贵州碳酸盐岩风化壳形成地球化学过程、对比及年代学研究Geochemical Processes, Comparison and Dating for the Weathering Crusts in Karst Regions of Guizhou Province

由于缺乏相应的沉积地层，贵州新生代地质、环境演化恢复一直是学术界的难点问题。夷平面研究的兴起，为陆地地壳抬升、地貌演变等反演提供了理论基础，而风化壳正是夷平面研究的重要替代对象，尤其是对各类沉积地层不发育的地区。因而，贵州高原各级台地上发育有较为广泛的红色风化壳自然地、就成了主要研究载体。然而一与其它岩类不同，碳酸盐岩风化成土作用过程研究并没有得到同等重视，其研究范围和程度均很不充分。显然，要想利用碳酸盐岩风化壳进行夷平面等地质、地貌意义研究，就必需详细了解贵州或中国南方碳酸盐岩风化成土的基本过程。也只有如此，才能明确各种对比指标的使用条件和范围，才能明确各种测年结果的具体意义，才能真正地通过贵州碳酸盐岩风化壳获取全省地质、环境演化信息。本论文通过对贵州省岩溶台地碳酸盐岩石灰土、红色风化壳剖面形成地球化学过程的剖析，开展石灰土与红色风化壳之间的关联和差异性综合对比、红色风化壳之间发育程度的比较，以及风化壳剖面尝试性的侧年等方面研究，取得了以下儿点认识：1、石灰土形成地球化学过程及对比通过矿物组成、粒度分布特征、地球化学方法判别，确定了本文所选石灰土剖面物质来源于下伏碳酸盐岩中的酸不溶物，是碳酸盐岩风化后酸不溶物原地残余堆积的结果。石灰土形成的地球化学过程都遵循碳酸盐岩风化成土之两阶段模式：母岩－酸不溶物，大量可溶性物质Ca、Mg、Mn、P、Na淋失，而Si、K·Fe、Al、Ti则相对富集。该过程的矿物组成变化表现为，伴随碳酸盐矿物（方解石、白云石等）的溶解、迁移，硅酸盐相矿物（长石、2:1型粘土矿物等）残余、累积。酸不溶物，土层或土层的演化，K、Si（长石、伊利石）不断淋失，而Al（伊利石、高岭石、三水铝石）、Fe（针铁矿、赤铁矿等）逐渐富集，体现出脱硅、富铝（铁）过程。我们强调碳酸盐岩风化成土分为两个阶段，但也认识到风化作用是综合的、复杂的：在碳酸盐矿物大量淋失过程中，同时也进行着酸不溶物的风化。石灰土分为原生和次生两种成因类型。原生石灰土的风化程度总体较低，剖面中还残留一定量的CaCO3，剖面从下到上矿物组成、地球化学各种指标具有逐渐演化的过渡特征。原生石灰上土层演化过程显示出正风化序列，从下到上风化程度逐渐增大、可溶性物质逐渐减少、稳定和相对稳定组分（Al、Fe．、REE）含量不断增大。另外，主量元素的质量迁移系数在剖面中的变化与风化程度呈明显的相关性。而次生石灰土不但具有很高的风化程度，而且剖面无过渡特征，显示可能是由遭受强烈风化作用的物质直接转变形成的。剖面中也含有一定量后期加入的碳酸盐，但与高CIA值特征不相匹配；SiO2、Al2O3、Fe2O3组分具有不同的变化特征，与）成化程度无明显关联；REE在剖面岩一上界面出现富集层。2、碳酸盐岩红色风化壳形成地球化学过程及其与石灰土的对比红色风化壳形成的地球化学过程也遵循碳酸盐岩风化成土之两阶段模式：母岩一酸不溶物，大量可溶性物质Ca、Mg、Mn、P、Na淋失，而Si、K、Fe、Al、Ti则相对富集。该过程的矿物组成变化表现为，伴随碳酸盐矿物（方解石、白云石等）的溶解、迁移，硅酸盆相矿物（长石、2:1型粘土矿物等）残余、累积。酸不济物一土层或上层的演化，K、Si（长石、伊利石）不断淋失，而Al（伊利石、高岭石、三水铝石）、Fe（针铁矿、赤铁矿等）逐渐富集，体现出脱硅、富铝（铁）过程。石灰土与红色风化壳之间既存在共性，又有一定的差异性。红色风化壳与原生石灰土一样都具有过渡特征，但后者仅在剖面下部出现一定的过渡层位；原生石灰士的城化程度远低于红色风化壳，仅与后者底部土层相当；原生石灰土不具有红色风化壳之岩-土REE（超常）富集层。总体上，原生石灰土可以作为红色风化壳的前身。次生石灰土与红色风化壳在矿物组成、风化程度等各种地球化学指标等都十分接近（略低），显示与红色风化壳之间存在某种关联：由红色风化壳物质直接转变，或由酸不溶物已强烈风化的（白云岩）岩粉、碎裂岩风化形成。3、碳酸盐岩风化成土母岩差异性碳酸盐岩风化成土存在母岩差异性，石灰土母岩差异性较为明显，而红色风化壳的母岩差异性较弱，体现出红色风化壳的均一化特征。石灰土母岩差异性体现为：母岩为灰岩的石灰土剖面主量元素含量变化特征较为一致，而白云岩则具有不同的变化；灰岩石灰土Fe3＋、Al具有不同的富集、亏损特征，且具有富集层的补偿亏损层，而白云岩石灰上两组分都呈现无补偿层位的相同富集态势；灰岩石灰土剖面出现负Eu异常和具以Gd为中心的倒“V”型MREE稀土富集特征（母岩标准化），而白云岩石灰土无明显Eu异常和具L既E或HREE稀士．富集特征；灰岩和白云岩石灰土的微量元素富集、亏损特征也有所不同，前者从上到下逐渐富集，而后者无明显变化趋势。红色风化壳形成的基本过程、主量元素地球化学行为无明显的母岩相关性，没有如石灰土剖面灰岩和白云岩之间存在的差异性，显示出红土化作用的均一化过程；微量元素中受重矿物影响的元素与母岩类型有一定的关联，但大多数元素的亏损、富集等与具体剖面的微环境关系密切。4、碳酸盐岩红色风化壳发育程度的对比及意义多利指标对比显示所选红色风化壳的风化程度有一定的强弱差别：平坝剖面＞湖潮剖面＞天龙剖面、大兴剖面＞花溪剖面、新蒲剖面，但这种差异性不足以否定各剖面隶属于贵州山盆期广泛夷平面的基本推测。各剖面之间的微弱差异是红色风化壳形成时纬度分带和垂向分带的体现。低纬度的平坝、湖潮、天龙剖面经历的风化作用强于高纬度的新蒲、大兴剖面；高海拔的新蒲剖面风化程度低于海拔低的大兴剖面。5、红色风化壳次生石英裂变径迹测年红色风化壳次生石英裂变径迹方法测年尝试，得到一定的结果和认识：晶形相对较好的石英，是次生的，与母岩中碎屑及成岩阶段没有关联；各剖面上部与中、下部次生石英的诱发裂变径迹的密度有着明显的区别，可能暗示它们的形成环境不同；名一剖面石英的形成或退火年龄分布较为分散，1.2-25.2Ma，同一剖面的石英年龄也不均一，变化较大；从下到上，年龄值呈现出逐渐减小的规律性，与风化作用的正常序列相反。如果能确切其成因，次生石英裂变径迹年代学研究将是确定风化壳形成时代及揭示主要风化作用信，却钩有利武器。

