29 resultados para Pre-Mesozoic basement of Iberia
Resumo:
现代人起源和史前迁移问题的遗传学研究是一个受到广泛关注的研究领 域。首先,它可以解答人类所关心的关于自身的起源以及我们祖先的史前活动问 题;其次,现代人祖先分开并扩散到世界各地,由于受到不同的外界环境和不同 的历史事件的影响,遗传上发生相应的变化,形成现有人群之间不仅在外表上存 在差异,同时在对疾病的易感性方面也存在差异。近年来的研究还发现,不同人 群之间在对药物的反应上也存在差异。 因此,人群起源与史前迁移研究对生物 医学研究也至关重要。目前,世界各地人群的起源和史前迁移问题的研究已经取 得很多进展,东亚之外的其它各个地区现有人群的起源和迁移已经相当清楚,东 亚现代人的起源对完整回答现代人的起源问题至关重要。 东亚现代人史前早期迁移的问题还存在很大争议,对现有研究结果的解释 甚至存在冲突。通过对东亚地区现有人群展开系统采样,并对东亚特有的Y 单 倍型遗传标记进行扫描,以东亚现代人特有的单倍型组O3-M122 下的各个特征 位点为遗传标记,我们对来自东亚地区的2332 份男性样本进行了研究。结果发 现,O3-M122 单倍型组为东亚现代人群的主导单倍型,其平均频率是44.3%。 以SNPs 突变特征为背景,展开SNPs-STRs 相结合的研究,通过大量的分析和统 计检验,从STRs 数据上可以看出东亚现代人南部人群的O3-M122 单倍型组的 多样性比北方人群高。这一证据揭示出东亚现代人特有单倍型O3-M122 突变为 东亚南部起源,然后随着东亚现代人早期的由南向北迁移活动而扩散到北方。利 用SNPs-STRs 相结合的遗传学分析手段,推导出东亚特有单倍型组O3-M122 伴 随人群由南向北的早期迁移事件发生于距今约25000~30000 年以前,这一结论 与东亚现代人的化石证据推断的结论相一致。O3-M122 单倍型组的史前早期迁 移事件有助于从遗传学角度透视东亚现代人早期迁移的路线和起源问题。 东亚地区现代人史前迁移活动遗留下神秘的悬棺文化一直令人费解,考古学的推论存在很大争议。我们利用遗传学手段对现存悬棺文化的保留人群展开研 究,采用父系和母系遗传标记相结合的方法探讨悬棺文化的传播人群的族源。从 遗传上看,悬棺葬俗的拥有人群不论从母系还是父系遗传学证据都为典型的东亚 南方人群。 为最终解决东亚现代人起源和史前迁移问题,我们对考古发掘出来的东亚 地区现代人化石展开古DNA(ancient DNA, aDNA)研究。目前,aDNA 分析的 技术和手段已经建立并逐步成熟,并且积累了一定量的东亚现代人的aDNA 数 据,这一研究还在继续。aDNA 最终会为解答东亚现代人起源和史前迁移问题提 供强有力的遗传学证据。
Resumo:
胚胎移植具有加速家畜良种推广的潜力。胚胎移植能直接引入纯种动物,并且能避免直接进口动物时可能会带来一些较大传染病(例如口蹄疫)的风险,因此具有成本低、安全性高、直接引入良种的特点。但是胚胎移植的成功率可能会受到很多因素的影响。这些因素可归纳为三个方面:胚胎因素;胚胎和受体的相互作用;受体因素。另一方面,胚胎移植目的是为了获得优秀生产性能的良种个体,但是出生的后代的生长发育情况也会和很多因素有关,例如出生大小、当地气候条件、饲养条件和胚胎移植季节等。因此,研究影响胚胎移植妊娠率以及出生后代生长发育的因素对胚胎移植在生产中的应用有重要意义。杜泊羊作为一种肉用绵羊,品种优良,经济价值很高,被认为应予以积极推广。用胚胎工程对杜泊羊进行推广可能是一个较好的办法。绵羊胚胎工程近年来已经取得了较大进展,例如超数排卵、体外胚胎生产、胚胎冷冻和胚胎移植的研究都取得了一系列的成果。在影响绵羊胚胎移植效果的具体因素中,已有一些关于不同胚胎移植数目、胚龄、冻胚和鲜胚、胚胎移植方法等报道,但是受体品种对杜泊羊的胚胎移植的研究还未见报道,季节对杜泊羊胚胎移植的影响的研究结果也不一致。因此本实验应用质量稳定的胚胎,采用单胚移植,以移植的妊娠率为指标,研究了受体品种和季节因素对杜泊羊冷冻胚胎移植成功率影响,结果发现在三个不同品种的受体中,胚胎移植妊娠率无显著差异(P>0.05);但是季节对胚胎移植成功率有显著影响,秋季移植妊娠率(68.6%)显著高于春季(58.5%,P<0.05)。