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红色风化壳记录着红土形成以来的古环境和古气候变化等重要信息，对全球气候变化的研究具有重要意义。碳酸盐岩风化成土地球化学过程和演化特征研究是岩溶环境中元素地球化学循环的重要组成部分和表生资源与环境研究的基础。目前对于碳酸盐岩上覆红色风化壳的研究还存在着以下几个问题：（1）红色风化壳的形成机制尚有争议；（2）研究大多集中在亚热带、温带地区，对于红色风化壳发育强烈的热带地区较少涉及；（3）红土元素的地球化学过程与气候变化的关系研究尚待完善；（4）白云岩和灰岩上覆红色风化壳的对比研究缺乏系统性资料。为了揭示热带地区碳酸盐岩上覆红土的物质来源、地球化学特征基于气候环境的关系，本文首先在越南北部选择12个发育在碳酸盐岩之上的红土剖面，通过野外宏观证据、土壤理化性质、元素地球化学等方法，探讨了越南北部红土成因机制，建立了碳酸盐岩成土的过程模型；然后利用两个典型的白云岩和灰岩剖面的元素迁移活化特征，红土化信息及Sr同位素证据等，揭示了红土剖面的地球化学演化规律；其次从风化程度、元素含量、粒度分布等方面对这两个典型的白云岩和灰岩剖面进行了对比，分析了这两个剖面的分异特征、演化过程及控制因素；最后通过烧失量及稀土元素的地球化学研究，阐明了红土形成及演化过程中的环境因素，探讨了剖面元素的地球化学分异和富集规律、红土的成因机制及与气候环境的关系，并利用Rb/Sr比值、δ13C、δ15N及14C重建了越南北部更新世至全新世中期的古气候变化。本研究主要得到以下几点认识：（1）越南北部碳酸盐岩上覆红土物质主要来自于下伏基岩，是碳酸盐岩原位风化的产物从宏观证据来看，越南北部碳酸盐岩上覆红土土层结构清晰，分层明显，保留了原有的基岩的残余结构特征；从主量元素和微量元素地球化学判据上来看，剖面无外来组分的加入，是原地风化剖面特征的体现；从粒度分布曲线上来看，红土剖面表现出粗粒峰和细粒峰，体现了对原岩的继承和风化的正向演化；矿物成分从基岩中的白云石、方解石到岩土界面的伊利石、斜长石再到红土中的高岭石、蒙脱石、绿泥石以及三水铝石等，显示物质来源的连续性。（2）白云岩和灰岩风化红土具有相同的剖面特征，但是其岩土界面结构、风化强度及矿物成分等不同首先，越南北部白云岩和灰岩风化演化过程中，体积变化巨大，每形成1m厚的土层，需要白云岩约50m，灰岩约100m；其次，受岩溶裂隙发育的影响，两种基岩的风化过程前缘均凹凸不平，红土剖面也均很好的保留了基岩的微层理结构；再次，两者的矿物均是从可溶性的碳酸盐逐渐转变成不可溶的硅酸盐黏土矿物的过程。但是两个剖面也有明显的区别，表现在：白云岩的岩土界面很容易形成岩石破碎带和岩粉层，而灰岩大多在岩土界面形成一层深褐色的巧克力层（淋溶淀积层），少量的灰岩岩粉层出现在含白云质和孔隙发育的灰岩剖面中，并且白云岩红土的风化强度通常高于灰岩。（3）相比硅酸盐岩及中国亚热带碳酸盐岩红土过程，越南北部碳酸盐岩风化成土具有特殊的演化规律越南碳酸盐岩铁、铝和硅的地球化学演化可以分为三个阶段——富硅脱钙镁阶段，富铝脱硅阶和深度红土化作用阶段；从基岩到上部土层，Al2O3、Fe2O3逐渐增加，CaO、MgO急剧减少，SiO2从岩石到土壤骤然增加，随后不断减少。而微量元素的变化表现出三种趋势：即波动、略有降低及稳定变化的趋势，对应元素的迁移的稳定、亏损和富集过程；从基岩到岩土界面再到土层，风化程度的不断加强，其强度比中国亚热带湿润气候条件下发育的红土更高；87Sr/86Sr随深度增加逐渐递减，是受剖面中含钙矿物（如高岭土）和含钾矿物（如伊利石）淋溶作用控制。（4）越南北部白云岩和灰岩风化剖面具有明显的地球化学分异特征白云岩红土化脱硅作用弱于灰岩风化剖面，而其富集铝的作用强于灰岩；白云岩在A—CN—K的三角图上投点大多位于伊利石的上方，显示经历了强烈的风化作用，而石灰岩风化剖面的投点大多位于伊利石的下方或接近伊利石，表明灰岩的风化作用还未达到强富铝阶段。由于越南北部白云岩中白云石平均含量约为22%，其孔隙率发育较快，溶蚀能力较强。此外白云岩中的酸不溶物成分平均为4.36%，而灰岩中的酸不溶物成分为1.78%，这也是白云岩的成土厚度高于灰岩的原因。从粘粒含量来看，白云岩剖面的粘粒含量大于灰岩，说明白云岩剖面具有更高的风化强度。（5）越南北部气候环境对红土化作用有重要影响研究表明，越南不同剖面的红土化程度与气候背景是相匹配的，气候炎热少雨的河谷型地形，剖面中有机碳含量较低，而温湿高原环境植被旺盛，土壤有机碳较高，例如CD、CS、CT、SC等剖面的降雨量大、年平均气温高、水热配套好，红土化高，而TG、NO、LL和LC剖面位于干热河谷，气候炎热少雨，红土化程度低。（6）联合使用14C测年、Rb/Sr、δ13C和δ15N等技术，可以反演红土剖面的古环境特征利用AMS14C测年技术，测定出越南北部中有机碳的沉积年龄。结果显示剖面从全新世早起到全新世晚期，跨度约为5000a，其形成速率为3.8cm/a，其中TG坡面的沉积速率较快，约为4.6cm/a，SC剖面成土速率约为2.9cm/a。通过Rb/Sr、δ13C和δ15N值随深度的变化分析，发现越南北部剖面的古气候环境在更新世晚期到全新世中期，气候整体上是由暖湿向温干的方向发展，并且气候变化与这一地区海进和海退的变化相一致。本研究对热带岩溶地区红土地球化学发育规律的几点认识，有助于全面认识碳酸盐岩红土风化壳的成因机制问题，加深气候变化过程及红土演化规律及红色风化壳元素的地球化学迁移转化规律的认识，对于丰富岩溶红土的理论研究，探究红土成因机制及其影响因素具有重要意义。

The red weathering crust records important information such as paleoenvironment and paleoclimate change since the formation of laterite, which is of great significance to the study of global climate change. The study of geochemical process and evolution characteristics of carbonate weathering-forming land is an important part of element geochemical cycle in karst environment and the basis for the study of supergene resources and environment. At present, there are still several problems in the study of red weathering crust over carbonate rocks: (1) the formation mechanism of red weathering crust is still controversial; (2) most of the studies are concentrated in subtropical and temperate zones, but less in tropical zones where red weathering crust is strongly developed; (3) the relationship between geochemical processes of laterite elements and climate change needs to be improved; (4) the study of the relationship between red weathering crust and climate change needs to be improved. The comparative study of red weathering crust over dolomite and limestone lacks systematic data.In order to reveal the relationship between the material source, geochemical characteristics and climatic environment of carbonate overlying laterite in tropical areas, 12 laterite profiles developed on carbonate rocks were selected in northern Vietnam, and the genetic mechanism of laterite overlying carbonate rocks in northern Vietnam was discussed