首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 0 毫秒
1.
The Red Beds of Nandian consists mainly of red mud stone, marlite, quartzitic sand- stanc, Sabulous psephyte and fine psephyte. Predecessor divided them into three formations referring to Upper Triassic-Jurassic. The marlite in Upper Formation of the Red Beds are rich in fossil Sporo-pollen. The fossil spores and pollen contain 17 genera and 15 species, including 3 new species and 2 new combinations. The Sporo-pollen assemblage is characterized by the absolut predominance of the pollen of gymnospcrms (84.8%) compared with the spores of pteridophyta (15.2%), The pollen are specially characterized by the abundance of Classeopollis Pfiug (75.3%) with a certain amount of Psophosphaera (4.5%), Monosulites (2.4%) and a minority of Pinuspollenites (0.6%). The spores grains are characterized by the abundance of Cyathidites (4.1%), and also by presence of Calamospora (2.1%), Reticulatisporitcs (2.4%), Indeterminable form (1.2%), and rare Schizaeisporites (0.3%). Based on the sporo-pollen assemblage of Upper Jurrassic of the Eurasia continent is characterized by the absolute abundance of Classpollis Pflug (>50% of the total number), the Upper Formation oi the Red Beds of Nandian may be referred to Upper Jurassic age. The climate of the Nandian region in the Late Jurassic period is supposed to be as arid as that of Africa at the present time. Bundary of the eastern termination of southern part of the Eurasia continent in- ferred by Vakhrameev (1970) should be complemented.  相似文献   

2.
Forty-seven species of fossil pollens and spores referred to 33 genera extracted from the crude oil samples collected from the Yecheng Seg of the Talimu Basin in Xinjiang were observed. Based on the investigation of the characteristics of the petroleum sporo-pollen assemblage, the problem on petroleum source of this oil-bearing region is discussed. The principle and method to judge source rock from petroleum sporo-pollen assemblage are specially explained in this paper. The petroleum sporo-pollen assemblage of the Neogene reservoir of the Yecheng Seg consists of Deltoidospora perpusila, Deltoidospora gradata, Cyathidites australis, Cyathidites minor, Biretisporites potoniaei, Dictyophyllidites harrisii, Dictyophyllum rugosum, Cibotiumspora paradoxa, Gleicheniidites senonicus, Gleicheniidites rousei, Undula- tisporites concave, Lycopodiumsporites sp., Osmundacidites wellmanii, Leptolepidites major, Apiculatisporis ovalis, Bennettiteaepollenites lucifer, Cycadopites typicus, Cyeadopites nitidus, Cycadopites minimus, Cycadopites carpentieri, Cycadopites follicularis, Chasmatosporites elegans, Classopollis classoides, Classopollis annulatus, Podocarpidites multesimus, Podocarpidites major, Parvisaccites enigmatus, Quadraeeulina limbata, Caytonipollenites pallidus, PteruchipoUenites thomasii, Alisporites grandis, Alisporites bilateralis, AbietineaepoUenites microalatus, Abietineaepollenites minimus, Pinuspollenites sp., Piceaepollenites sp., Cedripites st)., Ephedripites sp., Eucommiidites troedssonii, Magnolipollis neogenicus, Quercoidites microhenrici, Chenopodipollis multiplex, Artemisiae-pollenites sellularis, etc . This is a typical composite type of petroleum sporo-pollen assemblage, which eomprises the Jurassic species, the Cretaceous species, the Eogene species and the Neogene species of spores an, d pollen. In accordance with the characteristics of the above mentioned petroleum sporopollen assemblage, the source rock of the Yecheng Seg is considered to be Jurassic Period in age, and the black shales and mudstones of the Middle Jurassic Yangye-Taerga Formation are judged to be the most favorable source rocks in the region.  相似文献   

