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云南种子植物区系地理成分分布格局及其意义 总被引：5，自引：1，他引：4
以覆盖云南全境的31个地区植物区系研究报告为基础, 使用Arcview软件制作了14个种子植物属的地理成分多度分布图。 对这些种子植物属的多度分布格局进行分析,获得以下结果:①热带成分合计占所统计的地区植物区系属的29.6%~94.1%, 其最小值是在云南西北部, 最大值出现在云南南部; 温带成分合计占所统计的地区植物区系属的6%~70.4%, 其多度分布恰与热带成分相反。②在热带成分中, 全热带分布属占13.64%~46%, 居热带成分之首, 其最大值出现在云南怒江和元江的干热河谷; 热带亚洲分布属占3.33%~42.26%, 最大值出现在云南南部。③在温带成分中, 北温带分布属占所统计的地区植物区系的2%~30.39%, 居温带成分之首, 最大值出现在云南西北部山地, 其次是东亚分布属, 占2%~14.57%, 最大值出现在滇西北横断山区。④在与云南植被的关系上,热带亚洲分布属、旧世界热带分布属和热带亚洲至热带大洋洲分布属是云南热带森林的主要成分; 全热带分布属和热带亚洲至热带非洲分布属是干热河谷植被的主要成分,北温带分布属主要出现在冷湿山地森林植被中,而东亚分布属、东亚和北美洲间断分布属及旧世界温带分布属与温凉气候地区的森林植被联系相对密切。⑤生物地理上,云南种子植物属的多度分格局暗示了所谓的“田中线”在印度—马来西亚热带植物区系与东亚亚热带—温带植物区系的地理界限上有意义;热带亚洲至热带非洲分布属主要存在于云南的干热河谷,暗示了干热河谷植被具有一定非洲亲缘;云南西部的热带性很强,暗示了在印度板块同亚洲板块相撞、推挤北移及喜马拉雅隆升过程中, 云南西部至东南部的地块可能发生了顺时针转动。⑥在云南, 不论其纬度, 只要是海拔低的区域都是热带区域, 支持云南应是一个基带为热带的大的山原观点。 相似文献
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本文根据从云南西部耿马采集的大量的腕足类Stereochia属标本,以及详查资料的比较,对Stereochia属和Costiferina属的特征和成员进行了深入的讨论。通过对属种的修订,理清了两个属的地质时代和地理分布。结果表明,Stereochia属的地质历程主要是早二叠世Sakmarian期至晚二叠世Dzhulfian期;Costiferina属出现时期比Stereochia属晚,主要分布在早二叠世Baigendzinian期至晚二叠世Djulfian期。上述两属对确定冈瓦纳大陆北缘海边界有重要意义,Stereochia常与(竹蜓)类和珊瑚化石共生,生活在温暖清澈水体中。古地理上,它分布在冈瓦纳大陆北缘海边界,属于浅海地台型沉积范围;Costiferina常出现于碎屑岩中,与之共处的化石多为个体巨大、壳壁厚的Fusispirifer,很少与(竹蜓)类和珊瑚类在一起,表明它生活在冈瓦纳大陆北缘海的靠大陆一侧,这里陆源碎屑丰富,海水混浊,并相对偏冷。 相似文献
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滇西古特提斯多岛洋的结构及其南北延伸 总被引：42，自引：3，他引：39
在深化滇西古特提斯构造古地理格局研究基础上 ,提出了区分多岛洋与多岛海的时、空尺度标准。根据藏北羌塘、泰国北部与滇西古特提斯沉积地质学的比较研究 ,论证了滇西昌宁—孟连带北延连接冈玛错缝合带 ,南延与泰国北部隐蔽缝合带相接。泰国东北部著名的难河—程逸缝合带北延很可能潜伏于思茅盆地中新生代红层之下 ,因此古特提斯阶段并不存在稳定的“思茅地块”。泰国西北部湄萨良带存在洋盆硅质岩、海山碳酸盐岩和被动陆缘碎屑岩的构造混杂沉积组合 ,原属“泥盆系”的硅质岩中已发现早石炭世和晚三叠世卡尼期放射虫动物群 ,启示了古特提斯东段存在双子星座式主支洋盆的构造古地理格局。湄萨良带北延最可能与保山地块、腾冲地块之间的潞西三台山蛇绿混杂带相连。滇西北地区原属晚三叠世哈工组内侏罗纪放射虫化石的发现等 ,启示了青藏高原三江带在古、新特提斯转折期古地理演化的复杂性 相似文献
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滇西北甘孜-理塘构造带放射虫地层、硅质岩地球化学及其构造古地理意义 总被引：3，自引：0，他引：3
滇西北香格里拉地区上三叠统哈工组由砂岩、粉砂岩和泥岩组成,并发育大量的沉积混杂岩块。硅质混杂岩块中含有大量的放射虫及竹节石生物化石。放射虫自中泥盆世到中三叠世均有分布,竹节石时代为中泥盆世。不同时代的硅质岩均为生物成因硅质岩,其Al2O3/(Al2O3+Fe2O3)比值介于0.58～0.96之间。北美页岩标准化的稀土模式比较平坦,具弱的Ce负异常或明显的正异常,Eu异常不明显,总体表现为大陆边缘型硅质岩的特征。生物组合和地球化学特征说明甘孜-理塘盆地自早泥盆世裂开。根据硅质岩和硅质泥岩的稀土元素特征,该盆地演化经历了中泥盆世至早石炭世早期缓慢扩张的构造活动期和早石炭世晚期至早三叠世的快速扩张期,以及中三叠世晚期的向西俯冲阶段。晚三叠世,甚至侏罗纪,该盆地仍然发育有深水沉积环境。 相似文献
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Genetic diversity and structure of natural and transplanted eelgrass populations in the Chesapeake and Chincoteague Bays 总被引：1，自引：0，他引：1