by means of field macro-evidence, soil physical and chemical properties and element geochemistry, a process model of carbonate soil formation is established. Then, the geochemical evolution law of laterite profile is revealed by using the element migration and activation characteristics, lateritization information and Sr isotope evidence of two typical dolomite and limestone profiles. Secondly, the two typical dolomite and limestone profiles are compared in terms of weathering degree, element content and grain size distribution, and differentiation characteristics, evolution process and controlling factors between the two profiles are analyzed. Finally, the environmental factors in the formation and evolution of laterite are clarified through the study of burnout and geochemistry of rare earth elements, and the geochemical differentiation and enrichment of elements in profile, the genesis mechanism of laterite and their relationship with climate and environment are discussed. Paleoclimate change from Pleistocene to mid-Holocene in northern Vietnam are reconstructed by Rb/Sr ratio, δ13C, δ15N and 14C. The main findings of this study are as follows:(1) Laterite over carbonate rocks in northern Vietnam mainly comes from underlying bedrock and is the product of in-situ weathering of carbonate rocks.From the macroscopic evidence, the structure of laterite overlying carbonate rocks in northern Vietnam is clear and stratified, which retains the residual structural characteristics of the original bedrock. From the geochemical criteria of major elements and trace elements, the profile without foreign components is the reflection of in-situ weathering profile characteristics. From the grain size distribution curve, the laterite profile shows coarse-grained peaks and fine-grained which means the of inheritance of original rocks and positive evolution of weathering. Mineral composition from dolomite and calcite in bedrock to illite and plagioclase at rock-soil interface to kaolinite, montmorillonite, chlorite and gibbsite in laterite shows the continuity of material sources.(2) Dolomite and limestone weathered laterite have the same profile characteristics, but their interface structure, weathering intensity and mineral composition are different.Firstly, in the process of weathering and evolution of dolomite and limestone in northern Vietnam, the volume of dolomite and limestone varies enormously. For each 1 m thick layer of soil, about 50 m of dolomite and 100 m of limestone are needed respectively. Secondly, influenced by the development of karst fissures, the front edges of weathering process of the two bedrocks are uneven, and the laterite profiles well preserve the microbedding structure of the bedrock. Thirdly, both minerals are the process of gradual transformation from soluble carbonate to insoluble silicate clay minerals. But there are also obvious differences between the two sections, which are shown as follows: the rock-soil interface of dolomite is easy to form rock fragmentation zone and rock powder layer, while the limestone mostly forms a dark brown chocolate layer (eluvial deposit layer) at the rock-soil interface, and a small amount of limestone powder layer occurs in the limestone section with dolomite and pore development, and the weathering strength of dolomite red soil is usually stronger than that of limestone.