Parasite findings in archeological remains: Diagnosis and interpretation

Paleoparasitology has contributed to resolving the debate about the peopling of the Americas and determining the antiquity of human parasite infection. Hookworm (Ancylostomidae) and whipworm (Trichuris trichiura) and other exclusive human intestinal parasites have been recorded in pre-Columbian America. These parasite species originated in pre-hominids and have accompanied humans across continents when people went out of Africa. However, for those human populations that crossed the Bering Land Bridge from Siberia to Alaska, cold climate conditions hampered parasite transmission. Alternative migration routes have been proposed to explain the presence of these parasites in pre-Columbian populations in the Americas. Other parasites were established in the New World long before humans entered the American continents.One such malady is Chagas disease. Chagas disease, caused by Trypanosoma cruzi, offers an example of how animals and humans have interacted in the past. Classical theory points to the origin and dispersion of human T. cruzi infection among Andean populations, starting with sedentary habits and animal domestication 6000 years ago. However, recent PCR results in mummified bodies outside the Andean region have challenged this theory. Pre-Columbian Brazilian mummies were found positive for T. cruzi infection, raising an alternative hypothesis on the antiquity of Chagas disease in the Americas. Paleoparasitology is a new tool to study past events, shedding light on human and other animal behavior, migration routes, diet, and other aspects of host–parasite environment evolution.     

浙江省中岙细碧岩类岩石学岩石化学特征及其成因

前人长期将中岙金矿体的围岩误定为陆相安山岩、蚀变安山岩、安山玢岩、熔结凝灰岩等。1982年至今我们在野外和室内对中岙金矿床的地层和岩石进行了系统地岩石学、岩石化学研究,对这套以细碧岩类为主体的古火山岩系进行了重新命名和分层。并提出了细碧岩的成因。我们认为这可能有利于阐明金矿脉的成因和找矿方向。     

Isotopic constraints on Columbia River flood basalt genesis and the nature of the subcontinental mantle

Pb, O, Nd, and Sr isotopic data for the Columbia River basalts paint a complex picture for the origin of this flood basalt province. At least 3 distinct mantle sources appear to have been involved, superimposed upon which are the effects of crystal fractionation and mass exchange with evolved crustal wallrocks. To a large degree, the initiation of Columbia River volcanism and the geochemical characteristics of the basalts appear to have been influenced by subduction of the Juan de Fuca plate beneath the North American plate in a manner analogous to the origin of back-arc basins. The physical structure of the crust appears to have influenced the late stage evolution of the magmas by directing the locus of eruption to the border between the ancient continental interior and much younger crust to the south and west. This proximity to the continental interior also allowed old enriched subcontinental mantle to become involved in the very late stages of Columbia River volcanism. An important consequence of the existence of enriched mantle regions beneath continents is that the combination, crust plus enriched mantle, requires more incompatible elements to have been extracted from the remainder of the mantle than would be the case if no enriched mantle existed.     

Origin of silicic volcanism in the Panamanian arc: evidence for a two-stage fractionation process at El Valle volcano

In the Central American Volcanic Arc, adakite-like volcanism has often been described as volumetrically insignificant. However, extensive silicic adakitic volcanism does occur in the Panamanian arc and provides an opportunity to evaluate the origin of this magma-type as well as to contrast its origin with other Central American silicic magmas. The Quaternary volcanic deposits of El Valle volcano are characterized by pronounced depletions in the heavy rare earth elements, low Y, high Sr, high Sr/Y, relatively high MgO, and low K₂O/Na₂O, when compared with other Quaternary Central American volcanics at similar SiO₂. These chemical features are also diagnostic of adakitic signatures. Our new ⁴⁰Ar/³⁹Ar ages of lava flows and ash flows that compose the volcanic edifice of El Valle volcano illustrate that the eruptive volume of adakitic-like volcanism is substantial during the Quaternary (~120 km³). Adakitic-like magmas dominate the stratigraphic record. Common to all models for the origin of an adakite geochemical signature is the involvement of garnet, as a residual or fractionating phase. The stability of garnet in hydrous magmas has been recently reevaluated with important consequences; garnet is a stable primary igneous phase at pressure and temperature conditions expected for magma differentiation at the roots of a mature island arc. Moreover, adakite-like volcanism erupted at El Valle volcano displays the middle rare earth element depletion observed in other Panamanian volcanic centers that has been attributed to significant amphibole fractionation. Extensive amphibole fractionation may have occurred in two stages. The first stage of fractionation, garnet + amphibole fractionation, occurs from hydrous basaltic–andesitic parental magmas that have ponded at the base of an overthickened crust. The second stage occurs at mid-lower crustal levels where abundant amphibole + plagioclase and minor sphene crystallized from water-rich magmas. These two stages combined may have resulted in an amphibole-rich cumulate layer. This amphibole layer is likely the source of the abundant amphibole-rich cumulate enclaves and blobs found in volcanic products across the Panamanian arc. Stalling of water-rich magmas during this two-stage fractionation process could drive the interstitial liquids to the evolved compositions typical of continental crust, while leaving behind amphibole-rich cumulate rocks that may eventually be returned to the asthenosphere. Differentiation of H₂O-rich magmas under the conditions appropriate for the roots of island arcs may therefore be a key process in developing a better understanding of the generation of continental crust in island arc environments.     