The objective of this study was to gain baseline population data on the genetic diversity and differentiation of eelgrass (Zostera marïna L.) populations in the Chesapeake and Chincoteague bays. Natural and transplanted eelgrass beds were compared using starch gel electrophoresis of allozymes. Transplanted eelgrass beds were not reduced in genetic diversity compared with natural beds. Inbreeding coefficients (FIS) indicated that transplanted eelgrass beds had theoretically higher levels of outcrossing than natural beds, suggesting the significance of use of seeds as donor material and of seedling recruitment following transplantation diebacks. Natural populations exhibited very great genetic structure (FST=0.335), but transplanted beds were genetically similar to the donor bed and each other. Genetic diversity was lowest in Chincoteague Bay, reflecting recent restoration history since the 1930s wasting disease and geographical isolation from other east coast populations. These data provide a basis for developing a management plan for conserving eelgrass genetic diversity in the Chesapeake Bay and for guiding estuary-wide restoration efforts. It will be important to recognize that the natural genetic diversity of eelgrass in the estuary is distributed among various populations and is not well represented by single populations. 相似文献
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对云南高原环境演化研究的重要性及环境演变的初步认知 总被引：6，自引：1，他引：5
云南高原是我国四大高原重要组成部分之一。相比较而言,云南高原环境演化及其资源环境效应研究较零星,不够系统深入。对云南高原环境演变进行研究有助于解决云南高原环境演化的独特性和有助于地球系统科学的发展,有助于西部大开发的实施和脱贫致富与可持续发展。云南高原环境演化从第三纪的云南"准平原"形成后受云南运动(青藏运动B幕)的影响,使夷平面位移解体,现代地貌和水系格局逐步形成,由古季风气候控制转化为东南季风、西南季风共同交互影响,出现了生物多样性、生态环境多样性、资源多样性等多种特征,也影响到民族多样性、文化多样性等,使云南高原成为我国西南地区的"宝地"之一。 相似文献
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一株黑曲霉对磷矿石的风化作用 总被引：1，自引：0，他引：1
以一株分离于植物根际土壤且有较强溶磷能力的真菌研究其对磷矿石的风化作用。对该菌株的ITS序列进行PCR扩增及序列测定后,再结合该菌株的形态特征对其进行鉴定,结果为黑曲霉(Aspergillus niger)。用ICP-OES测定培养液中的Ca2+浓度,磷钼比色法测定可溶性磷的含量,电子探针、透射电镜和能谱仪分析菌株作用后的残留物。培养液中的Ca2+浓度由第3天的10.02mg/L增加到第30天的217.61mg/L,可溶性磷的浓度由第3天的5.37mg/L增加到第30天的921.37mg/L;风化过程中形成了大量的次生矿物草酸钙,大分子有机物形成的生物膜以及菌丝体穿插破坏矿物颗粒促进磷矿石的风化。表明该菌株对磷矿石有较强的风化能力,黑曲霉生长产生的生物物理破坏作用和胞外分泌物的生化降解作用是引起磷矿石风化的主要因素。 相似文献
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Paul N. Taylor Stephen Moorbath Roy Goodwin Anne C. Petrykowski 《Geochimica et cosmochimica acta》1980,44(10):1437-1453