(3) Compared with processes of laterite from silicate rocks and carbonate rocks in subtropical China, weathering and soil formation of carbonate rocks in northern Vietnam has a special evolution law.The geochemical evolution of iron, aluminium and silicon in Vietnamese carbonate rocks can be divided into three stages: silicon-rich decalcification magnesium stage, aluminium-rich desilication stage and deep lateritization stage. From bedrock to upper soil layer, Al2O3 and Fe2O3 gradually increase, CaO and MgO decrease sharply, SiO2 increases sharply from rock to soil, and then decreases continuously. The change of trace elements shows three trends: fluctuation, slight decrease and stable change, which corresponds to the process of stable, deficit and enrichment of elements migration. From bedrock to rock-soil interface to soil layer, the degree of weathering is continuously strengthened, and its intensity is higher than that of laterite developed under subtropical humid climate in China. The 87Sr/86Sr ratio gradually decreases with depth increasing, which is controlled by the leaching of calcium-bearing minerals (such as kaolin) and potassium-bearing minerals (such as illite) in the profile.(4) The weathering profiles of dolomite and limestone in northern Vietnam have obvious geochemical differentiation characteristics.Dolomite lateritization desilication is weaker than limestone weathering profile, and its enrichment of aluminium is stronger than limestone. Dolomite projection points on triangle A-CN-K are mostly above illite, indicating that they have undergone intense weathering, while limestone weathering profile projection points are mostly below illite or close to illite, indicating that limestone weathering has not reached the stage of strong aluminium enrichment. Because the average content of dolomite in the dolomite rock in northern Vietnam is about 22%, its porosity develops rapidly and its dissolution ability is strong. In addition, the average content of acid insoluble matter in dolomite is 4.36%, while that in limestone is 1.78%, which is the reason why the thickness of dolomite is higher than that of limestone. In terms of clay content, the clay content of dolomite profile is higher than that of limestone, which indicates that dolomite profile has higher weathering intensity.(5) The climate environment in northern Vietnam have important influence on lateritization.The results show that the degree of lateritization of different profiles in Vietnam is matched with the climatic background. The Valley-type topography with hot climate and little rain has low organic carbon content in the profiles, while the warm and humid plateau environment is rich in vegetation and high in soil organic carbon.. For example, the profiles of CD, CS, CT and SC have high rainfall, high annual average temperature, good hydrothermal matching and the degree of lateritization is high, while the profiles of TG, NO, LL and LC profiles are located in the dry and hot valleys, the climate is hot and rainless, and the degree of lateritization is low.(6) Combining 14C dating, Rb/Sr, δ13C and δ15N techniques, the palaeoenvironmental characteristics of laterite profiles can be retrieved.The age of organic carbon deposition in northern Vietnam was determined by AMS 14C dating technique. The results show that the profile spans about 5000a from early Holocene to late Holocene, and its formation rate is 3.8cm/a. The deposition rate of TG slope is faster, about 4.6cm/a, and that of SC profile is about 2.9cm/a. By analyzing the variation of Rb/Sr, δ13C and δ15N values with depth, we found that the climate is developing from warm and wet to warm and dry on the whole, and the climate change is consistent with the transgression and regression from late Pleistocene to mid Holocene in northern Vietnam.This study is helpful to understand the genetic mechanism of laterite weathering crust in carbonate rocks, to deepen the understanding of climate change process, laterite evolution and geochemical migration and transformation of red weathering crust elements, to enrich the theoretical research of karst laterite. It is of great significance to explore the genetic mechanism of laterite and its influencing factors.