海草床鱼类群落结构的时空变化及其在热带海草床中的育幼     

杜建国  王彦国  PERISTIWADY Teguh  廖建基  MAKATIPU Petrus Christianus  HUWAE Ricardo  鞠培龙  LOH Kar Hoe  陈彬 《海洋学报(英文版)》2018,37(12):63-72

本文以印尼北苏拉威西东部的潟湖为对象，研究了热带海草床鱼类群落的种类组成和时空变化。研究发现当地鱼类的香农-威纳指数在1.57-3.69之间多样性相对较高。在科水平，天竺鲷科的丰度（8.27 ind./（100 m²））和生物量（28.49 g/（100 m²））最高。在物种水平，侧带天竺鲷（Apogon lateralis）的丰度最高，环纹圆天竺鲷（Sphaeramia orbicularis）的生物量最大。对于物种的空间变化，潟湖湖顶、湖中和湖口首先聚类在一起，这可能是由于基质类型引起的。干季和湿季的鱼类种类、丰度和生物量均比转换季高，这可能是由较强的季风造成的，强季风为鱼类提供了更适宜的环境和食物。93.1%的鱼类的最大体长小于它们的性成熟体长，暗示了海草床是很多鱼类的育幼场。因此，保护海草床对渔业和资源的可持续利用至关重要。  相似文献   

鄂尔多斯盆地宜川地区二叠纪孢粉化石组合特征          下载免费PDF全文

高存山 《山东国土资源》2018,34(11)

通过对延长油矿延223井晚古生代孢粉组合研究以及古植被的恢复,探讨了该区晚古生代孢粉植物化石组合的地层学和古气候意义。根据孢粉化石主要属种的时代分布及其在各样品中百分含量的规律性变化,自下而上建立了3个孢粉组合:Gulisporites cochlearius-Laevigatosporites minimus组合、Sinulatisporites-Florinites组合和Lueckeisporites permianus-Platysaccus radialis组合。根据对划分孢粉组合的特征分析,通过与邻区及华北地区晚古生代孢粉组合的对比,探讨了孢粉组合的时代意义。通过孢粉组合,推测了相应时期的古植被类型,并与前人在相同地质时期所建立的大植物化石带进行了对比,分析了各地质时期植被的兴起、发展、繁盛以及衰退绝灭的历史过程,研究区二叠纪植物群属于典型的华夏植物群,反映了一种温暖潮湿的热带雨林气候,二叠纪晚期随着松柏类植物所占比例的增加,气候有变干旱的趋势。  相似文献   

蓟县中、新元古界的成岩作用——源于矿物学的数据     

王河锦  陈梦瑶  安佳丽  王冠玉  晏玉 《地质学报》2021,95(5):1469-1480

本文运用系列黏土矿物学和碳酸盐结构占位的方法研究了蓟县中、新元古界剖面出露的碎屑岩和碳酸盐岩.这些方法包括了伊利石结晶度、绿泥石结晶度、黏土矿物组合、粒度分布、多型、有序度、Mg/Ca离子占位以及地质温压计.结果表明:伊利石结晶度Kübler指数范围为0.37°～1.37°Δ2θ,绿泥石结晶度árkai指数范围为0.31°～2.40°Δ2θ,以及1Md的多型,一致指示本区处于晚期成岩作用影响范围,仅非常有限局部达到了初始变质的状态;黏土矿物组合主要是伊利石、伊蒙混层、绿蒙混层和高岭石;粒度分布范围为8～24 nm,其上界(23～24 nm)达到了NEWMOD计算的理论成岩带/近变质带界限,与结晶度数据一致,也表明了本区处于晚期成岩阶段.白云石有序度的数据表明,本区碳酸盐岩白云石的有序度值范围为0.19～0.99,可分为4个带:甚低级有序带、低级有序带、中级有序带、高级有序带.与川东石炭-二叠系碳酸盐岩相比,中低级有序带有一定的油气前景.本区由西向东,由甚低级有序带变化到高级有序带,白云石有序度升高.估计的成岩作用温度为183～200±20℃,压力为330 MPa,古地热梯度为17～21℃/km.  相似文献   

Holocene environmental evolution recorded by core sediments of Judian Lake in the east of Lubei Plain,Shandong Province          下载免费PDF全文