Ph isotopic analyses are reported for 119 samples of late Archaean (ca. 3000-2800 Myr) calc alkaline orthogneisses and associated anorthosites from southern West Greenland. Over most of the area. whole rock isotope systematics indicate derivation of the magmatic precursors of the gneisses and anorthosites from a source region with a typically mantle-type ratio (μ1 value of 7.5) at. or shortly before, ca. 3000-2800 Myr ago. In contrast, in the Godthaabsfjord region, late Archaean Nûk gneisses and associated anorthosites were emplaced into or through early Archaean (ca. 3700 Myr) Amîtsoq gneisses, and crystallised with variable proportions of two isotopically distinct types of Pb which commenced their respective crustal developments at ca. 3000-2800 Myr and at ca. 3700 Myr ago. Isotopic and other geochemical constraints demonstrate that Nûk gneisses and their temporal equivalents were not produced by reworking or melting of Amîtsoq gneisses. Mixing of early and late Archaean Pb results from contamination of the magmatic precursors of Nûk gneisses and anorthosites (characterised by mantle-type Pb at time of emplacement) with ancient, unradiogenic Pb derived from ca. 3700 Myr-old Amîtsoq-type continental crust invaded by the Nûk magmas. The contaminant is considered to be a trace-element enriched fluid phase released from dehydrating older continental crust during progressive burial and heating by emplacement of calc alkaline magmas in the late Archaean ‘accretion differentiation superevent’. This was followed by mixing of the released fluids with younger Nûk magmas.Pb isotopic compositions of late Archaean gneisses and anorthosites outside the Godthaabsfjord region provide no evidence for the presence of early Archaean Amîtsoq-type continental crust in southern West Greenland in areas more than a few tens of km outside the known outcrop of Amîtsoq gneisses. We suggest that early Archaean crust does not exist at depth in late Archaean areas with undisturbed Pb-isotope systematics, either in Greenland or elsewhere in the North Atlantic craton.Pb-isotope evidence for crust magma interaction, involving selective extraction of certain trace elements by a fluid phase from wall rock and subsequent mixing between magma and contaminant fluid, provides a powerful tool for detection, sub-surface ‘mapping’, and geochronological and geochemical characterisation of deep, ancient continental crust. 相似文献
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华南地区众多埃迪卡拉纪—寒武纪特异埋藏化石库为解读生命和生态系统的演化提供了重要化石证据,其中宏体藻类产出数量多、分布广、形态多样,是该时期生态系统中不可忽视的组成部分。过去对华南宏体藻类的研究多集中于形态、分类和古生态方面,对于其不同时期的地理分布和多样性变化较少涉及。文中对华南埃迪卡拉纪—寒武纪特异埋藏化石库中的宏体藻类进行了总结和分析,结果发现：(1)至晚埃迪卡拉世,宏体藻类的古地理分布范围和属、种级多样性明显扩大和提高,在晚埃迪卡拉世第五期达到顶峰;(2)寒武纪纽芬兰世宏体藻类的地理分布范围和属、种级多样性均较低,至第二世则明显扩大和增加;(3)苗岭世之后,宏体藻类古地理分布大幅度缩小,但多样性显著升高并达到第二高峰,直到芙蓉世多样性又急剧下降。推测区域海水含氧量的增加可能是导致华南宏体藻类繁盛(属、种多样性高)的主要原因,适合宏体藻类保存的泥页岩的分布范围或出露面积则可能是影响宏体藻类古地理分布范围的重要因素。 相似文献