在山羊等其他动物的研究中表明,受体情况不影响胚胎移植出生的后代的生长发育。本实验以羔羊的出生重、1个月体重和断乳时(2个月时)体重为指标,分析了受体体重和季节对胚胎移植出生杜泊羊羔羊的早期生长发育的影响,结果表明,不同体重的受体会影响羔羊的出生重(P<0.05),即体重较大的受体出生的羔羊的体重也较大,但经过两个月的哺乳期生长后,羔羊的生长发育情况已无明显差异(P>0.05)。有研究表明羔羊早期的生长发育情况和外界条件有关。不同季节进行胚胎移植,羔羊出生时间也不同。因此,实验研究了不同季节对胚胎移植出生羔羊早期生长发育的影响。结果发现,季节显著影响了羔羊的生长发育,春季和秋季移植出生的羔羊在出生重方面差异不显著(P>0.05),但春季移植出生的羔羊的后来的生长情况要明显好于秋季(P<0.05)。
Resumo:
本论文首先介绍真空技术涉及的物理基础和真空获得的有关知识,然后讲述,了H_RFL(兰州重离子加速器研究装置)真空系统的基本概况,在此基础上阐述了本论文主要的两部分:H_RFL前束线真空系统的改造;新型H_RFL佩800低温泵的设计一及热负荷的计算。其中H工RF[前束线真空系统的改造已经于2001年9月份完成并为兰州重离子加速器的正常运行提供了必要的真空条件。新型111佩又FL佩800低温泵正在加工生产中,并将用于大型超高真空系统H工R凡厂SSC(兰州重离子加速器研究装置主加速器)的抽空。H工RFL前束线真空系统的改造介绍了兰州重离子加速器前束线真空系统的基本结构,详细说明了H工RFL前束线真空系统改造前的流导、气体负荷及压力分布情况。提出了具体的改造措施。真空系统达到了预计要求:泵口压强小于5只10-6Pa,两泵之间束运管道中心平面压强小于1x10-5Pa.结果表明H工RFL前束线真空系统的改造方案是有效的。新型HIRFL一800低温泵的设计及热负荷的计算介绍了近代物理研究所自行研制的新型H工RFL一800低温泵。对其抽速,低温冷凝板和屏蔽板的热负荷进行了具体的分析和计算。肯定了新型H工RFL佩800低温泵的设计方案。
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为黄土丘陵区生态安全预警及其建设提供科学依据。【方法】以纸坊沟流域近70年代表年份生态安全态势及影响因子的分析为基础,参考压力-状态-响应(PSR)模型建立农业生态安全预警指标体系。运用层次分析法(AHP)和德尔菲法(Delphi)确定指标权重,采用综合指数法计算生态安全质量值,用演化轴解释生态安全预警模式,定量评价该流域1938~2005年的农业生态安全状况,并预测2015年的发展趋势。【结果】纸坊沟流域1938年处于蓝灯区,无需预警;1958年为黑灯区,需作生态安全恶化速度预警;1975和1985年处于红灯区,需作生态安全较差状态预警;1995年处于黄灯区,2005和2015年继续向良好方向演化,均不需预警,但从发展趋势来看,预计人口密度于2020年左右进入警戒状态。【结论】研究结果与该流域的实际情况相符,该指标体系和生态安全预警模型可以应用于黄土丘陵区。
Resumo:
Copper phthalocyanine doped polymethacrylate Langmuir-Blodgett films were transferred to align a nematic liquid crystal 5CB, It is found that the pre-tilt angle of the liquid crystal can be controlled with the variation of the doped copper phthalocyanine molecular ratio and is correlated with the dichroic ratio of the aligning layer. The polarity of the aligning layer is regarded as the most likely underlying factor that causes the different LC alignment configurations. (C) 1997 Elsevier Science B.V.