Zou Chun-Hui  Zhao Qiang  Mao Long-Jiang 《古地理学报》2021,22(6):1209-1220

Judian Lake in the east of Lubei Plain is located in the monsoon area of northern China,which is sensitive to global climate change and provides abundant lake sedimentary data for the study of the past climate and environment evolution in the land-sea interaction area. Based on the sporopollen identification,grain size analysis and AMS¹⁴C dating of core sediments from the drilling hole of the Judian Lake,the evolutional process of climate and environment since 8900 cal a BP in the northern Lubei Plain was discussed. The results show that: 8900-7625cal a BP,the temperature and precipitation increased and the climate changed from cold-dry to warm-wet;7625—6810 cal a BP,the overall climate was becoming cooler and drier;6810—4435cal a BP,the temperature rose and the precipitation increased,showing an overall warm and humid climate in the middle Holocene;4435—3150cal a BP,the climate was generally cold and humid with some low-amplitude fluctuations of cold and warm. During the middle Holocene,there were two obvious cold and dry events in 5450—5280cal a BP and 4160—4090cal a BP,which was consistent with the geological and climatic records in China and even in the world. It may be due to the southward movement of the equatorial convergence zone caused by the change of solar radiation,the change of ocean surface temperature and the feedback of surface vegetation.  相似文献   

Geochemical Stratigraphy and Microvertebrate Assemblage Sequences across the Silurian/Devonian Transition in South China     

ZHAO Wenjin  WANG Nianzhong  ZHU Min  Ulrich MANN  Ulrich HERTEN  Andreas LüCKE 《《地质学报》英文版》2011,85(2):340-353

Carbon isotope (δ13Corg) analyses of non-marine clastic rocks and neritic carbonates and black shales spanning the Silurian/Devonian transition are compared from two richly fossiliferous sequences in Qujing of East Yunnan and Zoige of Sichuan, South China. The two sections, Xishancun and Putonggou sections in South China, reveal positive δ13Corg shifts happening in the Upper Pridoli and Lower Devonian and reaching peak values as heavy as ?25.2‰ (Xishancun) and ?19.9‰ (Putonggou) in the lowermost Lochkovian following the first occurrence of the thelodont Parathelodus and the conodont Icriodus woschmidti woschmidti (only in Putonggou Section and together with Protathyris-Lanceomyonia brachiopod fauna). These results replicate a globally known positive shift in δ13Corg from the uppermost Silurian to the lowermost Devonian. The δ13Corg variations across the Silurian/Devonian Boundary (SDB) at the two sections in South China exhibit a shift in carbon isotopic composition similar to the detailed SDB curves from the borehole Klonk-1 drilled at top of the Klonk Global Standard Stratotype-Section and Point (GSSP) in the Prague Basin, Czech Republic. In addition, four microvertebrate assemblages, including the Liaojiaoshan, Xishancun, Yanglugou and Xiaputonggou assemblages, are recognized from the Silurian/Devonian transition exposed in the Xishancun and Putonggou sections, respectively. The results from both carbon isotope stratigraphy and microvertebrate assemblage sequences suggest that the SDB in South China is located at the base of the Xishancun Formation (between sample QX-20 and sample QX-21) in the Xishancun Section and the lower part of the Xiaputonggou Formation (between sample ZP-09 and sample ZP-10) in the Putonggou Section. The isotopic trend for organic carbon together with the changes of microvertebrate remains across the SDB can offer an approach to a potential correlation of the SDB from different sedimentary facies, which help to correlate the marine with non-marine deposits.  相似文献   

甘肃省临夏盆地更新世早期湖泊沉积孢粉记录的古气候演化          下载免费PDF全文

董铭  方小敏  史正涛  明庆忠  苏怀 《第四纪研究》2011,31(1):104-111

根据孢粉组合特征,将临夏盆地早更新统东山组(2.50-1.76Ma)的孢粉划分为3个孢粉带(含6个亚带),即3个植被、气候阶段,第一阶段(2.50-1.91Ma,带Ⅰ),植被类型是以柏科、榆属和禾本科为优势种的温带森林,气候表现为温凉稍干,并有逐渐干旱化的趋势.第二阶段(1.91-1.80Ma,带Ⅱ)是以云杉属、榆属和...  相似文献   

