唐古拉山中侏罗统缅甸光牡蛎(Liostrea birmanica REED)壳层的事件沉积成因及其环境意义     

阴家润  史晓颖  苟金  雷振宇 《现代地质》1992,6(3):254

唐古拉山地区中侏罗统产出丰富的牡蛎类化石,特别是缅甸光牡蛎Liostrea bir—manica Reed分布更为广泛,而且多以介壳层形式产出。在唐古拉山的冬曲,窝布茸曲及青藏公路108道班等地剖面上,栖息于软基底的表生底栖双壳类Liostrea birmanica形成近原地埋葬的介壳层堆积;内生的Ceratomya动物群则多散布于沉积物中,形成原地埋葬的化石群．它们和以丛藻迹Chondrites为主体的遗迹化石群依次重复出现,构成一个和风暴沉积事件相关的底栖动物群替代序列。Liostrea birmanica介壳层是风暴高峰期的侵蚀和再沉积所形成的,风暴期以后水下沉积间断所形成的轻度固化的软基底则迅速地被潜穴生物占领(丛藻迹Chondrites ich—nosp．和根珊瑚迹Rhizocorallium ichnoSp．);而以深挖穴滤食类型为主的Ceralomya组合则是好天气时的原地埋葬。在大多数情况下,它们指示着介于正常浪基面以下,风暴浪基面以上的低沉积速率浅水碳酸岩台地沉积环境。  相似文献   

基于天然红层材料的软岩成型模拟研究     

周翠英  孔令华  崔光俊  于磊  刘镇 《岩土力学》2020,41(2):419-427

岩石模拟是岩土工程模型试验、地质岩芯模拟试验等研究的核心。但目前基于人工材料的模拟制备受限于现有相似理论与技术手段,成岩结果与实际岩性差异较大,特别是软岩的成型模拟问题尤为突出。以天然红层材料为原料,改进传统的成岩模拟系统,考虑成岩过程中温度、孔隙流体压力及上覆压力的分阶段影响,模拟红层软岩从松散岩土颗粒到岩石的形成过程,得到工程标准尺寸软岩岩芯。通过与天然红层软岩进行成岩过程、物理性质、化学性质及力学性质的对比研究表明,以天然红层为原料的软岩岩芯与天然红层软岩性质相似。该研究突破了人工材料配制、3D打印等方法一般只能满足某一方面性质的局限,为大量不同功能需求的软岩岩芯研究提供了新的制作思路与方法。  相似文献   

冀西北张北康保一带新生代红层的地质特征   总被引：1，自引：0，他引：1  

王行军  关晓燕  张德生  朱更新  王德强  班长勇 《华北地质》2005,28(1):39-46

冀西北坝上高原的张北、康保等地发育着两套新生代红层,分别为上新世石匣组和中更新世赤城组。石匣组为一套深红、绛红色的粘土、砂砾层,岩性、岩相交化大,其中含有丰富的具铁锰质薄膜的钙质结核和黑色锰质斑点,并有丰富的三趾马动物群化石和孢粉。孢粉中喜暖喜湿分子约占19％,形成于炎热湿润气候条件下,与现代北亚热带气候条件相似。赤城组为一套冲洪积红黄色亚粘土夹棕红色粘土、砂组成,分布较为局限,含个体小、形状不规则的钙质结核,并有周口店动物群的化石分子和孢粉。孢粉中以中性喜温的松属占绝对优势,喜暖喜湿的分子约占7．6％,形成于温和较湿润气候条件下。  相似文献   

Analcime: A characteristic authigenic phase of andean alluvium,northern chile     

Adrian Hartley  Stephen Flint  Peter Turner 《Geological Journal》1991,26(3):189-202

Analcime (NaAlSi₂O₆.H₂O) forms a characteristic authigenic phase in Andean alluvium of northern Chile. Three stratigraphic units ranging from the lower Cretaceous to the Miocene were studied in order to investigate the presence of analcime in diagenetic assemblages of different ages. The units were deposited in forearc, foreland/back-arc, and intra-arc basinal settings. Characteristics of other sedimentary analcime occurrences were examined in order to define conditions favourable for analcime precipitation. Zeolite zonation and evidence for the original presence of volcanic glass, common to many sedimentary analcime occurrences, are absent in the studied units. Analcime precipitation requires a high Na⁺/H⁺ ratio, relatively low Si⁴⁺/Al³⁺ activity and low H₂O activity. Diagenetic examination of the three stratigraphic units revealed early quartz and feldspar overgrowths, mechanical clay infiltration, and dissolution of labile rock and mineral fragments, particularly intermediate plagioclase (An_30–80). Conditions for these processes are favoured by oxidizing groundwater at near neutral pH. Later diagenesis involved the precipitation of analcime, non-ferroan calcite, quartz, and authigenic clays as the main cementing phases. These formed due to the concentration of oxidizing groundwater and resulted from its continued reaction with detrital feldspars and rock fragments of andesitic and dacitic composition. Analcime precipitation in Andean alluvium resulted from the evolution of saline, alkaline brines under an arid, evaporative climate in closed hydrographic basins with circulating groundwater systems.  相似文献   

