共查询到20条相似文献，搜索用时 15 毫秒
1.
导数光谱法直接测定混合稀土中钕与铒 总被引：2，自引：0，他引：2
研究了在Tfiton X-100存在下,某些稀土元素与1-苯基-3-甲基-4-苯甲酰基吡唑酮-5形成配合物的4f电子跃迁的光谱性质。拟定了三阶导数光谱直接测定混合稀土中Nd和Er的方法,用于合成样及稀土矿样分析,结果满意。 相似文献
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二纺蛛总科包括5个现生科、5个化石科以及一些科级位置未定的化石物种,是蜘蛛目中较为古老的一个类群。目前已知最早的二纺蛛总科化石记录可以追溯到早侏罗世,但分子系统发育研究推测其起源时间为二叠纪。二纺蛛总科蜘蛛在中生代最为繁盛,化石物种相对较多,是蜘蛛化石类群的重要组成部分。而现生二纺蛛总科蜘蛛十分稀少,且主要分布在热带和亚热带地区。近年来的系统发育研究认为二纺蛛总科可能是复杂生殖器类的姐妹群,是蜘蛛演化研究的关键类群。因此,本文对二纺蛛总科分类系统的研究历史进行了回顾,总结了二纺蛛总科化石类群在不同地质历史时期的组成和分布,统计了二纺蛛总科蜘蛛化石的名录。目前,二纺蛛总科蜘蛛化石分类研究基础薄弱,部分化石类群的系统位置存疑,二纺蛛总科内部系统发育关系尚不清晰。在将来的研究中,需要利用多种技术手段获取化石材料的形态学信息,打好分类学基础;结合化石类群和现生类群进行系统发育分析;进而联系古地理、古生态、生物学行为等研究,全方位分析二纺蛛总科的自然演化历史。 相似文献
4.
二纺蛛总科包括5个现生科、5个化石科以及一些科级位置未定的化石物种,是蜘蛛目中较为古老的一个类群。目前已知最早的二纺蛛总科化石记录可以追溯到早侏罗世,但分子系统发育研究推测其起源时间为二叠纪。二纺蛛总科蜘蛛在中生代最为繁盛,化石物种相对较多,是蜘蛛化石类群的重要组成部分。而现生二纺蛛总科蜘蛛十分稀少,且主要分布在热带和亚热带地区。近年来的系统发育研究认为二纺蛛总科可能是复杂生殖器类的姐妹群,是蜘蛛演化研究的关键类群。因此,本文对二纺蛛总科分类系统的研究历史进行了回顾,总结了二纺蛛总科化石类群在不同地质历史时期的组成和分布,统计了二纺蛛总科蜘蛛化石的名录。目前,二纺蛛总科蜘蛛化石分类研究基础薄弱,部分化石类群的系统位置存疑,二纺蛛总科内部系统发育关系尚不清晰。在将来的研究中,需要利用多种技术手段获取化石材料的形态学信息,打好分类学基础;结合化石类群和现生类群进行系统发育分析;进而联系古地理、古生态、生物学行为等研究,全方位分析二纺蛛总科的自然演化历史。 相似文献
5.
奥斯坦(Orsten)型保存化石是一类个体微小却三维保存软躯体的、表皮次生磷酸盐化的以节肢动物为主的化石。和澄江生物群化石不同的是,奥斯坦型保存化石无明显受垂向挤压变形,是一种特殊的保存方式。奥斯坦型保存化石呈现出精美的生物活体时的形态特征,对研究节肢动物的生长模式、系统分类及个体发育提供了重要的形态证据。二十多年来,中国的古生物学家锲而不舍地在寒武纪地层里找寻这类化石。中国的南方是世界奥斯坦型化石重要的产出地之一,其潜在的化石资源有待深入研究,研究前景具有挑战性。 相似文献
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A suite of Australian shales, greywackes and subgreywackes ranging in age from Proterozoic to Triassic were analyzed for the rare earth elements (REE) in order to detect any secular changes in rare earth distribution. These post-Archean sediments show remarkably similar relative rare earth patterns. They are characterized by negative Eu anomalies of almost constant magnitude (average Eu/Eu* = 0.67 ± 0.05) relative to chondrites and nearly constant ratios of light to heavy rare earths (average ∑LREE/∑HREE = 9.7 ± 1.8).
The REE abundances are generally higher in the younger sediments which may suggest that the absolute abundances of the rare earths in clastic sediments have gradually increased with time. Since no secular change in relative rare earth distribution was detected in the post-Archean sediments, a uniform process of crustal growth and evolution seems to have operated over the past 1500 million years at least.
Australites show rare earth distributions very similar to that of the average clastic sediment. This suggests that the tektite parent material originated in the upper crust. 相似文献
8.