3.
An Early Pliocene pollen assemblage from Huang-Hua is situated in the east part of Hebei Plain. The pollen assemblage which has been studied is a basis of considering the plant development of that period. The pollen assemblage shows an aspect of deciduous forest appearance and a concept of "warm-temperate" climate then. The flora is dominated by Ulmus, Quercus and Carya, and some temperate elements such as Abies, Picea, Pinus, Salix, Betula, Carpinus, Juglans, Acer and Tilia are the obvious generally. Except Carya, the subtropical elements: Podocarpus, Keteleeria, Tsuga, Pterocarya, Liquidambar, Hamamelis, Fothergilla and Xanthoxylum are the conspicuous elements in the assemblage, too. However herbs espicially Compositae become more abundant. It is clear that some tropical and subtropical elements such as Proteaceae, Nyssaceae Myrtaceae, Sympolocaceae etc. which were prevalent in early Tertiary are entirely lacking. Owing to the lack of Taxodiaceae instead by Pinaeeae and there are some genus of Composite and Tricoporite rugulates in the assemblage. It is more likely to be early Pliocene period. The assemblage expressed a transitional stage of plants from subtropical to tem- perate zones.  相似文献   

4.
5.
陕西彬县地区中侏罗世延安组孢粉植物群及其意义   总被引:7,自引:0,他引:7  
报道了采自陕西彬县地区中侏罗世延安组的孢粉化石60属,83种。经研究表明,陕西彬县地区延安组的孢粉组合是以裸子植物花粉为主,蕨类植物孢子次之。银杏、苏铁类和松柏类花粉在组合中占优势;桫椤科孢子在蕨类中具有较高的含量。根据孢粉组合特征及其对比,延安组的时代应属中侏罗世早期。陕西彬县地区当时的植被是以银杏、苏铁类和松柏类等乔木为主,并伴有桫椤科为主体的树蕨植物及草本植物,古气候应属大陆性亚热带气候。  相似文献   

6.
Twenty-six species (or forms) of fossil pollen and spores referred to 24 genera extracted from the crude oil samples collected from the Yumen oil-bearing region in West Gansu are observed and the definition of the petroleum sporo-pollen assemblage is given by the authors. On the basis of palynological investigation, the oil source rock of this oil-bearing region is tentatively discussed in this paper. The fossil pollen and spores found from the Tertiary petroleum in this region may be divided into two groups, because they are extremely different in fossilized state. The group of spores and pollen with higher fossilized state is mainly consisted of Schizaeoisporites zizyphinus, Gibotiumspora paradoxa, Monosulcites minimus and Bennettiteaepollenites sp. The other group comprises Pinus, Picea, Ephedra, Potamogeton, Lilium, Ulmus, Chenopodium, Nymphaea, Eutrema, Lens, Nitraria, Tamarix, Achillea, Artemisia, Solidago, Bidens, Graminidites, Cypheraceaepollis, etc. The above mentioned petroleum sporo-pollen assemblage of the tertiary oil reservoir rock is a gathering of fossil pollen and spores brought from the Lower Cretaceous deposits and the tertiary deposits respectively. The appearance of the Early Cretaceous pollen and spores bearing in the black shales of the Lower Xinminbu Formation in the tertiary petroleum may be considered to be a result of petroleum migration. And it reflects that the oil source rock might belong to Early Cretaceous Series. The fossil pollen and spores extracted from the Early Cretaceous petroleum in this region contain merely Schizaeoisporites zizyphinus, Monosulcites minimus, Bennettiteaepollenites sp., Psophosphaera, etc. The tertiary pollen and spores are completely absent there. So it indicates that both the oil source rock and the oil reservoir rock should belong to the fossil-bearing Lower Xinminbu Formation. In addition, there are some pollen of Monosulcites and Psophosphaera in the petroleum reserved in the fissures of the Silurian metamorphic rock. They are also probably brought from the Lower Xinminbu Formation by oil and gas in the process of their migration. In any case, judging from the pollen and spores found from the crude oil, the oil source rock of this oil-bearing region is deduced to be the black shales of the Lower Xinminbu Formation referred to as Early Cretaceous Epoch.  相似文献   

7.
丹江口库区贾湾1号旧石器地点位于河南省淅川县盛湾镇贾湾村,埋藏于丹江右岸第三级基座阶地前缘的红色黏土层中。2011年4-5月对该地点进行抢救性发掘,揭露面积1000m2,共获得750件石制品(发掘527件,采集223件)。石制品组合包括石核类、修理类、废片类和石锤等,以废片类为主体。石制品以阶地底部砾石为原料,以小型和中型者居多;剥片主要采用硬锤锤击法;石器主要以石片为毛坯,采用锤击法多在石片远端或两侧进行单向加工,刮削器是主要类型。石器工业面貌属于以石核和石片为主体的技术类型(模式1)。地貌、地层及石制品组合特征显示该地点可能形成于晚更新世早期。  相似文献   