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海扇类（pectinoids (s.l)）是一类具浮游异养幼虫类型生态特征的表生双壳类。这种生态特征决定了其大部分组成分子具世界性分布。但是,在侏罗纪原大西洋地区海扇类中仍有不少属/亚属显示出地区性特征,其地理分布主要受纬度气候带控制,即显示出南北差异。这些地区性海扇贝类是认识侏罗纪生物地理分区的重要标志。主要分布于高纬度地区的北方型分子由Buchiidae、Pectinidae和Oxytomidae 3科的一些属/亚属组成,它们于中侏罗世晚期和晚侏罗世常见于格陵兰东部,往南止于英格兰南部,是北方生物区的重要代表。适于热带－亚热带的特提斯型分子分异度较高,组成分子来自Pectinidae,Spondylidae和Entoliidae 3科,主要分布于法国以南的较低纬度地区。但是,在特提斯海扩张时期,如侏罗纪巴通期,随着特提斯生物大区北界的北移,特提斯双壳类可散布至英格兰北部。 相似文献
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T. V. Klets 《Stratigraphy and Geological Correlation》2008,16(5):467-489
Geographic differentiation of conodontophorids between northern and southern latitudes commenced in the Triassic since the early Induan. Cosmopolitan long-lived genera of predominantly smooth morphotypes without sculpturing were characteristic of high-latitude basins of the Panboreal Superrealm. Since the early Olenekian until the Carnian inclusive, this superrealm consisted of the Siberian Realm that extended over Northeast Asia and the Canada-Svalbard Realm that included the Svalbard Archipelago and northern regions of Canada. Throughout the Triassic period, conodontophorids characteristic of the Tethys-Panthalassa Superrealm spanning the Tethys and low-latitude zones of the Pacific were highly endemic, very diverse in taxonomic aspect, having well-developed sculpturing and tempos of morphological transformations. Distinctions between the Early-Middle Triassic conodontophorids from northern and southern zones were not as great as afterward, and their impoverished assemblages from southern Tethyan basins were close in some respects to the Boreal ones. Their habitat basins of that time can be grouped into the Mediterranean-Pacific and India-Pakistan realms. Hence, the extent of geographic differentiation of conodontophorids was not constant and gradually grew, as their taxonomic diversity was reducing in northern basins but relatively increasing in southern ones. The Panboreal e Tethys-Panthalassa superrealms of conodontophorids, which are most clearly recognizable, are close to first-rank paleobiochores (superrealms) established earlier for ammonoids and bivalve mollusks. Main factor that controlled geographic differentiation of Triassic conodontophorids was climatic zoning. Initially lower diversity of southern Tethyan assemblages points probably to relatively cooler water regime in the peri-Gondwanan part of the Tethys. The established patterns in geographic distribution of conodontophorids characterize most likely the real trend of their differentiation and evolution, i.e., the distribution area contraction prior to complete extinction at the end of the Triassic 相似文献