海水环境下巴氏芽孢杆菌驯化及钙质砂固化效果研究

为了提升微生物诱导碳酸盐沉淀(MICP)技术在海洋环境下对钙质砂的加固效果,在以往研究的基础上,设计进行了人工海水环境下巴氏芽孢杆菌多梯度人工驯化培养试验,并结合MICP固化钙质砂柱的力学试验和微细观结构分析,对巴氏芽孢杆菌的驯化效果进行了综合评价。结果表明:(1)海水环境下五梯度驯化后细菌的菌液浓度可达到淡水环境的97%以上,其与胶结液作用后碳酸盐的生成量较淡水环境下有一定幅度提高;(2)驯化后的巴氏芽孢杆菌具有很好的温度适应能力,在10～30℃温度下均有较好的MICP性能;(3)海水环境下加固的钙质砂柱无论是碳酸盐生成量还是无侧限抗压强度均较未驯化前高,尤其是五梯度驯化后的细菌,驯化后的细菌菌体变小,在海水环境生成的碳酸盐(碳酸钙和碳酸镁)晶体更小,更加致密,能更好地填充钙质砂颗粒的孔隙并胶结相邻的钙质砂颗粒,具有更优异的MICP性能。相关研究思路和方法可为MICP技术在海洋环境钙质砂地基加固方面的研究与应用提供参考。     

用于构建生物系统发育树的古DNA序列

主要综述了古 DNA研究进展以及结合古 DNA序列和基因库中的数据构建系统发育树。这些研究能解决许多有关演化生物学、考古学、人类演化及迁移、动植物的家养和驯化过程及早期农业的发展、考古点的动植物残骸的精确鉴定及地质演化等问题。另外 ,还列举了一些重要的实例     

The occurrence of bothriodontines (Artiodactyla, Mammalia) in the Paleogene of Asia with special reference to Elomeryx: Paleobiogeographical implications

Anthracotheriid remains from several Paleogene localities of central and eastern Asia have been re-examined. Several fossil remains attributed to the genera Bothriodon, Brachyodus and Hyoboops can be referred to Elomeryx which extends the geographical distribution of the genus to the whole area of Asia. These results demonstrate the role that Asia played in the biogeographical history of mammals and further support the proposed origin of North American Elomeryx from an Asian ancestor.     

A pyrolysis and stable isotopic approach to investigate the origin of methyltrimethyltridecylchromans (MTTCs)

Methyltrimethyltridecylchromans (MTTCs) have been widely detected in sediments and crude oils from various depositional settings and are established markers for palaeosalinities. A likely origin of these compounds, which show a distinctive isoprenoid substituted aromatic structure, seems to be condensation reactions of phytol with higher plant derived alkyl phenols during early diagenesis. However, a direct biological origin from phytoplanktonic organisms cannot be excluded. To further investigate the potential origin from condensation reactions, an online pyrolysis–gas chromatography–isotope ratio mass spectrometry (PY–GC–irMS) method with the capacity to measure δ¹³C in fragments (trimethylphenol and pristenes) generated from 5,7,8-trimethyl-MTTC was developed in this study. This straight forward technique poses a great potential for the elucidation of chroman formation in geological samples as it possibly enables the distinction between the different proposed sources of isoprenoid and alkyl-phenol fragments (mainly phytoplankton and higher plants, respectively) based on their stable isotopic compositions. Furthermore, it might be useful for the investigation of products generated from MTTCs during thermal maturation of geological samples.     

