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1.
Based on archaeological excavations, 217 samples were collected from the Luotuodun Site. Of them 63 samples from the section plane of the site layer were used for identification analysis of foraminifera, plant debris and seed fossils, and four samples were used for 14C dating and relevant analysis. Through many kinds of experiments, we have drawn some conclusions. Firstly, benthic foraminifera, such as Ammonia compressiuscula and Ammonia cff. sobrina, are found in the 10th layer, indicating that between 7500 and 5400 BC, i.e. before the emergence of the Majiabang Culture, Luotuodun Site and its nearby regions had ever experienced a marine transgression event. Secondly, we have found 450 plant fossils in this site, such as Polygonum sp., Scripus sp., Najas sp., Physalis sp., which indicated lacustrine or swamp environment.  相似文献   

2.
江苏宜兴骆驼墩遗址地层7500~5400BC的海侵事件记录   总被引:1,自引:0,他引:1  
李兰  朱诚  林留根  赵泉鸿  史恭乐  朱寒冰 《地理学报》2008,63(11):1189-1197
在考古发掘基础上,野外共采集样品217个,对遗址地层剖面中63个样品进行了有孔虫、植物碎屑及种子化石等的鉴定分析,对4个地层相关样品进行了14C测年及相关分析。在第10层的泥炭层中发现底栖有孔虫2种1属,即压扁卷转虫(Ammonia compressiuscula)和近亲卷转虫相似种(Ammonia cff.sobrina),表明全新世以来骆驼墩遗址及其附近区域在马家浜文化出现之前的7500-5400BC之间曾经历过海侵事件;共发现植物化石9种450颗,鉴定结果共统计出4(科)属,即Polygonum sp.(蓼属未定种)、Scirpus sp.(藨草属未定种)、Najas sp.(茨藻属未定种)、Physalis sp.(酸浆属未定种),多属湖泊、沼泽等水生环境。  相似文献   

3.
朱诚  张强  张芸  张之恒  沈明洁 《地理科学》2003,23(6):705-712
通过长江三角洲长江以北地区高邮龙虬庄和海安青墩两个新石器时代考古遗址剖面粒度、磁化率、孢粉以及年代学测定,较为全面地分析了该区全新世以来生态环境变化与人类文明兴衰的相互关系,研究结果表明:在有人类活动以前,该区距离海洋较远,但受海面变化影响强烈。此后,气候向暖湿方向发展,7000—6000间的大西洋温暖湿润气候以及3700aB.P.左右期间,该区气候适宜,人类文明在这样的适宜气侯条件下得到长足发展。值得注意的是,海安青墩遗址剖面中出现厚达1m多的自然沉积地层,粒度分析以及孢粉分析表明,这一自然沉积地层是4000aB.P.以来的海侵事件所致,正是这次海侵事件,使研究区人类文明得以衰落。  相似文献   

4.
We have explored the contemporary spatial relationship between aquatic vegetation and surficial macrofossil and pollen remains in a small, shallow, English lake. A detailed point-based (n = 87) underwater vegetation survey was undertaken in the middle of the plant-growing season in July 2000. Then following plant die-back in November 2000, surface sediment samples (upper 1.5 cm) were collected from 30 of these plant survey points and analysed for plant macro-remains (all 30 samples), and pollen (4 evenly spaced samples). All data were stored as separate layers in a geographical information system and spatial relationships between the aquatic vegetation and plant remains were explored. In contrast to pollen types, plant macrofossils were not evenly dispersed across all parts of the lake and, with the exception of Chara oospores, higher concentrations of remains (particularly for Potamogeton) were found close to areas of source-plant dominance. The spatial pattern of macrophyte–macrofossil relationships revealed that vegetative remains (particularly leaf fragments) were probably deposited at source, whereas seeds were recovered close to the shore suggesting slightly wider dispersal. Overall, however, macro-remains best represented local ‘patch-scale’ vegetation within 20–30 m of the core site. The macro-remains effectively recorded the dominant plants in the lake with 63% of samples containing a combination of remains of Chara, Elodea, and Potamogeton. However, relationships between macrophytes and fossils were complex. Some species were significantly over-represented by macrofossils (e.g., Chara spp., Nitella flexilis agg., and Zannichellia palustris), while others were either under-represented (e.g., Potamogeton spp.), or not represented at all (e.g., Lemna trisulca). Pollen represented macrophyte diversity poorly, but some taxa were found (e.g., Myriophyllum spicatum, Ceratophyllum demersum) that were not recorded by macro-remains. We conclude that macrofossil analysis may be very usefully employed to determine the dominant taxa in past aquatic plant communities of shallow, productive lakes and that the addition of pollen analysis provides further information on former species richness.  相似文献   

