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THE EVOLUTION OF THE COVERED KARST AND TECTONIC UPLIFT OF HU'NAN, GUANGXI, GUANGZHOU, YUNNAN AND TIBETthedevelopmentprojectofNationalKeyFoundation (G 19980 40 80 0 ) ;theprojectofTibetPlateaure
searchofChineseAcademy (K2 95 1 A1 相似文献
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岩溶夷平面演化与青藏高原隆升 总被引：10，自引：5，他引：5
文章以作者在青藏高原南部及东邻地区获得的资料为基础,就青藏高原地区夷平面的识别、整体坡降、时代以及夷平面对构造隆升的响应等问题进行讨论。区域对比与成因分析显示青藏高原石林等形态形成于土下环境,属覆盖型岩溶,而与其共存的红色风化壳(石灰土)具有脱硅富铝作用弱而粘化作用强的特征,与湿热气候条件下的夷平面环境是一致的。根据野外观察资料和岩溶作用对水动力条件的敏感性,岩溶区厚层连续的风化壳只能发育在接近地貌侵蚀基准的夷平面上。因此,厚层连续的风化壳及其壳下的覆盖型岩溶均可指示地貌发育的晚期阶段和夷平面的存在,这为利用覆盖型岩溶及共存的风化壳识别夷平面提供了理论依据。根据青藏高原东邻地区岩溶地貌发育的演化特征,作者认为在同等条件下,岩溶夷平可以在更短的时间里达到更低的夷平高度(相对常态夷平),初步估计岩溶夷平面整体坡降小于0.5‰。构造隆升使青藏高原进入不利于岩溶作用的寒冻圈,岩溶夷平面经刻蚀作用演变为刻蚀平原,而云贵高原刻蚀作用较弱,但受到“土壤丢失”等岩溶过程的破坏。这种差别主要是构造隆升幅度的不同造成的。为了解决夷平面的年代问题,作者对滇西表生锰氧化物40Ar39Ar测年适宜性作了研究,结果显示鹤庆等地表生锰矿具有较 相似文献
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云贵高原碳酸盐岩风化壳的古地磁定年探讨 总被引：2，自引：0，他引：2
云贵高原乃至中国残积型红土及红土性风化壳的形成年代是一个长期以来悬而未决的问题。本文以云贵高原厚度分别为9. 47m 和5. 4m的两个碳酸盐岩风化剖面为例,探讨了古地磁方法在碳酸盐岩风化剖面定年中的应用。古地磁定年结果初步表明,其发育时间在布容正极性世内,即两个风化壳剖面的发育年龄不会大于0. 78Ma B. P. 。此外,对古地磁方法应用于碳酸盐岩风化剖面定年中可能存在的问题进行了讨论,其中包括风化壳的成因、风化过程中的体积变化、母岩的岩石磁性、磁性载体矿物及其记录磁信号的稳定性等问题。 相似文献
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通过与粉尘堆积,以及玄武岩和片麻杂岩风化剖面磁组构的对比,探讨了以贵州平坝白云岩之上红色粘土剖面磁组构特征及其成因指示意义。红色粘土的各向异性较弱,并且不具有明显的沉积磁组构;母岩的组构特征对红色粘土磁化率各向异性没有明显的控制“痕迹” ;红色粘土与粉尘堆积物之间磁组构特征的明显差异,表明它们在物源和形成机制方面是不同的;红色粘土磁化率及磁组构特征反映出红色粘土中磁性矿物的物质来源和成因具有一定的特殊性。 相似文献
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The purpose of this study was to determine and evaluate the geochemical characteristics of the limestone of the Upper Cretaceous Mortas Formation and related terra rossa in a 50 km2 area which is located 20 km south of the city of Seydisehir, Central Anatolia, by using data obtained from the ICP-MS analysis of randomly collected 42 samples of limestone and 18 samples of the terra rossa.The limestone of the Mortas Formation is composed of fossilliferous, gray-cream colored, medium to thick bedded, partially dolomitic carbonate rocks, and generally has dismicrite, intrapelmicrite composition. It includes the largest bauxite reservior in Turkey and has many occurences of terra rossa formation on it. According to mean distance, the Ba, Be, Hg, Mo, Nb, Sb and Th concentrations in the limestones overlying and underlying the bauxite deposits are different, but the main oxides, REE and other trace elements are same. In factor analysis, the first component reflects relative enrichment of clay against to CaO contents of the limestone, the second component corresponds to the degree of dolomitization. The PAAS-normalized REEs pattern for the Mortas Formation limestone samples illustrate similar main features as seawater.The terra rossa soils in the study area are considered to be highly weathered and weakly mature soil with respect to their generally low Al2O3 (21%), but high CaO (2%) contents, and their alteration indices. The element ratios in the terra rossa and limestone show that in the process of the transformation from limestone to terra rossa, Ba, Si, Ti, Al and Fe were enriched together by staying in-situ. Except Ce, all lanthanides show similar behavior, but the HREE, which were richer in limestone, were consumed fast relative to the LREE during soil formation. The association and the enrichment of Co, Cu, Cr, Ni and Pb as well as Ba, Zr, Ga, Nb and Rb in soil relative to the limestone are interpreted as being resulted from eolian