Beyond Subduction and Plumes: A Unified Tectonic-Petrogenetic Model for the Mexican Volcanic Belt

The Mexican Volcanic Belt (MVB) is a major linear belt of Miocene to present-day volcanism in southern Mexico. Its origin has been controversial, although the majority opinion views it as a volcanic arc related to the subduction of the Cocos plate under the North American plate. Both calc-alkaline and alkaline volcanism characterize the belt; the latter has been previously cited as indicative of the role of a mantle plume. Here we present objections to these explanations, and conclude on the basis of geological, geochemical, and geophysical data that the MVB is unrelated to subduction or to a mantle plume, and is instead a rift-like structure experiencing active extension. Calc-alkaline or alkaline geochemistry of magmas is not useful for inferring tectonic setting, but reflects source parameters and petrogenetic processes. For the MVB, calc-alkaline geochemistry suggests crustal contamination, and the OIB-like geochemistry suggests an enriched mantle source. Our proposal of a heterogeneous mantle beneath the MVB comprising “normal” mantle and metasomatic, enriched veins, can explain the close association in space and time of calc-alkaline and alkaline volcanism throughout the belt.     

广西地区晚更新世野猪对家猪的遗传贡献

家猪是由居住在世界不同地区的人类对野猪的长期驯化而来,考古学研究表明近东和中国可能是家猪的驯养中心.为了寻找野猪对家猪驯化遗传贡献的分子证据,对采集于广西壮族自治区3个不同地点的30个晚更新世野猪化石样品开展了古DNA研究,从化石样品中获得了线粒体基因组的D-loop部分序列,结合现代家猪、野猪DNA同源序列信息,构建了Network网络结构图和系统发育树.结果表明广西古代野猪与欧洲猪科动物之间存在历史基因流,与亚洲家猪之间具有遗传的连续性,在家猪的驯化过程中有遗传贡献.研究结果从新的地域角度为家猪的多地区驯化起源提供了分子证据.      

煤层气储层的显微孔裂隙成因分类及其应用

采用煤岩学方法研究煤储层特性,可直接观察孔裂隙的分布、形态、数量、充填状态等特征,有利于查明显微孔裂隙成因、影响因素及演化规律。将显微孔隙分为生物成因孔和非生物成因孔;显微裂隙划分出内生裂隙、继承性裂隙、层面裂隙和构造裂隙;分别研究了各类显微孔裂隙在煤储层中的分布、随煤化作用的演化规律及其与渗透率的关系,并取得了良好的效果。      

A morphological, sedimentological and geophysical investigation of the Woore Moraine, Shropshire, England

The Bar Hill-Whitchurch-Wrexham Morainic Complex is a large-scale glacial landform thought to represent either the maximum extent or the re-advance of the British-Irish Ice Sheet during the Late Devensian. The origin of the moraine remains uncertain as its key characteristics have not been studied in detail due to a lack of exposures from which its large-scale structure can be determined. The development of new technologies has enabled detailed examination of the topography and internal structure of such large-scale landforms. This paper describes a multi-disciplinary approach involving digital geomorphological mapping using enhanced resolution NextMAP™ digital surface models, geophysical imaging (electrical resistivity tomography) and conventional sedimentological analyses. This combination of techniques is useful for elucidating the origin of a large glacial landform in a region of poor exposure. Digital elevation models such as NextMAP™ offer an efficient and accurate method for landform-mapping, whilst electrical resistivity tomography was able to map the major constituent sediments of the moraine, which had in turn been identified in the single exposure available. Additional geophysical techniques should however be applied to provide further structural data and thereby enable a more detailed interpretation of the moraine's internal structure. Preliminary findings indicate that the moraine is a glaciotectonic landform composed of diamicton and glaciofluvial sediments, an origin consistent with recent suggestions that the Cheshire Plain contained an active ice lobe during the last glacial maximum.     

