the world-renowned Yellowstone caldera(USA) and the Afar region of the East African Rift System.The Afar triangle,in the northern part of East African Rift System,provides a good example of hot springs associated with evaporative deposits.The Tuli-Sabi-Lebombo triple junction rifts were formed during the ~180 Ma Karoo igneous event in southern Africa,of which the Tuli arm is the failed rift(aulacogen),as is the Afar region.The Tuli rift is effectively an unusual,if not unique,tectono-thermal setting,because it comprises Karoo-age hot springs systems and associated vein stockworks and breccias,which includes the Messina Cu deposit as well as currently active hot springs with sinter deposits probably due to post-Karoo uplift.Fumarolic pipes in ignimbrites of the Erongo Volcano-Plutonic Complex in Namibia are discussed.This is followed by an example of banded chert rocks in the Killara Formation of the Palaeoproterozoic Capricorn Orogen(Western Australia),interpreted as hot spring chemical sediments,which also show evidence of "fossil" microbial filaments.The paper ends with a brief overview of possible analogues of hot springs on planet Mars.  相似文献   

17.
为研究四川省康定市二道桥地区地下热水稳定同位素特征和热储温度,对二道桥地区5个温泉(井)即二道桥温泉(SC107、SC107-2)、康巴人家温泉(SC107-3)、自流热水井(SC107-4)、自喷热水井(SC107-5)进行调查和分析。研究区温泉的分布及出露主要受雅拉沟断裂和雅拉河谷控制。温泉水温33.2~46℃,为中低温温泉,pH为6~6.5。水样的氢氧稳定同位素特征表明研究区地下热水的补给来源为大气降水。利用氢氧稳定同位素高程效应及温度效应估算区内地下热水补给区高程为3 000~4 500 m,补给区温度为-3.5~-0.3℃,表明地下热水有一部分补给源自附近山区的冰雪融水。Na-K-Mg三角图显示研究区热水均为未成熟水,不宜用阳离子地热温标计算热储温度。应用SiO2地热温标、多矿物饱和指数法以及用固定铝方法对部分温泉多矿物平衡图进行修正,得出研究区地下热水的热储温度为65~75℃。研究区温泉在东部跑马山以及西部农戈山附近接受大气降水补给,降水沿着大雪山—农戈山断裂和跑马山断裂下渗,地下水经历深循环,在此过程中获得大地热流加热,最终在雅拉河谷雅拉沟断裂附近出...  相似文献   

18.
以我国大陆范围内典型的岩浆热源型水热系统——云南腾冲热海为研究区,在国内首次对热泉中硫代砷化物含量及其地球化学成因进行了分析.研究采用的在野外对富硫化物水样进行快速冷冻处理、而后在实验室进行砷的形态分离和测试的方法明显优于当前通用的水样砷含量及其形态分析的预处理和测试方法.主要原因为后者在采样现场对水样的酸化处理可使样品中三硫代砷酸盐以非定形态硫砷化合物的形式沉淀,且用常规阴离子交换柱在野外无法实现硫代砷酸盐的完全回收及其与砷酸盐的分离.受岩浆流体输入和热储内高温条件下强烈流体-岩石相互作用的控制,热海水热系统排泄的中性-偏碱性热泉中富集硫化物和砷,为热泉中硫代砷化物的形成提供了必要条件.热海热泉中检出的硫代砷化物包括一硫代砷酸盐、二硫代砷酸盐和三硫代砷酸盐,在总砷中所占比例最高分别可达26.7%、43.3%和33.7%.热海地热田的2个子区(硫磺塘和澡塘河) 的热泉沿不同断裂带出露,地热水升流过程中经历的冷却方式也不同,使硫磺塘热泉具有相对较高的总硫化物含量和总砷含量,并导致其中各类硫代砷酸盐具有更高的含量范围.   相似文献   

19.
A multidisciplinary characterization of an active thermal spring in central Italy has been undertaken with the aim of (i) ascertaining whether microbiological activity plays a relevant role in hot-depositing travertines and (ii) establishing an experimental protocol able to identify similar effects in fossil travertines. Water, gas, and travertine samples were investigated by chemical (ICP/MS, SEM/EDS), physical (DTA-DTG), isotopic (δ18O, δD, and δ13C), mineralogical (XRPD), and spectroscopic (EPR) techniques. Twenty-four samples (three for each phase) were collected every 5 °C temperature drop, along a ∼100 m long artificial channel near Viterbo (Bullicame 3, Latium, central Italy). A microbiological characterization was carried out in parallel, sampling the channel every 10 °C temperature drop.The Bullicame 3 system is revealed to be composed of two markedly different subsystems: a water/gas interface, where a kinetically fast exchange allows equilibrium of components both in water and in gases; a solid/water interface, where travertine precipitation occurs, influenced by microbiological activity. A peculiar lattice shrinking of calcite was identified, as well as an anomalous value of the zero-field splitting parameter from the EPR measurements. The interpretation of these anomalies is confirmed by the identification of calcifying cyanobacteria throughout the channel path.Our results point out that microbiological activity can play a significant role in travertine deposition from hot springs. Furthermore, the proposed approach, representing a tool to identify crystal chemical remnants of past microbiological activity, could be applicable to fossil travertines.  相似文献   

20.
研究目的】陆地热泉钙华作为火山、地热区常见的陆相碳酸盐岩沉积物/岩被广泛用于恢复古环境,但其中可反映古气候信息的代用指标多受复杂外界条件变化控制,因此利用热泉钙华进行古气候信息提取有待深入研究。【研究方法】本文对当前热泉钙华在重建古气候信息方面的成功案例进行了总结,并梳理了与热泉钙华沉积相关的各类气候、非气候影响因素。【研究结果】研究认为针对热泉钙华进行古气候恢复代用指标的选取,目前较为可行的有C-O同位素、主微量元素,孢粉学数据由于孢粉保存的局限性,可作为佐证信息,配合其他气候代用指标来检验古气候意义的正确与否,同时需将热泉钙华中各项气候代用指标与生物地层学、冰芯、石笋等相对成熟的古气候研究手段进行对比,使各类古气候替代指标相互验证,从而更好的解读热泉钙华中古气候信息。【结论】利用热泉钙华中的各项气候代用指标进行可靠的古气候信息提取与恢复具有可行性。创新点:本文梳理了国内外热泉钙华恢复古气候的成功案例,并探讨了针对热泉钙华进行古气候恢复研究存在的问题。  相似文献   

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