transportation. Ca, Au, Hg, Sr, Se, Sb, Mo, Ag, U, Cd and Na were found to be the most mobile elements during pedogenic transformation. According to main oxide composition ratios of the limestone and terra rossa, the soils were described as representing a well washed soil completing the leaching and accumulation phase, but not totally completing the silicate weathering phase. In the processes of soil formation, 97.76% of the limestone was washed away; only 2.24% of limestone was deposited as soil. Therefore, 61 times mass reduction was realized. 相似文献
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南方红土是我国热带、亚热带以各类岩石和第四纪松散沉积物为母质发育的红色风化壳,也是我国分布最广的第四纪土状堆积。本文在探讨第四纪松散沉积物上红色风化壳的形成机制的基础上,根据风化壳发育程度将其划分为砖红土风化壳、红壤土风化壳和红化土风化壳3种类型。南方地区第四纪松散沉积物主要有河流相沉积、滨海相海滩砂和海岸风成砂——"老红砂"以及以下蜀土为主的风尘堆积。近年来在上述沉积物中多处发现旧石器遗址,促进了南方红土的地层年代学研究。根据前人及近期对南方红土的研究成果,讨论了南方红土的年代地层学问题,提出了以风化壳岩性特征为基础的岩石地层单位初步划分框架:老红砂划分为中更新统北海组、晚更新统晋江组;风尘堆积划分为中更新统宣城组、晚更新统下蜀组;河流相沉积只划出中更新统白沙井组,晚更新统留待以后研究再划出。 相似文献
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The mobilization, redistribution and fractionation of trace elements during chemical weathering processes have been investigated on a 4.05 m thick terra rossa profile overlying dolomite on the Yunnan-Guizhou Plateau, in Southwest China. In this in situ weathering profile, the ferromanganese concretions and the gibbsite spots coexist in the terra rossa saprolite. The mass-balance evaluation reveals that titanium, Nb and Hf in the terra rossa matrix are conservative elements during chemical weathering compared to Zr. The elements of Li, Sc, V, Cr, Fe, Ga, As, Mo, Cs, Ce, Ta, Tl, Pb and Th in the terra rossa matrix include additions from external sources. Beryllium, Mn, Co, Ni, Cu, Rb, Ba and La are depleted in the shallow parts of the terra rossa profile and enriched in the deep parts. The elements of Zn, Sr, Y, Cd, Sn and U in the terra rossa profile are lost during weathering. Compared to the terra rossa matrix, the ferromanganese concretions are significantly enriched in most trace elements, especially Mn, Co, Cd, Ce, Tl and Pb. In contrast, the gibbsite spots are depleted in all trace elements, except for U. The results regarding specific inter-element relationships indicate that most trace elements have different inter-element relationships in the ferromanganese concretions, the gibbsite spots and the terra rossa matrix. This suggests that the behavior of many trace elements during mobilization and redistribution differs from their behavior during incorporation into secondary mineral phases, especially the Mn and Fe oxides and/or oxyhydroxides in the ferromanganese concretions. It is worthy to note that the fractionation between Ce and Mn occurs under intensive chemical weathering conditions. Correspondingly, beryllium exhibits a similar geochemical behavior as that of rare earth elements (except for Ce) and Y during surface weathering. 相似文献
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The lanthanide tetrad effect was investigated in a 5.4 m thick terra rossa profile overlying dolomite on the Yunnan-Guizhou Plateau, China. The results demonstrate that the chondrite-normalized rare earth element pattern of dolomite bedrock displays a W-type tetrad effect. The insoluble residue from the dolomite bedrock does not exhibit any significant tetrad effect. In contrast, some ferromanganese concretions and the terra rossa show tetrad effect. It is worth noting that the conjugate M- and W-types of the tetrad effect are observed in some terra rossa