8.
云南抚仙湖沉水植物分布及群落结构特征   总被引:14,自引:0,他引:14  
2005年6~7月对抚仙湖沉水植物进行了调查。共采集到沉水植物12种。沉水植物在抚仙湖沿岸浅水区均有不同程度的分布,主要分布在北岸、南岸、河口以及湖湾。分布区内平均水深4.27m,平均透明度2.96m。优势种为黑藻、穗状狐尾藻、篦齿眼子菜、金鱼藻和苦草,其优势度分别为59.08%、54.47%、54.26%、48.71%和48.30%,占群落总优势度的65.19%。根据优势种及组成特征,可将沉水植物群落分为11个类型。全湖沉水植物分布区面积318.8hm^2,资源量19502.79t,平均生物量6118g/m^2。2005年与1980年前后和2003年的调查结果相比,抚仙湖沉水植物、生物量和分布范围显著增加。  相似文献   

9.
陕西水鸟的地理分布   总被引:3,自引:0,他引:3  
按国家林业局2003年<全国湿地资源调查简报>中发布的"水鸟名录"对陕西省分布的水鸟进行了统计.根据陕西省动物地理区划,分别统计了4个地理省8个地理州中水鸟的物种组成,并计算了省间和州间的群落相似性指数.结果 表明:陕西省共有水鸟104种,其中留鸟20种、夏候鸟32种、冬候鸟22种、旅鸟30种.河流众多的关中平原省的渭河谷地平原州的水鸟种类最多,有85种,水鸟最少的是干旱的黄土高原省的南部黄土塬土石山地梢林州,仅有23种;群落相似性指数最高的是相邻的黄土塬土石山地梢林州和渭北台塬州.群落相似性最低的是距离最远的长城风沙州和大巴山地森林州.最北部的长城风沙州的夏候鸟最多,中部的渭河平原州冬候鸟最多,南部的汉江沿岸浅山谷地盆地州的留鸟最多.  相似文献   

10.
陕西省发现刘氏链蛇   总被引:1,自引:0,他引:1  
  相似文献   

11.
陕北黄土丘陵区撂荒群落排序及演替   总被引:1,自引:0,他引:1  
杜峰  徐学选  张兴昌  邵明安  梁宗锁  山仑 《生态学报》2008,28(11):5418-5427
根据2003和2005年分别对36和34块撂荒群落及其生境的调查结果,分析了撂荒群落的排序演替规律、演替速度及演替趋同或趋异性。结果表明:(1)对陕北黄土丘陵区撂荒群落影响较大的因子主要有撂荒年限、海拔、土壤水分含量及变异量、有机质、全氮和速效氮、速效磷等,而坡度、坡向等对撂荒群落分布及动态影响较小;(2)排序图也反映了撂荒演替过程中主要环境因子的变化,即随着撂荒年限的增加,土壤水分含量减少,变异量增加。土壤养分方面,除速效磷呈减少趋势外,土壤有机质,全N、P、K,速效N、K都有增加的趋势;(3)农田撂荒后,群落演替速度有先降低后增大的趋势。提出一个关于撂荒演替速度的分阶段循环往复式的理论模型,认为植被演替从总体上讲是逐渐变慢的,可根据生长、生活型和优势植物种等分为几个阶段,每个阶段初期演替速度较快,以后逐渐变慢达到阶段稳定状态。之后,随着下一阶段主要植物的入侵,阶段稳定状态被打破,演替进入下一阶段。(4)演替趋同、趋异性方面,两年的结果不一致,与样地选择有关。  相似文献   

12.
13.

Background

The main objective was to investigate the burden of birth defects among alive infants and explore the impact of maternal lifestyle during pregnancy on the burden of birth defects in Northwest China.