Prehistoric Warfare in Central Arizona,USA: Assessing Its Scale with Ceramic Chemistry

The scale of warfare and alliance in the ancient American Southwest is hotly debated for the interval from A.D. 1100 to 1450. Some archaeologists posit conflict persistently waged in central Arizona, which thereby promoted the emergence of region‐sized polities, including the so‐called Verde Confederacy. Relying largely on settlement‐pattern data, these theorists have hypothesized warfare and alliance practiced at a regional scale, apparently larger than anywhere else in the prehistoric American Southwest. Other evidence, however, has challenged the Verde Confederacy model and the level at which hostilities raged in central Arizona. It calls into question the organizational capabilities of hostile tribal groups and their strategic goals. In this paper, we add a new line of complementary information based on the compositional analysis of phyllite‐tempered plain ware ceramics. By reconstructing the pottery's movement and exchange across the region, we outline patterns of interaction useful for evaluating the scale of alliance and warfare in central Arizona. We find, contrary to the expectations of regional scale alliances, that the ceramic exchange networks segregated some populations previously proposed to have been aligned, while integrating groups thought previously to have been enemies. The ceramic data indicate alliances and hostilities at a relatively local scale.     

Mammoths and mylodonts: Exotic species from two different continents in North American Pleistocene faunas

Throughout the Cenozoic, the North American mammalian fauna has been enriched by the appearance of new taxa originating on different continents. During most of the Tertiary, the primary source area of these new taxa was Eurasia with dispersal across some version of the Bering Land Bridge. In the late Pliocene (Blancan) ca. 2.5 mya, the creation of the Panamanian Land Bridge permitted the northward dispersal of species of South American origin including ground sloths. One of these sloths was “Glossotherium” chapadmalense, which in turn gave rise to the Pleistocene species Paramylodon harlani. Mammoths first appear in North America at the beginning of the Irvingtonian ca. 1.9 mya. Despite originating on two different continents, the two species are often found together in North American Pleistocene faunas and shared a common habitat. Both of these lineages are commonly interpreted as grazers, indicative of open grassland habitat, and both of these exotic species shared this habitat with North American endemic species such as horses, also interpreted as grazers. Despite their association in North American faunas, mammoths did not disperse into South America and mylodont sloths were unable to disperse into Eurasia. This suggests there were some aspects of their ecology they did not have in common and there existed a limited zone of conditions that permitted them to share common habitat. There is no evidence that the appearance of either species in North America resulted in the extinction of any native species. The question is how these different species, immigrants and endemics, were able to avoid competition, coexist, and become integrated into a single fauna, thus enriching the overall North American Pleistocene fauna.     

我国原生晕研究50年的主要成果

金属矿床原生晕研究表明,原生晕方法可指导矿区外围及区域成矿带上的矿点或异常分类评价,提高中大比例尺的矿产预测水平,为发现新矿床(体)提供依据。在矿床不同勘查阶段追踪盲矿体、确定矿体赋存部位。还可为研究矿质来源、控矿因素、围岩蚀变等提供地球化学证据和基础资料。文章阐述了原生晕五十年的研究历程、主要成果,以及今后发展的方向。     

东秦岭花岗岩的平均原子量及其与成岩成矿作用的关系

东秦岭不同构造单元中花岗岩类的平均原子量()有不同程度的差异。华北地台南缘为高值(20.65～21.15),秦岭褶皱系为中低值(20.35～20.43)。岩体的值与成岩物质来源和岩浆演化趋势有关,地台区花岗岩值介于“玄武岩地壳”平均值和“花岗岩地壳”平均值之间,而地槽区花岗岩则介于沉积壳层和花岗岩壳层之间。值东秦岭区域成矿作用分带与花岗岩的值分带有极明显的空间依存关系,成矿岩体的值远高于非成矿岩体,与金成矿作用有关岩体的值高于与铝多金属成矿作用有关的岩体。     

福建南平伟晶岩中的柱磷锶锂矿—磷铝钙锂石

柱磷锶锂矿与磷铝钙锂石是一完全类质同象系列（Ｓｒ，Ｃａ）的两个端元矿物，二者在自然界都十分罕见，仅少量产于花岗伟晶岩中，所报道的产地也廖廖无几。笔者于１９８５年在福建南平花岗伟晶岩田的白云母－钠长石－锂辉石型伟晶岩中发现了这两种矿物、二者在国内均属首次发现，本文详细地报道了南平柱磷锶锂矿－磷铝钙锂石的产状、物理性质、化学成分、Ｘ射线衍射特征及矿物晶胞参数等。研究指出：南平柱磷锶锂矿是伟晶岩中原生大     