微量元素肥料及稀土肥料应用现状与开发前景 总被引：8，自引：0，他引：8
农作物在生长发育过程中所需的营养元素达16种以上。其中B、Cu、Mo、Zn、Mn、Fe等微量元素及镧系元素（稀土）在提高农作物产量、增强农作物抗逆性能、提高农作物品质等方面具有不容忽视的作用。在研究开发微肥与稀土微肥的同时，也应重视对含多种微量元素及稀土的矿肥的研究与开发。 相似文献
9.
Diminutive trace fossils described here have been well preserved in connection with certain pliable carapaces or skeletons of the Chengjiang animals. Taphonomic evidence suggests that these traces were formed in situ. The peculiar preservation indicates that some bilaterians of uncertain affinities seem to have been active at the burial site, constituting an important group of the hidden majority of Cambrian marine community. This may be an essential feature closely associated with the palaeoecology and exceptional preservation of the Cambrian fossil Lagerstätten. The rare preservation of such millimetre‐sized trace fossils raises further doubts about the timing of the initial benthic bilaterians by applying trace fossil evidence. 相似文献
10.
基于DEM的南岭东段离子吸附型稀土矿成矿地貌条件分析 总被引：1，自引：0，他引：1
稀土是我国重要的战略资源,而离子吸附型稀土矿是我国的特色矿产,占据着重要的地位。离子吸附型矿产的形成与否,与风化壳密切相关,而风化壳的发育及保存与微地貌等特征密切相关。本文旨在利用DEM技术,结合搜集到稀土矿点及矿区数据,对含有稀土的地貌单元进行地形因子定量分析,以总结风化壳离子吸附型稀土矿的成矿地貌条件。借助GIS技术,利用DEM提取高程、坡度、坡向、曲率、地形起伏度、地表切割深度、地形特征等各类地貌因子值,并与南岭东段的成矿矿点及矿区进行叠加分析,统计计算矿点及矿区所处位置的地貌因子值,进而探讨风化壳型稀土资源赋存的有利地形地貌环境。结果显示,最佳成矿有利地貌为高程150~500 m、坡度0°~20°、地形起伏度100~400 m、地表切割深度40~150 m、地形特征为山顶或山脊;研究结果有望指导南岭东段离子吸附型稀土矿找矿勘查工作。 相似文献
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Benjamin P. Kear Andrew R. Milner Paul M. Barrett 《Proceedings of the Geologists' Association. Geologists' Association》2009,120(2-3):121-125
Plesiosaur fossils from the uppermost Tithonian (Upper Jurassic) to lower Valanginian (Lower Cretaceous) Purbeck Limestone Group of Dorset, England are important because they constitute a rare record from around the Jurassic-Cretaceous boundary. Where diagnostic, the remains are referred to indeterminate plesiosauroids (Cryptocleidoidea) and represent relatively small animals including a previously undescribed juvenile individual. This observation accords with the lagoonal-lacustrine (with periodic marine influx) depositional setting of the Purbeck Limestone Group strata, a palaeoenvironment that is often associated with juvenile plesiosaur occurrences. 相似文献
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GEOLOGICAL SIGNIFICANT OF SPOROPOLLEN ASSEMBLAGE IN THE XUESHAN FORMATION 相似文献
14.
硫酸铵溶液淋滤-电感耦合等离子体质谱测定离子相稀土分量的方法优化 总被引：2，自引：2，他引：0
离子吸附型稀土中离子相稀土的准确测定对稀土矿体资源评价具有重要意义。离子相稀土以羟基或水合羟基的形式吸附在黏土矿物上,可与强电解质(Mg~(2+)、NH_4~+等)交换解吸进入溶液。前人以硫酸铵为淋滤液,实现了离子相稀土的解吸、提取,但在溶液浓度、浸取过程等方面选择各异,淋滤浸取率(60%～90%)差异大,未形成高效、统一的浸取方法,不利于离子相稀土元素的精确测定。本文通过对比实验规范了硫酸铵淋滤离子相稀土的各项淋滤参数(固液比、硫酸铵浓度、样品最佳称样量、浸泡时间),减少了淋滤过程中离子相稀土的损失,浸取率达到88%～98%,进而利用ICP-MS测定离子相稀土分量。方法检出限为0. 05～5. 11 ng/g;三类岩性离子吸附型稀土样品的精密度为:火山岩1. 80%～10. 01%,变质岩1. 06%～7. 27%,沉积岩1. 72%～7. 58%。协作实验室的分析结果验证了本方法的可靠性和准确性。本方法操作简便,分析效率高,为建立相关的行业标准乃至国家标准奠定了基础。 相似文献
15.