Methods

A stratified multi-stage sampling method was used to study infants born during 2010–2013 (and their mothers) in Shaanxi province of Northwest China. Socio-demographic information was collected using a structured questionnaire, and medical records from the local hospitals were used to determine the final diagnosis of birth defects. Poisson regression analysis was performed to assess the association between maternal lifestyles during pregnancy and the burden of birth defects, while adjusting for potential confounders.

Results

We sampled 29098 infants, of whom 629 (i.e. 216.17 per 10000) were observed to have congenital defects. Cardiovascular system defects (77.32 per 10000) were found to be the most common. Mothers who had ever consumed alcohol during pregnancy were found to have infants with a higher prevalence of some categories of birth defects, including nervous system (Prevalence Rate Ratio, PRR:14.67, 95%CI:1.94, 110.92), cardiovascular system (PRR:3.22, 95%CI: 1.02, 10.16) and oral clefts (PRR:9.02, 95%CI: 2.08, 39.10) in contrast to infants of mothers without any alcohol consumption. Maternal passive smoking during pregnancy lead to the increased burden of malformations of eye, ear, face and neck (PRR:1.95, 95%CI:1.15, 3.33), cardiovascular system (PRR:1.70, 95%CI: 1.25, 2.31) and respiratory system (PRR:9.94, 95%CI: 2.37, 41.76) in their newborns. Further, tea or coffee consumption during pregnancy was positively correlated with the burden of specific birth defects, such as cardiovascular system (PRR: 2.44, 95%CI: 1.33, 4.46) and genital organs (PRR:14.72, 95%CI: 1.87, 116.11) among infants.

Conclusions

The prevalence of birth defects was high in Shaanxi province of Northwest China. The unhealthy lifestyles of mothers during pregnancy may increase the prevalence of congenital malformations. These findings in future may have some important implications for prevention of birth defects in Northwest China.  相似文献   

14.
《Plains anthropologist》2013,58(65):228-230
Abstract

A cache of four clay figurines from a large rockshelter in the Lower Pecos region in Val Verde County, Texas, is described. A tentative date range of 2000 to 1200 B.C., which is within the Middle Archaic period of the local chronology, is proposed for the cache on the basis of artifact associations.  相似文献   

15.
为了扩大朱鹮Nipponia nippon的种群数量和分布区,自2013年开始在秦岭以北的陕西省铜川市开展了朱鹮的再引入工作。通过彩色数字环观察、无线电遥测和卫星跟踪,对再引入的62只朱鹮在2014—2015年2个繁殖季节的活动状况和繁殖状况进行了监测。2年共记录到8个巢,窝卵数为2.5枚±0.9枚,繁殖成功率达80%,高于野生朱鹮。主要营巢树种为加拿大杨Populus canadensis(n=5)和刺槐Robinia pseudoacacia(n=2),分布在距主要觅食河流沮河300 m以内,巢址特征与野生朱鹮相似。2只卫星跟踪朱鹮的繁殖期活动区面积分别为262.4 km2和20.1 km2,远高于野生朱鹮。铜川单一的河流觅食环境是限制朱鹮种群繁育壮大的主要因素,采取适宜的湿地恢复和繁殖期投食措施可有效改善这一状况。  相似文献   

16.
通过2006年3月至2007年3月对陕西延安黄龙山褐马鸡自然保护区鸟类资源调查,结合历史文献,确认保护区有鸟类14目32科139种.其中国家Ⅰ级保护鸟类4种,Ⅱ级保护鸟类18种.保护区鸟类以留鸟和夏候鸟为主,有留鸟57种,夏候鸟35种,而冬候鸟、旅鸟分别只有19种和28种.列入CITES的共有22种,IUCN的有4种,中国物种红色名录有7种.鸟类区系组成为:古北界种类有39种,东洋界种类21种,广布种32种.以古北界种类占优势,且兼有丰富的东洋界种类.同时,具蒙新区、青藏区和华北区特点.  相似文献   