Resumo:
针对远距离声源发射的水声信号微弱、水声接收设备电源能量有限的特点,提出一种功耗小、对无源元件误差灵敏度低、高增益放大的微弱水声信号通用放大电路。系统采用场效应管共源单调谐放大器为前置放大级,由四级级联低功耗运放构成带通滤波放大电路,省去传统的R、C低通网络,实现了对微弱水声信号的高增益放大和海洋背景噪声的归一化处理。通过计算电路网络传递函数极点证明了电路系统的稳定性。海上使用表明系统具有精度高、适应性强、电路稳定性好、功耗小等优点。
Resumo:
The Huade Group, consisting of low-grade and un-metamorphosed sedimentary rocks with no volcanic interlayer, is located at the northern margin of the North China craton and adjoining the south part of the Central Asian Orogenic Belt. It is east to the Paleo- to Meso-Proterozoic Bayan Obo and Zhaertai-Langshan rifts and northwest to the Paleo- to Neo-proterozoic Yanshan aulacogen, in which the typical Changcheng, Jixian and Qingbaikou systems are developed. The Huade Group are mainly composed of pebbly sandstones, sandstones, greywackes,shales,calc-silicate rocks and limestones, partly undergoing low-grade metamorphism and being changed to meta-sandstones, schists, phyllites, slates and crystalline limestones or marbles. The stratigraphic sequences show several cycles of deposition. Each of them developed coarse clastic rocks – interbedded fine clastic rocks and pelites from bottom upward or from coarse clastic rocks to interbedded fine clastic rocks and pelites to carbonate rocks. The Tumen Group outcrop sporadically around or west to the Tanlu faults in western Shandong. They are mainly composed of pebbly sandstones, sandstones, shales and limestones. This thesis deals with the characteristics of petrology, geochemistry and sedimentary of the Huade Group and the Tumen Group, and discusses the LA-ICP-MS and SIMS U-Pb ages, Hf isotope and trace element composition of the detrital zircons from 5 meta-sandstone samples of the Huade Group and 3 sandstone samples of the Tumen Group. The age populations of the detrital zircons from the Huade Group are mainly ~2.5 Ga and ~1.85 Ga, and there are also minor peaks at ~2.0 Ga, ~1.92 Ga and ~1.73 Ga. Most of the detrital zircon grains of 2.47-2.57 Ga and a few of 1.63-2.03 Ga have Hf crust model ages of 2.7-3.0 Ga, and most of the detrital zircon grains of 1.63-2.03 Ga have Hf crust model ages of 2.35-2.7 Ga, with a peak at 2.54 Ga. The main age peaks of the detrital zircons from the Tumen Group are ~2.5 Ga、~1.85 Ga, 1.57 Ga, 1.5 Ga, 1.33 Ga and 1.2 Ga. Different samples from the Tumen Group have distinct Hf isotopic characteristics. Detrital zircon grains of ~2.52 Ga from one sandstone sample have 2.7-3.2 Ga Hf crust model ages, whereas zircon grains of 1.73-2.02 Ga and 2.31-2.68 Ga from another sample have Hf crust model ages of 2.95-3.55 Ga. Detrital zircon grains of Mesoproterozoic ages have Paleoproterozoic (1.7-2.25 Ga) crust model ages. Through detailed analyses of the detrital zircons from the Huade and Tumen Group and comparison with those from the sedimentary rocks of similar sedimentary ages, the thesis mainly reaches the following conclusions: 1. The youngest age peaks of the detrital zircons of 1.73 Ga constrains the sedimentary time of the Huade Group from late Paleoproterozoic to Mesoproterozoic. 2. The age peaks of detrital zircons of the Huade Group correspond to the significant Precambrian tectonic-thermal events of the North China craton. The basement of the North China craton is the main provenance of the Huade Group, of which the intermediate to high grade metamorphic sedimentary rocks are dominant and provide mainly 1.85-1.92 Ga sediments. 3. The Huade basin belongs to the North China craton and it is suggested that the northern boundary of the North China craton should be north to the Huade basin. 4. The stratigraphic characteristics indicate the Huade Group formed in a stable shallow-hypabyssal sedimentary basin. The rock association and sedimentary time of the Huade Group are similar to those of the Banyan Obo Group and the Zhaertai Group, and they commonly constitute late Paleoproterozoic to Mesoproterozoic continental margin basins along the northern margin of the North China craton. 5. The continental margin basins would have initiated coeval with the Yanshan and Xiong’er aulacogens. 6. The ages of the detrital zircons from the Tumen Group and the Penglai Group at Shandong peninsula and the Yushulazi Group at south Liaoning are similar, so their sedimentary time is suggested to be Neoproterozoic,coeval with the Qingbaikou system. The detrital zircon ages of 1.0-1.2 Ga from the Tumen Group, the Penglai Group and the Yushulazi Group indicate that there have being 1.0-1.2 Ga magmatic activities at the eastern margin of the North China craton. 7. The U-Pb age populations of the detrital zircons from the late Paleoproterozoic to Neoproterozoic sedimentary rocks suggest that the main Precambrian tectonic-thermal events of the North China craton happened at ~2.5 Ga and ~1.85 Ga. But the events at 2.7 Ga and 1.2 Ga are also of great significance. Hf isotope characteristics indicate that the significant crust growth periods of the North China craton are 2.7-3.0 Ga and ~2.5 Ga.