5.
Charophyte (Charales, green macroscopic algae) assemblages found in Quaternary shoreline sediments from Salina del Bebedero, Argentina, are described in detail, illustrated, and statistically analysed. Fossil gyrogonites, Late Pleistocene and Holocene in age, of Chara cf. hispida var. major (Hartman) Wood, Chara halina García, Chara hornemannii Wallmann, Chara bulbillifera (Donterberg) García, Lamprothamnium haesseliae Donterberg and Lamprothamnium succinctum (Braun ex Ascherson) Wood were identified. A comparison with extant charophyte species of similar ecological requirements allowed for an accurate systematical determination and provided useful data for complementary palaeoecological and palaeobiogeographical approaches. On this basis, a reconstruction of palaeo-salinities for the Salina del Bebedero lake, represented by eleven palaeo-beaches, is proposed. Also the associations of charophytes with the ostracods Cyprideis sp., Limnocythere sp., Pampacythere sp., Cypridopsis sp., Darwinula sp., Ilyocypris gibba (Randohr) Brady and Norman, and the foraminifers Ammonia sp., Elphidium gunteri Cole, Quinqueloculina sp., and one species of Discorbacea are analysed, since they are present in both the fossil and modern environments.  相似文献   

6.
刘清泗 《极地研究》1990,2(3):39-45
南极乔治王岛菲尔德斯半岛化石山植物群的发现是研究该地区新生代地质历史的一件大事。通过层位对比、化石特征、植物群组合面貌的研究,认为该植物层的时代为始新世末期至渐新世早、中期,当时为温暖偏干的温带或亚热带疏林环境。  相似文献   

7.
塔里木河中游植物群落与环境因子的关系   总被引:40,自引:2,他引:40  
应用数量分类和排序方法,对新疆塔里木河中游地区植被进行了多元统计分析。结果表明,该地区共有植物23种,隶属于11科21属。其中,多数植物种类在样方中的出现频次较低,说明该地区植物物种丰富度较低。TWINSPAN结果表明,该地区3个断面19个样地可分为3个主要类型,与实际调查结果一致。CCA排序结果同TWINSPAN分类结果基本一致,反映出植物群落分布格局的一般规律及其随环境因子梯度变化的趋势。分析了不同环境因子间的关系,并从定量的角度,以CCA排序图直观地揭示了决定塔里木河中游地区植物群落分布的环境因子主要是地下水位和土壤含水量,其回归模型分别为:X1=-9.5991L 100.86(R^2=0.6459);X2=1.65W 43.011(R^2=0.7646)。  相似文献   

8.
段威武  曹流 《极地研究》1998,10(2):29-35
根据乔治王岛海军湾亨内克角群上部凝灰质砂泥岩夹层中的孢粉化石组合特征,讨论其时代归属和沉积环境。研究表明亨内克角群上部火山沉积岩中孢粉化石共40余种,主要成分为冈瓦纳早第三纪群落,属Weddelian生物地理区,Nothofagidites为代表分子,其中N.cf.saraensis和N.cf.flemingi的存在以及Proteaciditesspp.的缺失,提示含化石地层时代可能属渐新世,沉积环境为近中低山区的湖沼环境,气候温暖潮湿。  相似文献   

9.
根据西湖柱状岩芯样品中藻类化石的分布与含量变化,推测本区在3600年前仍为冰川覆盖;距今3600~3000年前为冰缘浅湖期;3000~1200年前湖水稳定,气候环境相对较好;距今1200年至现代气候略有波动。  相似文献   