马氏珠母贝(Pinctada fucata)血细胞转录组测序数据中SNP标记的开发及其功能注释分析     

王忠良  丁燏  许尤厚  王蓓  张健东 《海洋与湖沼》2018,49(2):403-412

本文基于马氏珠母贝(Pinctada fucata)血细胞比较转录组学数据进行单核苷酸多态性标记(SNP)的开发和关联基因的功能注释分析,以期为SNP标记的利用提供有效信息。在转录组测序获得的67632条SNP-unigenes中共获得962995个SNP位点,位点平均发生频率约为1个SNP/100bp;转换SNP数目与颠换SNP数目比值约为0.5,与理论比率相符;而6种单核苷酸变异类型中,以A/T颠换SNP最多。SNP-unigene功能注释分析表明,30376条unigenes(44.91%)匹配到GO分类条目;18150条unigenes(26.84%)获得COG注释信息,并以"一般功能预测"类最多;10981条unigenes(16.24%)富集到32条KEGG子集,其中以"信号转导"子集中富集的SNP-unigene最多。进一步富集分析显示629个SNP-unigenes注释到"Platelet activation"等多条免疫防御相关信号通路中;同时,根据SNP位点分布情况筛选到123个溶藻弧菌感染前、后转录组中特异分布的免疫防御相关候选SNP位点。基于标准化的基因表达水平分析,在17个差异表达免疫防御相关基因中共检测到1594个SNP位点。  相似文献   

黄鳍棘鲷微卫星标记开发及其在鲷科鱼类中的跨物种扩增          下载免费PDF全文

吴仁协  翟云  肖瑶  牛素芳  张浩冉  黎晓  陈伟勇 《应用海洋学学报》2019,38(3):356-364

采用基于高通量测序平台的SLAF-seq技术,开发出47个高多态性的黄鳍棘鲷(Acanthopagrus latus)微卫星标记,其中二碱基重复位点17个,三至六碱基重复位点30个。各位点的等位基因数为2～27(均值为10),观测杂合度(Ho)和期望杂合度(He)分别为0. 156～0. 938(均值为0. 682)和0. 177～0. 963(均值为0. 741),多态信息含量(PIC)为0. 166～0. 946(均值为0. 705)。经Bonferroni校正后,有43个位点符合哈迪-温伯格平衡(HWE),其余4个位点偏离HWE。这些多态性微卫星标记为黄鳍棘鲷遗传资源研究提供新的有效分子标记。跨物种扩增结果显示,共有31个黄鳍棘鲷微卫星标记可在9种鲷科鱼类中成功扩增。其中17个标记在太平洋棘鲷(Acanthopagrus pacificus)、黑棘鲷(Acanthopagrus schlegelii)和澳洲棘鲷(Acanthopagrus australis)中具有较好的通用性,这些标记可为棘鲷属(Acanthopagrus)的系统进化和种群遗传学分析提供新的标记来源;另有3个标记在二长棘梨齿鲷(Evynnis cardinalis)、真赤鲷(Pagrus major)、蓝点赤鲷(Pagrus caeruleostictus)及黄牙鲷(Dentex hypselosomus)中具有通用性。  相似文献   

大珠母贝微卫星DNA标记的分离与筛选   总被引：2，自引：0，他引：2  

柳明  喻达辉  黄桂菊 《海洋科学》2010,34(8):1-5

采用生物素标记的(CA)15探针和磁珠富集法构建了大珠母贝(Pinctada maxima)微卫星DNA文库,随机挑选1200个菌落,经PCR筛选得到298个候选克隆,成功测序246个,分析获得251个微卫星序列,其中完美型、非完美型和混合型分别占63%、32%和5%。除探针中使用的CA重复外,还得到AT、GT、TC、AG、GC、TAA、CAA、AGG、GATA、GACA、GTGC、CGTC、GACG、CTGT等重复序列。设计引物90对,挑选其中30对合成并筛选出21对能在大珠母贝基因组有效扩增的引物。种群PCR扩增后利用变性聚丙烯酰胺凝胶电泳法进行检测,获得了10个多态位点,共检测出59个等位基因,片段长度范围为133~444 bp。各位点等位基因数2~8个,平均等位基因数5.9个;有效等位基因数为1.342 3~6.000 0,平均为4.124 0;多态性信息含量(CPI)为0.222 5~0.811 8,平均0.7179;期望杂合度(He)为0.259 3~0.847 5,平均0.717 9;观测杂合度(Ho)为0.300 0~0.800 0,平均0.533 3。这些微卫星多态性标记的获得,为进一步开展大珠母贝遗传育种、保护生物学和种群遗传多样性等研究奠定了一定基础。  相似文献   