唐山地区晚更新世以来的孢粉组合特征及其与邻区的对比     

李玉嵩  陈建强  赵硕  王海英  李欣 《地球学报》2011,32(2):178-188

通过对唐山市复兴路十中旧址钻孔更新统上部和全新统部分的60 m岩芯的沉积物及92件孢粉样品的分析, 建立了4个组合带, 总结了唐山地区晚更新世以来的植被演替和气候变化: (1)孢粉带Ⅰ, 以针阔混交林-草原为主, 气候温暖湿润; (2)孢粉带Ⅱ, 以疏林草原为主, 气候寒冷干旱, 为晚更新世以来环境最为恶劣的时期; (3)孢粉带Ⅲa, 植被为针阔混交林-草原, 气候温暖湿润; (4)孢粉带Ⅲb, 发育暗针叶林-草原, 气候寒冷湿润; (5)孢粉带Ⅲc, 植被为疏林草原, 气候寒冷略干; (6)孢粉带Ⅳ, 发育针阔混交森林, 气候温暖湿润, 为晚更新世以来水热条件最佳的时期。通过与邻区及全球冰芯、深海沉积研究成果的对比分析, 探讨了华北平原晚更新世以来的气候变化特点: MIS3的温湿条件显著优于MIS2和MIS4, 达到间冰期气候, 与MIS5相似, 局部地区甚至超过MIS1; MIS2不是一个持续干冷的过程, 而是一个由湿冷逐渐转向干冷的过程。此成果对探讨华北平原第四纪地层划分、对比和气候演化提供了科学依据。  相似文献   

宁夏银川水洞沟遗址2号点晚更新世晚期孢粉记录的古环境     

刘德成  高星  王旭龙  张淑芹  裴树文  陈福友 《古地理学报》2011,13(4):467-472

宁夏银川水洞沟遗址2号点剖面孢粉分析结果表明:该地区在晚更新世晚期孢粉组合以草本植物花粉占绝对优势,有Chenopodiaceae、Artemisia、Zygophyllum、Ranunculaceae和少量的Euonymus、Ephedra和Nitraria等,木本植物花粉次之,有Pinus、Picea、Abies、...  相似文献   

Spatial variation patterns of subtidal seaweed assemblages along a subtropical oceanic archipelago: Thermal gradient vs herbivore pressure     

Carlos Sangil  Marta Sansón 《Estuarine, Coastal and Shelf Science》2011,94(4):322-333

The structure and composition of subtidal rocky seaweed assemblages were studied at 69 sites on the Canary Islands (northeastern Atlantic). This group of islands are situated at the southern boundary of the warm temperate region and adjacent to the cold waters from the northwest African coastal upwelling, which creates a difference of almost 2 °C in surface seawater temperature from the eastern to the western islands. This thermal variation allows an examination of the transition between the warm temperate and the tropical regions along this longitudinal gradient together with the hypothesised Fucales-dominated assemblages towards the eastern islands in contrast to the Dictyotales-dominated assemblages towards the western ones. Environmental and biological parameters were considered in order to investigate which were the main factors explaining spatial variation along the gradient in a multi-scaled approach. Although seventy-nine macroalgae were identified, 87.63% of the total mean cover was due to six taxa (Lobophora variegata, nongeniculate corallines, Canistrocarpus cervicornis, Jania adhaerens, Cystoseira abies-marina and Pseudolithoderma adriaticum). At a large scale, sea urchin density explained the highest variation in seaweed assemblages (26.94%), and its pattern of distribution across the islands. The expected pattern of distribution according to the upwelling distance only occurred in restricted areas of the Canarian Archipelago in absence of herbivore pressure and habitat degradation. Spatial variations within islands (medium scale) were mainly related to wave exposure, while at a small scale these were mostly due to the degree of sedimentation.  相似文献   

云南全新世气候变化研究综述   总被引：1，自引：0，他引：1  

杨冬琴  刘波 《云南地理环境研究》2011,23(4):106-111

大尺度时间段气候的研究成果,特别是最年轻的地质时期全新世(11 500年前至今)的气候特点是研究现在气候变化的重要依据。通过对比云南不同地点的湖泊沉积、岩溶化学沉积物、洞穴沉积物等例证研究,总的来说,云南全新世气候整体演化与全球气候变化具有一致性,在地理位置、季风等因素的影响下又具有独特的气候特征。  相似文献