10.
2008年,重庆穿洞遗址发掘出一具保存较好的晚更新世大马蹄蝠(Hipposideros armiger)化石,这是中国发现的第5个大马蹄蝠化石地点,同时,也是迄今为止所发现保存最为完整的标本。对该地点化石材料观测显示:大马蹄蝠在与其他翼手目标本进行形态对比时,可以根据其个体大小、颅骨形状及齿式特征等进行多项有效鉴别。在大马蹄蝠演化方面,从化石材料上观察,更新世晚期大马蹄蝠桡骨长度与现生标本基本一致,这反映出大马蹄蝠在更新世晚期其飞翔能力与现生标本相似(桡骨长度增大,这是翼手目与一般哺乳动物相比在演化方面的特化现象)。穿洞大马蹄蝠化石的发现,对研究长江三峡地区第四纪古环境具有重要意义。它证明了更新世晚期时三峡地区有温暖湿润的气候和繁茂的森林植被,并且分布有为翼手目提供居址栖息的大型岩溶洞穴;晚更新世时期,出现于中国其他地区的冰期气候等恶劣环境现象,未曾对长江三峡地区动、植物生存环境造成影响。  相似文献   

11.
Twenty-seven surface samples were collected from the Kjelst Enge salt marsh in Ho Bugt, Jutland, to investigate the potential use of salt-marsh foraminifera as sea-level indicators in Holocene intertidal deposits. Previous work from many coastlines around the world has shown that the vertical distribution of salt-marsh foraminifera is strongly controlled by the duration of tidal flooding (or height relative to tide level). Concentrations of foraminifera in Kjelst Enge salt marsh are low, especially in the high marsh, but a strong correlation was found between relative abundances of foraminiferal species and tidal elevation for 16 samples containing more than 30 specimens per 5 cc of sediment (r2 = 0.80, root mean square error = 0.16 m). Sediment pH also has a strong influence on the distribution of the foraminifera, but salinity appears to be insignificant.  相似文献   

12.
Fossil diatoms in the Valsequillo area are important in supplying adequate paleoecological evidence for the in situ deposition (in the absence of strong water currents necessary for the displacement and redeposition) of artifacts as large as those at the Hueyatlaco Archaeological Site. The paleoecology of lacustrine diatom-bearing samples from four nearby localities in the Valsequillo region all correlated with numerous diatomaceous samples from the Hueyatlaco Site (Puebla, Mexico) and indicate an autochthonous deposition of the artifacts at that site. This correlative evidence is consistent with a deposition in Sangamonian to Illinoian time and is based on the relationships of percentages of taxa in categories of the current, pH, and halobian spectra in six lines of correlation of samples between the Hueyatlaco Site and the four localities.  相似文献   

13.
A Holocene ecological succession was documented using palynological, foraminiferal, and molluscan faunas sampled from an excavated trench on the margin of Bell River Bay, Lake Winnipegosis, Manitoba. The palynological data record the known gradually isostatically-induced shift from aquatic to terrestrial conditions at the site, and clearly delineates the Holocene Hypsithermal maximal warm interval (commencing here about 5500 years BP). Concurrent with this warming the site became occupied by the extinct salt tolerant gastropod Marstonia gelida and the marine foraminifer Cribroelphidium gunteri by at least 5430 years BP. Water fowl-assisted colonization of non-marine habitats by foraminifera has previously been suggested as a dispersal mechanism for other non-marine foraminiferal occurrences. However, as this relatively warm-water foraminifer (presently found as far north as Cape Cod, MA on the Atlantic USA coast, and Vancouver, BC on the Canadian Pacific coast but also found in Canadian Maritime provinces during the Hypsithermal) did not inhabit the area either prior to or following the Hypsithermal warm interval, this occurrence indicates the efficiency with which foraminifera can utilize non-selective avian transport to colonize new non-marine and marine habitats. It may be that only a few years were required for colonization of the site to occur (2000–3000 km distant from native populations); this suggests that avian transport is a much more important foraminiferal dispersal mechanism than previously realized. The appearance of foraminifera at this site may also constrain models designed to determine the time required for hydraulically injected glacial freshwater to be flushed from normally brine producing aquifers in the region.  相似文献   