晚新元古代瓮安生物群研究新进展 总被引：2，自引：0，他引：2
产于贵州瓮安，福泉，开阳地区晚新元古代陡山陀期磷块岩中的多细胞藻类，大型带刺疑源类，蓝菌丝状体和细菌化石，球状微体化石，后生动物化石等构成的瓮安生物群是世界上目前发现保存最完美的一个古生物群之一，本文在简单介绍翁安生物群研究现状的基础上，首次批露了笔者近些年来觅获和初步研究的单细胸原生动物，多细胞类海绵动物和类腕足类后生动物等一批新的动物化石资料，为地球早期动物起源，早期生物组织分化，适应辐射，生物多样化和早期海洋生物生态系统提供了珍贵的化石实证材料，此外，还论述了瓮安生物群发现的科学意义。 相似文献
16.
WANG Xin CUI Jinzhong 《《地质学报》英文版》2007,81(1):16-22
For a long time, paleontologists have been focusing on hard parts of organisms during different geological periods while soft parts are rarely reported. Well-preserved plant cells, if found in fossils, are treated only as a rarity. Recent prowess in research on fossil cytoplasm indicates that plant cytoplasm not only has excellent ultrastructures preserved but also may be a quite commonly seen fossil in strata. However, up to now there is no report of plant cell fossils in China yet. Here plant cell fossils are reported from Huolinhe Coal Mine （the early Cretaceous）, Inner Mongolia, China. The presence of plant cytoplasm fossils in two cones on the same specimen not only provides further support for the recently proposed hypothesis on plant cytoplasm fossilization but also marks the first record of plant cytoplasm fossils in China, which suggests a great research potential in this new area. 相似文献
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Gyrolithes为螺旋形垂直居住潜穴,是具成对附肢的两侧对称甲壳类所建造,出现在近海泻湖和河口湾等边缘海和极浅海环境中,常与半咸水条件有关。塔里木盆地塔中地区诸多钻井的下志留统塔塔埃尔塔格组上部大量发育有此类潜穴,在局部层位可形成强烈的扰动构造。伴生的遗迹化石很少,只有极个别的Beaconites。根据沉积学、地球化学和古生态学特征,这类潜穴形成在半咸水的泻湖环境中。这类潜穴外壁基本平直,在泥质沉积物中掘穴深度大而不变形,而且其充填物与围岩完全不同,这些特点表明Gyrolithes为固底控制的遗迹化石。 相似文献
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The authors have used a high-purity multielement solution, containing known quantities of individual Pare earth elements, as a reference standard in neutron activation analysis of rare earths in several international standard rocks. The data obtained by the authors have been compared with those obtained using the international standard rock Basalt BCR-1 as a reference material. The authors'data compare favourably with those obtained by other workers, particularly for the more basic rock types, and encourages the authors to suggest that a multielement solution standard can be used successfully for neutron activation analysis of rave earth elements. High values obtained for Ce in Basalt BCR-1, however, might indicate that the behaviour of Ce in solution needs further investigation. 相似文献
19.
《International Geology Review》2012,54(1):9-25
Ta and Nb are associated in nature. Both are oxyphile and are related geochemically to Fe, Mn, Ti, rare earths U, Th, Zr, W, Sn, Bi, and Sb. Both accompany the alkali metals,especially Na and Li. Their close relationship explains their isomorphism in mineral-forming processes. Zr, W, and Sn entrain Ta and Nb in the crystal lattices of their minerals in limited amounts. The concentration of Ta and Nb increases in the course of magma evolution from ultrabasic to alkalic. Nb predominates over Ta in the main kinds of rocks by from 5:1 to 17:1. Only in granite pegmatites is Ta dominant. In granitic rocks Ta and Nb are associated with Fe, Mn, Bi, Sb, W, and Sn. In granosyenitic complexes they form complex minerals with Ti, rare earths of the Y subgroup, U, and Th. Concentrations of Ta and Nb in granitic and granosyenitic complexes increase toward the end of the magmatic and pegmatitic processes, and afterward diminish toward the end of the pneumatolytic-hydrothermal processes. In alkalic complexes Ta and Nb are associated with Ti, rare earths of the Ce group, and Th. Concentrations of Ta and Ni in alkalic massifs are caused by magmatic differentiation. In alkalic ultrabasic complexes, in magmatic and pegmatitic processes, Ta and Nb do not form independent minerals but enter into minerals of Ti and Fe, i. e. perovskite, titanomagnitite, and pyroxenes. --M. Russell. 相似文献
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文章运用岩石地球化学方法,对桂岭岩体的构造环境和地球化学特征进行了研究,结果显示：桂岭岩体岩石平均LREE／HREE=7．68,（La／Yb）N-6．77,（La／Sm）N-4．65,（Gd／Yb）N-1．04,平均δEu=0．45〈1,表明轻重稀土轻度分异,轻稀土相对富集,轻稀土内部分馏明显,存在负铕异常;岩体明显亏损Nb、Sr、Ti,显示桂岭岩体的源区可能主要来自地壳,是地壳环境下壳源岩石发生部分熔融的产物;研究表明,桂岭岩体形成于挤压一伸展的大地构造环境。 相似文献