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Landslide is a kind of serious geological hazards and its damage is very great. In recent years, landslides become more and more frequent along with increase of scale of engineering constructions and cause greater loss. Consequently, how to protect landslides has become important research subject in the engineering field. This paper improves the method how to compute landslide thrust and solves the irrational problem in the design of piles because of the irrational landslide thrust according to the theory and technology of existed anti-slide piles and pre-stressed cable anti-slide piles. Modern pre-stressing technology has been introduced and load balancing method has been used to improve the stressing behavior of anti-slide piles. Anchor cables, anti-slide piles and modern pre-stressing technology have been used to prevention complicated landslide. It is an important base to select values for the landslide thrust. An improved method to calculate design thrust of anti-slide piles has been presented in this paper on the base of residual thrust method by comparing existing methods to select values of landslide thrust in the design of anti-slide piles. In the method, residual landslide thrust behind the anti-slide piles and residual skid resistance before the piles has been analyzed, equitable distribution of residual landslide thrust behind the piles has been realized, and the method to select value of design thrust becomes more reasonable. The pre-stressed cable anti-slide piles are developed from the common anti-slide piles and are common method to prevent landslide. Their principle is that internal force of anti-slide piles is adjusted and size of section is diminished by changing constraint conditions of anti-slide piles. For landslides with deep slip surface and large scale of slopes, limitation of the method appears. Such landslides are in need of long piles and anchor cables which are not only non-economic but also can generate larger deformation and leave potential danger after prevention. For solving the problem, a new kind of anti-slide piles, inner pre-stressing force anti-slide piles, is presented in this paper, and its principle is that an additional force, which is generated in the inner anti-slide piles by arranging pre-stressed reinforcement or tight wire in a certain form in interior of anti-slide piles and stretching the steel reinforcement or tight wire, may balance out the internal force induced by landslide thrust whole or partly (load balancing method). The method will change bending moment which anti-slide piles are not good at bearing into compressive stress which piles are good at bearing, improve stressing performance of anti-slide piles greatly, diminish size of section, and make anti-slide piles not fissured in the natural service or postpone appearance of the fissures, and improve viability of anti-slide piles. Pre-stressed cable anti-slide piles and inner pre-stressing force anti-slide piles go by the general name of pre-stressed structure anti-slide piles in the paper, and their design and calculation method is also analyzed. A new calculation method is provided in the paper for design of anti-slide piles. For pre-stressed structure anti-slide piles, a new computation mode is firstly presented in the paper on the foundation of cantilever piles. In the mode, constraint form of load-bearing section of the anti-slide piles should be confirmed according to reservoir conditions in order to figure out amount of pre-stress of the anchor cables, and internal force should be analyzed for the load-bearing section of pre-stressed structure anti-slide piles so as to confirm anchorage section of anti-slide piles. Pre-stressed cables of the pre-stressed cable anti-slide piles can be arranged as required. This paper analyzes the load-bearing section of single-row and double-row pre-stressed cable anti-slide piles and provides a calculation method for design of the pre-stressed cable anti-slide piles. Inner pre-stressing force anti-slide piles are a new kind of structural style. Their load-bearing section is divided into four computation modes according to whether pre-stressed cables are applied for exterior of the anti-slide piles, and whether single-row or double-row exterior pre-stressed cables are applied. The load balancing method is used to analyze the computation modes for providing a method to design the inner pre-stressing force anti-slide piles rationally. Pre-stressed cable anti-slide piles and inner pre-stressing force anti-slide piles are applied to research on Mahe landfall in Yalong Lenggu hydropower station by the improved method to select value of design thrust of anti-slide piles. A good effect is obtained in the analysis.