Slope instability in Nicaragua triggered by Hurricane Mitch: distribution of shallow mass movements

The heavy rains associated with Hurricane Mitch triggered off a number of slope instability processes in several Central American countries. Different instability processes have been acknowledged for the various mountainous regions of Nicaragua. An enormous movement of the Casita Volcano slopes resulted in numerous deaths and some deep movements have been reactivated. On the other hand, numerous shallow mass movements and debris flows have given rise to great material loss throughout a large part of Nicaraguan mountains.Mapping the shallow mass movements in an area of Central Nicaragua clearly reveals the close ties between their distribution and some geomorphological factors. A susceptibility model has been constructed for shallow mass movements based on field mapping of the shallow mass movement distribution, the geomorphological map as well as the digital slope and accumulated flow models. A logistical regression analysis was applied. The study area has been categorized into three classes of relative landslide susceptibility. Given that phenomena of this nature occur much more frequently in the high susceptibility class, 94% of the shallow mass movements that have been used to test the model are in the high and medium susceptibility classes . The geological and geomorphological conditions of the study area are representative of a large sector of the central Nicaraguan region. Consequently, the methodology followed in this paper is deemed to constitute a useful tool, both regarding the design of new infrastructures, and as a guide to the urban development of the area.     

Sediment slump structures: a review of diagnostic criteria and application to an example from Newfoundland

In the study of the history of deformed sedimentary rocks it is important that the cause of the deformation and the timing of deformation relative to metamorphic and tectonic events be assessed. There is a continuous gradation between the deformation of freshly deposited sediments by gravitational forces and the deformation of well-lithified sediments by tectonic forces, so determining the degree to which gravity, tectonism and lithification influenced deformation can be very difficult. The characteristics that may be considered in determining the origin of deformational structures in sedimentary rocks can be divided into five categories: Ductile deformation structures (1) can provide definitive criteria for recognizing post-lithification deformation, but not pre-lithification deformation. This also holds for (2), brittle deformation structures and décollements. Overprinting of sediment reworking or remobilization structures (3) are the best criteria for recognizing pre-lithification structures. Fabrics (4) can be very useful but are as yet poorly understood, and there are misconceptions in the literature about what sort of fabrics are or are not found in unlithified sediments. Spatial relationships (5) may also tell us a great deal, but are most useful when taken in conjunction with other types of evidence.Complex fold patterns in sandstones on Farmer Head, north-central Newfoundland, provide a case study for criteria that may be used to determine the degree of lithification during deformation. Although these folds have been interpreted as slump folds by earlier workers, fabrics and spatial relationships point to a tectonic post-lithification origin for the structures, a conclusion which has significant implications for the interpretation of the regional geology.     

中国东部地带表土稀土元素的地球化学特征

对中国东部从黑龙江省到海南省的纵向大断面50个表土样品的稀土元素(REE)含量进行了测定,结果显示其平均含量高于中国土壤和世界土壤的平均值;其稀土元素组成特点表现为轻稀土(LREE)富集,重稀土(HREE)亏损,Eu的负异常和Ce的正异常;未发现稀土元素总量∑REE和轻重稀土比值∑LREE/∑HREE随纬度或年均温度、年降水量有明显的地带性规律变化;δCe值的分布特征显示在气候达到南亚热带-北热带地区的湿热程度及风化强度时,表土才会出现显著的Ce正异常;在Ce/Eu对Eu/Sm图解上不同母岩类型的表土参数差异明显,尤其是玄武岩发育的表土与中酸性岩石和沉积岩发育的表土之间具有明显差异。本研究表明,中国东部表土的稀土元素分布特征没有明确的气候带示踪意义,而主要具有成土母质类型示踪意义;δCe值的显著正异常可以示踪南亚热带-热带气候;由于影响因素复杂,各种特征参数的细微变化对沉积物成因、物源区以及区域气候的指示意义尚待积累更多的数据并参考其他环境指标才能做出正确判断。