The ADH1B Arg47His polymorphism in East Asian populations and expansion of rice domestication in history

Background: The emergence of agriculture about 10,000 years ago marks a dramatic change in human evolutionary history. The diet shift in agriculture societies might have a great impact on the genetic makeup of Neolithic human populations. The regionally restricted enrichment of the class I alcohol dehydrogenase sequence polymorphism (ADH1BArg47His) in southern China and the adjacent areas suggests Darwinian positive selection on this genetic locus during Neolithic time though the driving force is yet to be disclosed. Results: We studied a total of 38 populations (2,275 individuals) including Han Chinese, Tibetan and other ethnic populations across China. The geographic distribution of the ADH1B*47His allele in these populations indicates a clear east-to-west cline, and it is dominant in south-eastern populations but rare in Tibetan populations. The molecular dating suggests that the emergence of the ADH1B*47His allele occurred about 10,000 similar to 7,000 years ago. Conclusion: We present genetic evidence of selection on the ADH1BArg47His polymorphism caused by the emergence and expansion of rice domestication in East Asia. The geographic distribution of the ADH1B*47His allele in East Asia is consistent with the unearthed culture relic sites of rice domestication in China. The estimated origin time of ADH1B*47His allele in those populations coincides with the time of origin and expansion of Neolithic agriculture in southern China.