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Extensive high to ultrahigh pressure metamorphic rocks are outcropped in the the Dabie-Sulu UHP orogenic belt. Disputes still exist about for protolith nature of metamorphic rocks, petrogenesis, tectonic setting, and influence on upper mantle during the Triassic deep subduction. In this study, a combined study of petrology, geochemistry, isotope geochemistry and zircon chronology was accomplished for high-grade gneisses in the basement of the ultrahigh-pressure metamorphic Rongcheng terrane to reveal protolith nature and petrogenesis of the gneisses and to disucss the magmatic succession along the northern margin of the Yangtze block in Neoproterozoic. Gneisses in the Rongcheng terrane are characterized by negative Nb, Ta, P and Ti anomalies, relatively low Sr/Y ratios and relatively high Ba/La, Ba/Nb and Ba/Zr ratios, mostly displaying geochemical affinity to Phanerozoic volcanic arc. Neoproterozoic protolith ages (0.7 ~ 0.8 Ga) and Paleoproterozoic average crustal residence time (1.92 ~ 2.21 Ga) favour a Yangtze affinity. The gneisses mostly display characteristics of enrichment of LREE, flat heavy rare earth elements (REE) patterns, moderately fractionation between LREE and HREE and slight negative or positive Eu anomalies, probably reflecting that melting took place in the middle to low crust (26 ~ 33 km), where amphibole fractionated from the melts and/or inherited from source material as major mineral phases in the source area. Sr-Nd isotopic composition of the gneisses supports this conclusion. According to εNd(t) and εHf(t) values, the gneisses can be divided into three groups. Gneisses of group I have the highest εNd(t) and εHf(t) values, corresponding to the range of -6 ~ -3 and -2.9 ~ 13.4, respectively. This suggests obvious influx of depleted mantle or juvenile crust in the formation of protoliths. Gneisses of group II have medium εNd(t) (-9 ~ -7) and εHf(t) values (-15.8 ~ -1.4), corresponding to relatively high TDM2(Nd) (1.99 ~ 2.31 Ga) and TDM2(Hf) (1.76 ~ 2.67 Ga) , respectively. This suggests these gneisses were formed by partial melting of Paleoproterozoic crust. Gneisses of group III have the lowest εNd(t) (-15 ~ -10) and εHf(t) values (-15.8 ~ -1.4), corresponding to the largest TDM2(Nd) (1.99 ~ 2.31 Ga) and TDM2(Hf) ( 1.76 ~ 2.67 Ga), respectively. This indicates that gneisses of group III were formed by remelting of Archean crustal material and further demonstrates existence of an Archean basement probably of the Yangtze affinity beneath the Rongcheng terrane. Gneisses of three groups have also certain different geochemical characteristics. Contents of REEs and trace elements reduce gradually from group I to group III. Zirconium saturation temperatures also show similar tendency. Compared to gneisses of group II and group III, gneisses of group I display geochemical feature similar to extensional tectonic setting, having relatively little influence by the source area. Therefore, geochemical characteristics for gneisses of group I can indictate that the protoliths of the Rongcheng gneisses formed in an extensional rifting tectonic setting. This conclusion is supported by the results of eclogites and gabbros previously reported in the Dabie-Sulu orogenic belt. Statistical results of the protolith ages of the Rongcheng gneisses show two age peaks around ~728 Ma and ~783 Ma with an about 50 Ma gap. Extensive magatism in abou 750 Ma along the northern margin of the Yangtze block can hardly be observed in the Rongcheng terrane. This phenomenon likely suggests discontinuous Neoproterozoic magmatism along the northern margin of the Yangtze block.