三种蛏的遗传多样性分析   总被引：4，自引：0，他引：4  

邵艳卿  陆荣茂  董迎辉  柴雪良  肖国强  林志华 《海洋科学》2009,33(10):26-30

应用AFLP技术对浙南地区分布的小荚蛏(Siliqua minimai)、缢蛏(Sinonovacula constricta)和大竹蛏(Solen grandis)3种蛏进行了基因组DNA多态性检测,并对其遗传多样性进行了分析.利用筛选出的5对引物组合,共扩增出781个清晰的位点;小荚蛏、缢蛏和大竹蛏多态位点比例依次为79.22%、84.25%和64.82%,Nei's基因多样性指数分别为0.2971、0.3070和0.2785,Shannon's多样性指数分别为0.4402、0.4575和0.4010,种内平均遗传距离为0.2585、0.2691和0.1838.研究结果表明,这3种蛏的核DNA遗传多样性水平以缢蛏为最丰富,小荚蛏次之,大竹蛏最低;并且3种蛏的共享位点很少,遗传趋异比较明显,说明3种蛏的遗传关系比较远.  相似文献   

Origin of red color of the Lower Siwalik palaeosols: A micromorphological approach     

Seema Singh  B.Parkash  Arun.K.Awasthi 《山地科学学报》2009,6(2):147-154

Palaeosols associated with fluvial of the Siwalik Group are and lacustrine deposits that occur as thick multiple pedocomplexes. The bright red color of the palaeosol beds has been earlier interpreted as a result of hot and arid palaeoclimate. However, as against this view, our investigations of the bright red palaeosol beds of the Lower Siwaliks suggest that the climate was cool and subhumid, instead of hot and arid during the deposition of these beds. Since cold climate is not very conducive to impart red coloration, further research is needed to explain the cause of these red beds. For this, the micromorphological study of soil thin sections was done which showed the presence of features such as dissolution and recrystallisation of quartz, feldspar and mica, compaction, slickensides, presence of calcite spars, subrounded and cracked nature of quartz grains, microfabric, complex patterns of birefringence fabrics, pigmentary ferric oxides, thick cutans and cementation by calcite. These features indicate that diagenesis took place on a large scale in these sediments. The positive Eh and neutral-alkaline pH of soils also suggest that the conditions were favorable for the formation of diagenetic red beds. During burial diagenesis of sediments, the hydroxides of ferromagnesian minerals got converted into ferric oxide minerals （hematite）. During deep burial diagenesis smectite was converted into illite and the preponderance of illite over smectite with increasing depth of burial also indicates the diagenesis of sediments. Thus, the red color of the Lower Siwalik palaeosols seems to be due mainly to the burial diagenesis of sediments and does not appear to be due to the then prevailing climatic condition.  相似文献   

Distribution and origin of hybrid beds in sand-rich submarine fans of the Tanqua depocentre, Karoo Basin, South Africa   总被引：2，自引：1，他引：1  

David M. Hodgson   《Marine and Petroleum Geology》2009,26(10):1940

This study documents the stratigraphic and palaeogeographic distribution of hybrid event beds that comprise both debris-flow (cohesive) and turbidity current (non-cohesive) deposits. This is the first study of such beds in a submarine fan system to combine outcrop and research borehole control, and uses a dataset from the Skoorsteenberg Formation of the Tanqua depocentre in the Karoo Basin, South Africa. Three types of 0.1–1.0 m thick hybrid beds are observed, which have a basal weakly graded fine-grained sandstone turbidite division overlain by a division of variable composition that can comprise 1) poorly sorted carbonaceous-rich material supported by a mud-rich and micaceous sand-matrix; 2) poorly sorted mudstone clasts in a mud-rich sand-silt matrix; or 3) gravel-grade, rounded mudstone clasts in a well sorted (mud-poor) sandstone matrix. These upper divisions are interpreted respectively as: 1) the deposit of a debris-flow most likely derived from shelf-edge collapse; 2) the deposit of a debris flow, most likely developed through flow transformation from turbidity current that eroded a muddy substrate; and 3) from a turbidity current with mudstone clasts transported towards the rear of the flow. All three hybrid bed types are found concentrated at the fringes of lobes that were deposited during fan initiation and growth. The basinward stepping of successive lobes means that the hybrid beds are concentrated at the base of stratigraphic successions in medial and distal fan settings. Hybrid beds are absent in proximal fan positions, and rare and thin in landward-stepping lobes deposited during fan retreat. This distribution is interpreted to reflect the enhanced amounts of erosion and availability of mud along the transport route during early lowstands of sea level. Therefore, hybrid beds can be used to indicate a fan fringe setting, infer lobe stacking patterns, and have a sequence stratigraphic significance.  相似文献