Phylogenetic study of complete cytochrome b genes in musk deer (genus Moschus) using museum samples

As an endangered animal group, musk deer (genus Moschus) are not only a great concern of wildlife conservation, but also of special interest to evolutionary studies due to long-standing arguments on the taxonomic and phylogenetic associations in this group. Using museum samples, we sequenced complete mitochondrial cytochrome b genes (1140 bp) of all suggested species of musk deer in order to reconstruct their phylogenetic history through molecular information. Our results showed that the cytochrome b gene tree is rather robust and concurred for all the algorithms employed (parsimony, maximum likelihood, and distance methods). Further, the relative rate test indicated a constant sequence substitution rate among all the species, permitting the dating of divergence events by molecular clock. According to the molecular topology, M. moschiferus branched off the earliest from a common ancestor of musk deer (about 700,000 years ago); then followed the bifurcation forming the M. berezouskii lineage and the lineage clustering M. fuscus, M. chrysogaster, and M. leucogaster (around 370,000 years before present), interestingly the most recent speciation event in musk deer happened rather recently (140,000 years ago), which might have resulted from the diversified habitats and geographic barriers in southwest China caused by gigantic movements of the Qinghai-Tibetan Plateau in history. Combining the data of current distributions, fossil records, and molecular data of this study, we suggest that the historical dispersion of musk deer might be from north to south in China. Additionally, in our further analyses involving other pecora species, musk deer was strongly supported as a monophyletic group and a valid family in Artiodactyla, closely related to Cervidae. (C) 1999 Academic Press.

A multi-locus phylogeny of Nectogalini shrews and influences of the paleoclimate on speciation and evolution

Nectogaline shrews are a major component of the small mammalian fauna of Europe and Asia, and are notable for their diverse ecology, including utilization of aquatic habitats. So far, molecular phylogenetic analyses including nectogaline species have been unable to infer a well-resolved, well-supported phylogeny, thus limiting the power of comparative evolutionary and ecological analyses of the group. Here, we employ Bayesian phylogenetic analyses of eight mitochondrial and three nuclear genes to infer the phylogenetic relationships of nectogaline shrews. We subsequently use this phylogeny to assess the genetic diversity within the genus Episoriculus, and determine whether adaptation to aquatic habitats evolved independently multiple times. Moreover, we both analyze the fossil record and employ Bayesian relaxed clock divergence dating analyses of DNA to assess the impact of historical global climate change on the biogeography of Nectogalini. We infer strong support for the polyphyly of the genus Episoriculus. We also find strong evidence that the ability to heavily utilize aquatic habitats evolved independently in both Neomys and Chimarrogale + Nectogale lineages. Our Bayesian molecular divergence analysis suggests that the early history of Nectogalini is characterized by a rapid radiation at the Miocene/Pliocene boundary, thus potentially explaining the lack of resolution at the base of the tree. Finally, we find evidence that nectogalines once inhabited northern latitudes, but the global cooling and desiccating events at the Miocene/Pliocene and Pliocene/Pleistocene boundaries and Pleistocene glaciation resulted in the migration of most Nectogalini lineages to their present day southern distribution. (C) 2010 Elsevier Inc. All rights reserved.

Genetic relationship of Chinese and Japanese gamecocks revealed by mtDNA sequence variation

Cockfighting has a very long history dating back to as early as 2500 years ago in China. Cockfighting was intertwined with human cultural traditions, helped disperse chickens across the world, and influenced the subsequent breed selection. Therefore, trac

Sedimentary records of water environment in lake Chaohu in the Yangtze delta region, China

Three lacustrine core samples were collected from Chaohu lake in December 2002 in the Yangtze delta region. The grain sizes were analyzed using a Laser Analyzer to obtain grain-size parameters. Sediment geochronology was determined in radioisotopes Cs-137 and the average sedimentary rates are 0.29cm.a(-1), 0.35 cm.a(-1) and 0.24cm-a(-1) in Cores C 1, C2 and C3, respectively. The grain-size parameters of the deposits vary regularly with the fluctuation of hydrodynamics. From 1950s to the beginning of 20th century, coarse-grained sediment was deposited, suggesting strong hydraulic conditions and high water-level periods with much precipitation; from the start of 20(th) century to latter half of 18(th) century, fine-grained sediment was deposited, indicating that weak hydraulic conditions and low water-level periods with less precipitation; before the first half of 18(th) century, coarse-grained sediment was deposited, suggesting great velocity of flow and high water-level periods of more precipitation.