samples. The tetrad effect in the ferromanganese concretions and the terra rossa possibly originates from redistribution of dissolved rare earth elements during their downwards movement in the profile and not only from water/rock interaction. Within the dolomite weathering system, the ferromanganese concretions and surrounding terra rossa present similar correlations of Eu/Eu*, Y/Ho, Sm/Nd, Ce/Ce*, with the size of the tetrad effect. The ferromanganese concretions and the terra rossa with tetrad effect are characterized by a reduced, non-chondritic Y/Ho ratio. Also the Y/Ho ratio exhibits a clear negative correlation with the size of the tetrad effect in the ferromanganese concretions and the terra rossa. In addition, the Eu/Eu* tends to increase with increasing size of the tetrad effect in the ferromanganese concretions and the terra rossa, as does the Sm/Nd ratio. The regular variation for Eu/Eu*, Y/Ho and Sm/Nd is likely a result of the fractionation of rare earth elements and yttrium with the tetrad effect. On the other hand, the correlation of the Ce/Ce* with the size of the tetrad effect in the ferromanganese concretions and the terra rossa is random. This likely indicates that the Ce behavior within weathering system is mainly controlled by redox condition, rather than tetrad effect. Comparative study indicates that the correlations of Eu/Eu*, Y/Ho, Ce/Ce*, with the size of the tetrad effect in the ferromanganese concretions and the terra rossa, are not similar to those found in a highly evolved igneous system. Nevertheless, the correlation of Sm/Nd with the size of tetrad effect in weathering system is similar to that in igneous system. In general, it appears to indicate that the tetrad effect occurrence in granitic rocks is not associated with weathering. 相似文献
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Preliminary study on development characteristics of planation surface in Liaodong Peninsula 
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下载免费PDF全文 Planation surface is one that is associated with long-term stable tectonic environment of large scale landscape. The planation surface with the weathering crust as a whole to study is the main stream of modern planation surface research. The red weathering crust mainly is outcropped in the east and west of Liaodong Peninsula,and its thickness is around 4 m. In order to explore the properties,environment and development characteristics of the planation surface in Liaodong Peninsula,chemical elements and particle size characteristics of red weathering crust in this area were studied. The test results showed that the average value of CIA of the red weathering crust in the study area is 82.70,the average value of ba((Na2O+K2O+CaO+MgO)/Al2O3)is 0.39,the average value of S/A(SiO2/Al2O3)is 4.86,and the average value of clay content is 8.31%. Compared with the red weathering crust of the karst area in the south of China,it has the characteristics of low leaching rate of salt base,low aluminization degree and weak viscosification. According to the regional geomorphologic features,the development of red weathering crust in the study area mainly went through four stages: (1)karst process was carried out in the whole rock mass above the base level of ancient erosion,and the geomorphologic fluctuation gradually increased;(2)geomorphologic fluctuation reached the maximum,and covered karst and gray weathering crust began to develop;(3)karst double-layer planation surface basically formed;(4)the