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Qianmiqiao buried hill, which is a high-yield burial hill pool, was discovered at Dagang oilfield in 1998. To employ the integrated geological and geophysical research at Qianmiqiao area, it is very valuable and meaningful for the petroleum exploration of Bohai Bay Basin and even the whole country. Based on the previous results, this paper is carried out from the research on Huanghua depression, following the law, i.e. the deep part constrains the shallow, the regional constrains the local, takes the geophysical research in Qianmiqiao oilfield, discusses the formation history of burial hills, burial history, thermal history, the generated and expelling history of hydrocarbon, and migration characteristics, probes into the formation of burial hill pool. This paper uses the gravity and magnetic methods which are based on potential field, with natural sources, configures the inner structure of the earth according to the difference in the density and magnetism of the rock. The geophysical characteristics of Dagang oil field is that it is an area with positive Buge gravity anomal. The upheaval of Moho boundary is in mirror symmetry with the depression of the basin's basement. The positive and negative anomaly distributein axis symmetry, and the orientation is NNE. The thickness of the crust gradually reduces from west to east, from land to sea. The depth gradient strip of Curie surface is similar to Moho boundary, whereas their local buried depth is different. Local fractures imply that the orientation of base rock fractures is NNE-NE, and the base rock is intersected by the fractures of the same/ later term, whose orientation is NW, so the base rock likes rhombic mosaic. The results of tomography show that there exists significant asymmetry in vertical and horizontal direction in the velocity configuration of Huanghua depression. From Dezhou to Tianjin, there exits high-speed block, which extends from south to north. The bottom of this high-speed block is in good agreement with the depth of Moho boundary. Hence we can conclude that the high-speed block is actually the crystal basement. According to seismic data, well data and outcrop data, Huanghua depression can be divided into four structure layers, i.e. Pi,2-T, Ji,2-K, E, N-Q. Qianmiqiao burial hills undergo many tectonic movement, where reverse faults in developed in inner burial hill from Indosinian stage to Yanshanian stage, the normal faults extended in Himalayan stage. Under the influence of tectonic movements, the burial hills show three layers, i.e. the reverse rushing faults in buried hills, paleo-residual hill, and extended horst block. The evolution of burial hills can be divided into four stages: steady raising period from Calenonian to early Hercynian, rushing brake drape period from Indosinian to middle Yanshanian, block tilting period in early Tertiary, and heating depression period from late Tertiary to Quaternary. The basin modeling softwares BasinMod 1-D and Basin 2-D, which are made by PRA corporation, are used in this paper, according to the requirement, corresponding geological model is designed. And we model the burial history, thermal history, hydrocarbon generation and hydrocarbon expelling history of Qianmiqiao area. The results show that present bury depth is the deepest in the geological history, the sedimentary rate of Tertiary is highest and its rising rate of temperature rate is higher. During sedimentary history, there is no large erosion, and in the Tertiary, the deeper sediment was deposited in large space, therefore it is in favor of the conservation and transformation of oil and gas. The thermal research shows that the heat primarily comes from basement of the basin, present geotherm is the highest temperature in the geological history. Major source rock is the strata of ES3, whose organic is abundant, good-typed, maturative and of high-expulsive efficiency. The organic evolution of source rock of O has come to the overmature stage, the evolving time is long and the source rock can be easily destroyed. Therefore it is more difficult for the O formation source rock to form the huge accumulation of oil and gas than Es3 formation. In the research of oil assembling, we first calculated the characteristics of the fluid pressure of single well, then analyzed the distribution of the surplus fluid pressure of each formation and profile, and probe the first hydrocarbon migration situation and the distribution of pressure system of buried hill pool. In every formation, the pressure system of each burial hill has its own characteristics, e.g. high pressure or low pressure. In the research of secondary migration, the fluid potential is calculated while the relative low potential area is figured out. In Qianmiqiao area, the west margin faults have the low potential, and hence is the favorable reconnoiter belt.