14.
渤海湾北岸表层沉积中的有孔虫群及其生态环境   总被引:2,自引:0,他引:2  
我们对渤海湾北岸177个表层沉积物样品进行了有孔虫分析。经鉴定,未发现浮游有孔虫,底栖有孔虫共计82种,其中包括一新种Jadammina planata He et Li sp.nov.根据不同的环境中沉积物内有孔虫群属种组合不同,大体可归纳为二种组合:一是河口、海滩、泻湖、滨海平原等滨海边缘环境组合,在南堡以东该组合称为厚壁转轮虫——显孔鼓室希望虫组合,南堡以西称为厚壁转轮虫——多变假小九字虫组合,二是分布在水深10米以内的近岸浅海环境组合,称为厚壁转轮虫——缝裂希望虫组合。在不同环境中,有孔虫壳体数量的变化是有规律的,一般在泻湖中有孔虫含量最多,滨岸沙坝处最少,沙坝脊部有时为零,向海方向至近岸浅海共含量又有逐渐增多的趋势。  相似文献   

15.
该文探讨河北阳原—蔚县盆地早更新世沉积的泥河湾组所含有孔虫化石是否与海侵有关等问题。通过对河北平原、阳原—蔚县盆地所在地的冀西北山地及北京西山在上新世一晚更新世的地质、构造、地貌等调查、研究与分析,认为阳原—蔚县盆地早更新世时并没有发生海侵,有孔虫来源与海侵无关,属于内陆湖泊非海相有孔虫。  相似文献   

16.
Four cores (ranging between ca. 9 and ca. 14 m in length) from Lago di Albano in Central Italy were studied for their ostracod content, as well as algal and bacterial pigments, CaCO3 and concentration of organic matter. Cores PALB 94 1E and PALB 94 1C from Site 1, located at the bottom of a steep slope at 70 m water depth, where oxygen concentration is below 6 mg l-1, spans the Holocene and the late Pleistocene until 28 kyr B.P. (calibrated age). The other cores, PALB 94 6A and PALB 94 6B taken at a depth of 30 m, where oxygen is 7--11 mg l-1, represent mainly Pleistocene deposits.Ostracod valves were found in the lowermost ca. 3 m of the sequence at Site 1, dated to ca. 28--24 kyr B.P., and throughout the sequence from Site 6 which represents the interval 23--17 kyr B.P.Candona neglecta is the dominant species in most of the levels at Site 1, whereas both C. neglecta and Cyclocypris sp. dominate during different biostratigraphic zones at Site 6. The influx of springs entering the lake at Site 1 was inferred on the basis of species of the genus Potamocypris and Ilyocypris bradyi present in the record. Wide fluctuations in species abundance and assemblages in both coring sites indicate lake-water level oscillations between 28 to 17 kyr B.P. In particular, a strong rise in water level of the order of 40 m occurred between 24 and 23 kyr B.P. Fluctuations in productivity, oxygen availability and water temperature at both sites were also reconstructed on the basis of the ostracod assemblages and the algal and bacterial pigment concentrations. The environmental reconstruction reached using ostracod remains and pigments was verified with other proxy records published elsewhere such as invertebrate remains, diatoms, magnetic properties, etc. A synthesis of climatic reconstructions for Central and Southern Italy for the late Full Glacial is attempted on the basis of previous studies on hydrology, lithostratigraphy and palynology. Sharp fluctuations in lake palaeoproductivity/palaeoclimate recorded by invertebrate and pigment remains at both sites from Lago di Albano might be related to similar events reported in North Atlantic Full-Glacial records from marine and ice cores.  相似文献   