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《Comptes Rendus Geoscience》2008,340(9-10):602-614
The long-term changes of the mammalian diversity of the Quercy and Limagne area (Massif Central, France) is quantitatively investigated through a ∼16-Myr time span running from the late Middle Eocene (∼38 Myr) to the Early Miocene (∼22 Myr). Within the specific context of ecosystem response to extreme climatic events, the goal of such a deep-time approach to local community and regional metacommunity evolution is to give time-scaled reference series with which extant changes can be objectively compared. The results indicate that local and regional ecological integration levels show very distinct evolutionary dynamics, involving at least partially independent sets of controlling parameters; those driving the metacommunity still remain largely to be better understood. Clearly, the analyzed data set constitutes a rather unique deep-time key into several major current macroecological debates. 相似文献
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云南中甸地区浪都高钾中酸性侵入岩的地球化学特征 总被引：4，自引：0，他引：4
中甸地区浪都中酸性侵入岩在空间上与浪都夕卡岩型铜矿床共生,主要由石英二长斑岩、石英闪长斑岩和花岗闪长斑岩组成。这些侵入岩大多表现出高钾(K2O大于3%)的特征,在K2O-SiO2图上所有样品均落入高钾钙碱性和钾玄岩区域。在稀土元素球粒陨石标准化图上表现为轻稀土富集、重稀土亏损(LaN/YbN=14.3～21.2)、铕弱负异常至无异常(δEu=0.77～1.00);在原始地幔标准化微量元素蛛网图上,K、Rb、Sr、Ba等元素表现出正异常,而Nb、Ta和Ti等元素表现出负异常的特征。浪都侵入岩的87Sr/86Sr初始值为0.7044～0.7069,εNd(t)值为-2.8～-2.2。结合主量、微量元素及Sr-Nd同位素组成,本研究认为浪都岩浆来源于交代地幔,很可能受到了俯冲带流体交代和地壳物质混染的影响,表明浪都中酸性侵入岩的形成与甘孜-理塘洋的俯冲有关。 相似文献
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滇东、桂东北地区泥盆纪灰岩的微相及其形成环境分析 总被引：1，自引：0，他引：1
在云南的曲靖、盘溪和广西的桂林、阳朔地区，中、晚泥盆世的海相灰岩广泛分布，根据微相特征划分出１３种微相类型．它们代表５种不同的沉积环境。沉积环境的分异与当时的海底地形和海平面的升降密切相关。 相似文献
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文中详细描述了云南东部地区早寒武世关山动物群中的典型分子Tuzoia sinensis Pan,对其形态特征做出了补充,通过与相关种的比较与讨论,对其鉴定方法做出了进一步探讨,并基于对壳体表面网格密度的研究推测了T.sinensis的俯视形态图。研究发现：T.sinensis的侧脊上分布有一系列锥状突起,这些突起的表面具有与壳体表面相同的网状纹饰,这提示Tuzoia侧脊上的基部宽大的三角形刺（frills）即由这种锥状突起侧压保存而形成;研究还发现：T.sinensis的三角形刺较其它种更为发达,其壳体在保存过程中易产生形变,但多而发达的三角形刺受后期改造影响较小,因而建议可以将其作为T.sinensis的典型鉴定特征之一而区别于其它种。 相似文献
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滇西北红粘土的工程地质特性及其灾害效应 总被引：1，自引：0，他引：1
在野外地质调查的基础上,结合室内土工试验,系统分析了滇西北红粘土的物质组成、物性特征和工程地质特性,并以此为基础探讨了其地质灾害效应。研究结果表明：滇西北红粘土粒度组成主要以粘粒为主,粘土矿物成分比较复杂,在丽江以南其矿物成分主要以高岭石（K）为主,在丽江以北则以伊利石/蒙脱石（I/S）混层矿物为主。此外,滇西北红粘土具有含水量高、重度低、塑性高、膨胀性弱等物性特征,在天然状态下比较稳定,但是随着含水量的增加其土体强度大大降低,易引发滑坡、水土流失等地质灾害。 相似文献