development of gray weathering crust nearly stopped. With the tectonic movement,the gray weathering crust,which was originally located below the base level of ancient erosion,was all elevated above the base level of modern erosion to form red weathering crust. Therefore,the planation surface in the study area is ancient planation surface,and the development stage is lateralization stage. The results can provide a preliminary basis for revealing the neotectonic movement and sea level change in the Liaodong Peninsula from the Neogene to present. 相似文献
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夷平面是一种与长期稳定的构造环境相关联的大尺度地貌景观,将夷平面与风化壳作为整体来研究是现代夷平面研究的主流。为了探讨辽东半岛夷平面的性质、形成环境等发育特征,对该地区的红色风化壳进行地球化学分析和粒度测试。辽东半岛红色风化壳主要出露于半岛东西两侧,厚度多在4 m左右,化学蚀变指数CIA平均值为82.70,ba值((Na2O+K2O+CaO+MgO)/Al2O3)平均为0.39,S/A值(SiO2/Al2O3)平均为4.86,黏粒含量平均为8.31%。从分析数据可以看出,辽东半岛红色风化壳是下伏基岩原地风化的产物,推测其形成于温暖、湿润的气候条件下,与南方岩溶区红色风化壳相比具有盐基淋溶率低、富铝化程度低和黏化作用弱的发育特征。结合区域地貌特征,认为研究区红色风化壳的发育主要经历了4个阶段: (1)岩溶作用在古侵蚀基准面之上的整个岩体内进行,地貌起伏逐渐增大;(2)地貌起伏达到最大,覆盖型岩溶、灰色风化壳开始发育;(3)岩溶双层夷平面基本形成;(4)灰色风化壳的发育近乎停止,原本位于古侵蚀基准面之下的灰色风化壳在构造运动作用下全部抬升于现代侵蚀基准面之上形成红色风化壳。因此,研究区的夷平面为古夷平面,发育阶段为红土化阶段。该研究成果可为辽东半岛新近纪以来的新构造运动及海平面变化研究提供初步依据。 相似文献
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This study presents bulk chemical compositions of the Tongmuling soil profile, which developed on dolostone, and the overlying strata covering the bedrock in the central Guizhou province (southern China). The chemical weathering characteristics of the studied profile were investigated and the inheritance relationships between the terra rossa and overlying strata were discussed. The results show that there is no remarkable variation in the major elements and weathering indices from the rock–soil interface to the topsoil, indicating that the studied profile was not typical for in situ crustal chemical weathering. The terra rossa were mainly composed of SiO2, Al2O3 and Fe2O3. Compared with the insoluble residues and overlying strata, the terra rossa are characterized by an enrichment of Y and Cs and depletion of Ba and Sr. The subsoil shows a notable Ce negative anomaly, characterized by heavy rare earth element enrichment (L/H = 1.55–3.74), whereas the topsoil shows a positive Ce anomaly with light rare earth element enrichment (L/H = 5.93–9.14). According to Laterite-forming capacity estimates, the terra rossa could not have only been formed from acid-insoluble residues from the bedrock; Al2O3 versus Fe2O3 and Nb plotted against Ta show significant positive correlations between the terra rossa and overlying strata. The Eu/Eu* versus GdN/YbN and ternary diagrams for Sc, Th, Zr, and Ta suggest that the overlying strata could also provide parent materials for the genesis of terra rossa. 相似文献
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石灰岩山地淡竹林“岩石-土壤-植物”的元素分布与迁移积聚特征 总被引：1，自引：0，他引：1
本研究以石灰岩山地淡竹林为研究对象,测定了岩石、土壤和4种淡竹群落植物[优势种淡竹(Phyllostachys glauca),伴生种枸骨(Ilex cornuta)、油茶(Camellia oleifera)和胡颓子(Elaeagnus pungens）]的N、P、K、Ca、Mg、Fe、Al、Mn和Na等9种元素含量,对元素迁移积聚特征进行了分析,结果表明:（1）淡竹林石灰岩Ca含量高（363.09 g· kg-1）;土壤Ca含量下降至2.68 g·kg-1,Fe、Al含量升高（48.12 g·kg-1、84.00 g·kg-1）;与土壤相比,植物N、P和Ca含量上升,其他元素含量则降低;（2）从岩石到土壤,Ca为纯迁移,迁移积累系数仅为0.01;Fe和Al明显富集,迁移积累系数分别高达9.98和14.10;从土壤到植物,N、Ca、P为富集,Fe、Al生物吸收系数很低,仅为1.41和2.08;（3）除K外,群落优势种淡竹的元素含量和生物吸收系数均小于伴生种。研究发现,强淋溶作用下淡竹林石灰岩发育为酸性红石灰土,其生长的植物均非喜钙植物;“岩石—土壤—植物”元素迁聚特征因土壤发育过程和植物种间特征而异,红石灰土Ca积累少;淡竹对土壤元素需求少可能是其在石灰岩生境占据竞争优势的生理基础。 相似文献
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豫西济源西部铝土矿成矿地质环境 总被引：17，自引：0，他引：17