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胶北煌斑岩分别采自龙口、烟台和威海地区,包括拉辉煌斑岩、斜闪正煌岩和角闪煌斑岩,煌斑岩K—Ar全岩年龄变化于89.3~169.5Ma,为晚中生代岩浆活动的产物。在岩石化学组成上,SiO2=42.02%~54.95%,以钙碱性系列为主.岩石以富集大离子亲石元素(LILE)(Ba,U,K,Th)和LREE,亏损高场强元素(HFSE)(Nb,Ta和Ti)为特征,Mg^#=33.9~53.9,Eu/Eu^*=0.71~0.89,^87Sr/^86Sr初始比值0.707642~0.709791,εNd(t)为-17.6~-10.4,^206Pb/^204Pb=37.588~38.431,^207Pb/^204Pb=15.423~15.531,^206Pb/^204Pb=17.204~18.179。表明煌斑岩源自俯冲陆壳(扬子下地壳)在地幔源区发生交代作用时形成的富集型地幔的部分熔融体.考虑到煌斑岩具有大陆边缘弧玄武岩的特征,我们认为煌斑岩在成因上同样与古大洋板块的俯冲作用有关,为碰撞后弧岩浆作用形成的脉岩。
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In recent years, the deficit of inhibition has become an important reason for explaining addiction. Response inhibition resembles the compulsive drug seeking behavior and it is the basement of addiction inhibition deficits. However, there were no enough evidence for the relationship between addiction and response inhibition deficits and the results of the neuro mechanisms studies remains unclear. Few studies has focused on the exploring the heroin users. Among those paradigms for study response inhibition deficits, stop signal is a very suitable model for the representation of compulsive drug seeking, but only a few researches has worked on this paradigm. In this study, we selected about 100 heroin abusers and had behaviour and neuro imaging scannings for investigating the response inhibition deficits. The behaviour researches found: first, the chronic heroin users had longer reaction time than control group and this reaction time were not affected by stop signals in heroin users. Second, heroin users had less waiting time than control group and they were more impulsive but less flexibility. Their erro monitoring and flexibale adjustment ability decreased. Third, the SSRT of heroin users was significantly longer than control group. These results suggested that the inhibition of heroin users were impaired. Further investigation showed that the SSRT of heroin users had positive correlation of four factor scores of ASI and the macro correlation coefficient was factor three of drug use. This correlation suggested that drug use was the main reason of inhibition deficits. fMRI results mainly focused on the ANOVA analysis for group difference. First, there was no intensity difference in M1 and SMA brain areas between the two groups. Second, heroin users had less activation in right dorsalateral prefrontal cortex, right inferior prefrontal cortex and anterior cingulated cortex, while in bilateral striatum and amygdala, heroin users had more activation than control group. The right prefrontal cortex was indentified as the main inhibition brain area. The anterior cingulated cortex has relationship with erro monitoring and amygdale was an important brain area for impulsivity and emotion control. The network of these brain areas was envovled in impulsivity and inhibition and it was suggested the mainly damaged network for heroin users’ disinhibition. We also investigated the gray matter changes of heroin users and found that chonic heroin use made their gray matter density decreased in prefrontal cortex (including bilateral dorsalateral prefrontal cortex, obital frontal cortex, inferior prefrontal cortex) and anterior cingulated cortex. The gray matter density in these brain regions had negative correlation with drug use duration. In conclusion, we indentified the disinhibition of heroin users and its neuro mechanism. Their compulsivity brain areas had more activation than control group and their inhibition brain areas had less activation than normal control. On the other side, the biological mechanism of this activation changes was the gray matter density decrease in these brain areas.