17.
晋陕宁黄土丘陵区生态修复与农林牧业持续发展仿真研究   总被引:1,自引:0,他引:1  
晋陕宁黄土丘陵区土壤侵蚀严重,生态环境脆弱,不合理利用土地是其主要原因,生态修复与环境重建是该区生态与经济持续发展的重要战略措施。应用系统动力学(System Dynamic,简称SD)和“反馈控制(Feedback control)理论建立了该区生态修复和环境重建的SD模型,它分为人口、农业、林业、牧业、农村经济、土壤侵蚀和生态环境6个模块,仿真时间1990~2080年,步长1a。经检验该SD模型的有效性为93.5%,可用于未来仿真预测。根据该区的生态环境特点和农牧业发展现状,选择生态环境恢复重建的3种典型模式——同步发展模式(A模式)、逐步调整模式(B模式)和现状发展模式(C模式)进行仿真研究,预测3种模式2000~2080年的土壤侵蚀、土地利用的发展动态以及农林牧业和生态环境演化趋势。仿真结果表明:土地利用与农、林、牧业持续发展密切相关,坡耕地和草场退化是制约农林牧业发展的主要因素。合理调整土地利用结构和加速治理侵蚀,可促进生态环境逐步恢复和农林牧业持续发展。同步发展模式(A模式)是该区生态修复和环境重建的3个仿真模式中的最优策略,它可促进农林牧协调发展和生态一经济趋向良性循环,并提出该区生态修复与环境重建的对策措施。该SD模型结构合理,运行功能良好,能较真实的模拟具有多变量、非线性变量的复杂生态系统的动态行为,为生态修复研究提供一种有效工具。  相似文献   

18.
2012~2013年每年的4~7月,在陕西神木县红碱淖(39°04'21″~39°04'43″N,109°53'12″~109°53'40″E)对白喉林莺(Sylvia curruca)的繁殖生态进行了研究。结果表明,白喉林莺4月末迁来繁殖,5月初开始营巢于油蒿(Artemisia ordosia)、臭柏(Sabina vulgaris)和沙棘(Hippophae rhamnoides)灌丛中,巢口向上呈深杯状,巢由柳絮、枯枝和干草编织而成。对33个巢的参数进行了测量,巢外径(9.62±0.227)cm,巢内径(5.21±0.084)cm,巢深(5.05±0.160)cm,巢高(9.03±0.185)cm,巢距地面高度(24.91±1.084)cm,巢约位于植株高度的1/3处(由下而上)。营巢成功率为77.1%(n=35),窝卵数4~5枚(n=27),卵重(7.49±0.021)g,卵长径(17.27±0.057)mm,卵短径(12.86±0.080)mm(n=130)。孵化期为11~13 d,孵化率为93.1%,雏鸟出飞为90.9%。雏鸟的形态参数生长符合Logistic曲线方程拟合。植被高度、植被盖度和单株植物冠径是制约白喉林莺巢址选择的主要因素,同时恶劣天气和人为干扰是影响繁殖成效的主要原因。  相似文献   

19.
The present study examined the prevalence and genotypes of Cryptosporidium andersoni in cattle in Shaanxi province, China. A total of 2071 fecal samples (847 from Qinchuan cattle and 1224 from dairy cattle) were examined for the presence of Cryptosporidium oocysts, and 70 samples (3.4%) were C. andersoni-positive and those positive samples were identified by PCR amplification of the small subunit ribosomal RNA (SSU rRNA) and the Cryptosporidium oocyst wall protein (COWP) genes. C. andersoni was the only species found in the examined cattle in this province. Fifty-seven C. andersoni isolates were characterized into 5 MLST subtypes using multilocus sequence typing analysis, including a new subtype in the native beef breed Qinchuan cattle. All of these C. andersoni isolates presented a clonal genetic structure. These findings provide new insights into the genetic structure of C. andersoni isolates in Shaanxi province and basic data of Cryptosporidium prevalence status, which in turn have implications for controlling cryptosporidiosis in this province.  相似文献   

20.
2011年8月22日,在陕西省宝鸡市太白县的铁龙洞(33°43'38.8″N,107°26'37.9″E,海拔1 250 m)获得2号蝙蝠标本,雄性,体型较大,前臂长约58 mm,后足长几与胫长相当,约20 mm,经鉴定为大足鼠耳蝠(Myotis ricketti),属陕西省翼手类新纪录,标本保存于陕西省动物研究所标本室。本文对该蝙蝠标本的特征和相关测量数据进行了报道,并对其分布和保护现状进行了探讨。  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号