文章在对含矿岩系岩石组合、地球化学分析的基础上,认为矿区铝土矿形成于华北地块从早古生代准平原状态向晚古生代陆表浅海过渡时期,早期海侵之后的陆地湖泊环境中.被碳酸盐岩覆盖、较小地形差异的陆地准平原状态,湿热的气候,繁茂的植物使得岩溶湖泊成为铝土矿富集和保存的有利场所. 相似文献
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微地域搬运——碳酸盐岩红色风化壳形成过程的一种方式 总被引：1，自引：0，他引：1
由于差异溶蚀作用,由碳酸盐岩强烈风化形成的红色风化壳通常表现出独特的剖面构型:风化壳发育深厚、下伏基岩面强烈起伏波动、溶沟和石牙相间展布。以黔中岩溶台地之上发育的红色风化壳——平坝剖面为例,通过宏观地质、地球化学、粒度分析以及矿物学等方法,并以邻近的两个石灰土剖面(罗吏剖面和龙洞堡剖面)作对比,对碳酸盐岩红色风化壳的形成过程进行了讨论,论证了微地域搬运是碳酸盐岩红色风化壳尤其是厚层红色风化壳形成过程的一种方式。溶沟部位的风化壳,从风化前锋向上的一定深度范围内,为原位残积风化的产物(残积层);在此深度以上的部分,为地势较高的相邻石牙部位不同风化程度的残积物的搬运堆积(堆积层),也是导致风化指标随深度呈锯齿状波动的直接原因。后者一般组成剖面的主体。风化壳的年代地层学表现为,在残积层,从风化前锋向上,风化年龄由新到老;在堆积层,从下到上,风化年龄由老到新。风化前锋是一个重要的地球化学作用场所,在这一狭窄的界面上,伴随碳酸盐矿物的快速淋失,残余酸不溶物开始了明显分解。而风化壳的后期演化是一个缓慢而长期的过程。达到重力平衡的剖面(即风化壳表面平缓、不发生微地域搬运的剖面),在由表及里的风化作用下,从地表向下的一定深度范... 相似文献
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本文根据类似荒漠境况的出现是判断荒漠化发生与否的重要标志这一原则,并结合在中国南方开展的一些研究,对湿润地区的荒漠化进行了初步的探讨。研究表明,湿润地区的荒漠化并不包含所有存在侵蚀作用的退化土地,而专指人为侵蚀作用导致的出现了具类似荒漠境况的退化土地。中国南方湿润地区土地荒漠化分布最显著的特征为斑点状分布于丘陵山区或河、湖、海滨的冲积平原,面积为1．98×105km2,其中流水作用导致的荒漠化面积为1．78×105km2,风力作用的为0．11×105km2,其它0．09×105km2。自然因素,特别是气候和地貌因素对荒漠化的形成和发展起着积极的影响作用,但不是决定作用。人为不合理的经济活动,才是造成荒漠化的主要原因。文章最后还简要介绍了湿润地区荒漠化的防治问题。 相似文献
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Michele Spizzico 《Hydrogeology Journal》2005,13(3):493-505
High concentrations of 222Rn have been found throughout the waters of the coastal carbonate-rock Mesozoic aquifer located in the region of Apulia in southern Italy. Studies undertaken have determined that such concentrations are due to the radioisotopic features of terra rossa, a type of paleosol that is generated as a residual byproduct of carbonate dissolution and is found to be widespread throughout the aquifers fissures and karst cavities.These special types of soil feature a rather high clay content (80–95%) and, although variable, their specific 226Ra activity (70–147 Bq/kg) is nonetheless considerably greater than that of limestone (~50 Bq/kg). In fact, there are substantial differences in 222Rn concentrations found in waters that come into contact with this type of rock and paleosol.The partial dissolution of some carbonate rock samples in the laboratory confirmed that the 226Ra released by the dissolved rock primarily accumulates in the residual soil deposits, especially in ones containing finer granules. This has also been the result of experiments conducted on 15 terra rossa samples collected from the region, which indicates that there is a close correlation between the specific 226Ra activity and the clay content of such paleosols, which varies with the stage of weathering.It has been found that the 222Rn concentrations in the regions waters, depend on the specific terra rossa 226Ra activity rather than on the quantity of terra rossa.Field checks have confirmed the possibility of using 226Ra and 222Rn as natural tracers in order to define hydrogeological problems in special environments such as karst. They can be used to distinguish the different water bearing zones in the carbonate-rock aquifer; analyze the influence of tides on coastal springs; determine the flow direction in the proximity of a well; recognize, recharge and the progressive decline of the groundwater level; derive indications of underground flow paths; and the occurrence of fissures and karstic cavities in the carbonate-rock aquifer.
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| Michele SpizzicoEmail: Phone: +39-080-5963676Fax: +39-080-5963675 |
20.
THE ORIGIN OF DOUBLE HIGH CONDUCTIVITY LAYERS IN THE CRUST OF SOUTHERN TIBET AND ITS GEODYNAMIC CONSEQUENCE 相似文献