17.
The Coorong in South Australia is an internationally recognised ecologically significant coastal lagoon that extends 140 km south-east from the mouth of the River Murray. The Coorong has increasingly been impacted by a variety of human activities. Declining migratory bird abundance has been linked to the loss of Ruppia tuberosa, an aquatic plant that is the main feedstock for a wide variety of water birds. Analysis of Ruppia remains from a radiometrically dated core in the southern lagoon of The Coorong shows that the salt-tolerant annual Ruppia tuberosa has only been present at this site in recent times. By contrast, the perennial Ruppia megacarpa, which has limited tolerance to elevated salinity, appears to have been present at the site for several millennia, although it had never been observed in ecological surveys of this part of The Coorong. Diatom analysis from the same core reveals a shift from estuarine/marine assemblages to an assemblage reflective of elevated salinity levels. Charophyte, ostracod and foraminifera remains also indicate that the change in the aquatic plant community is associated with increased salinity at the study site since European settlement. Elevated salinity is the result of catchment modifications which have reduced freshwater inflows at the northern and southern extremities of The Coorong, and marine input via the Murray Mouth. This study demonstrates the utility of multiproxy palaeoecological data in addressing complex management questions. In the absence of such information, managers must ultimately rely on data sourced only from the historical record which, more often than not, is already skewed by the impact of European settlement.  相似文献   

18.
Based on the samples collected from the west wall of the ABYT2004 at Yuhuicun Site in Bengbu,Anhui Province,the multi-environmental substitute indexes such as the grain-size,Rb/Sr,zircon crystal morphology and magnetic susceptibility were analyzed.The age of archaeological strata was determined by AMS14C dating.According to the results,combined with the information of the ancient human activities and the cultural heritage data obtained from the Longshan cultural archaeological strata,it can be concluded that(1) Before 4500 aBP,the climate was humid and water level was high in the Huaihe River and its tributaries,the drainage basin and its surrounding areas were even flooded,so the site area was submerged and there were no human activities around the site.(2) About 4500 aBP,the climate began to become drier and water level of the Huaihe River and its tributaries began to decline,thus floodplain gradually appeared,Yuhuicun Site and Longshan Culture began to appear.(3) Around 4100 aBP,the climate was humid and rainfall was abundant,which resulted in frequent flood disasters in the whole Huaihe River Basin.(4) After 4100 aBP,the climate gradually transited to be cold and dry,agricultural production was constrained to reduce the food source,Yuhuicun Site was almost abandoned.(5) The environmental information in sedimentary strata and historical records based on ancient books agree with each other.In addition,Yuhuicun Site was related to Dayu Zhishui(Yu the Great in taming the floods) in ancient books.  相似文献   

19.
Based on the samples collected from the west wall of the ABYT2004 at Yuhuicun Site in Bengbu, Anhui Province, the multi-environmental substitute indexes such as the grain-size, Rb/Sr, zircon crystal morphology and magnetic susceptibility were analyzed. The age of archaeological strata was determined by AMS14C dating. According to the results, combined with the information of the ancient human activities and the cultural heritage data obtained from the Longshan cultural archaeological strata, it can be concluded that (1) Before 4500 aBP, the climate was humid and water level was high in the Huaihe River and its tributaries, the drainage basin and its surrounding areas were even flooded, so the site area was submerged and there were no human activities around the site. (2) About 4500 aBP, the climate began to become drier and water level of the Huaihe River and its tributaries began to decline, thus floodplain gradually appeared, Yuhuicun Site and Longshan Culture began to appear. (3) Around 4100 aBP, the climate was humid and rainfall was abundant, which resulted in frequent flood disasters in the whole Huaihe River Basin. (4) After 4100 aBP, the climate gradually transited to be cold and dry, agricultural production was constrained to reduce the food source, Yuhuicun Site was almost abandoned. (5) The environmental information in sedimentary strata and historical records based on ancient books agree with each other. In addition, Yuhuicun Site was related to Dayu Zhishui (Yu the Great in taming the floods) in ancient books.  相似文献   

20.
沈炎彬 《极地研究》1989,1(3):27-33
南极乔治王岛菲尔德斯半岛半三角附近的火山沉积岩,首次发现孢粉、叶化石,显示出晚白垩世的组合面貌。它们表明菲尔德斯半岛存在两个时代不同的植物层,即晚白垩世半三角植物层及始新世化石山植物层;菲尔德斯半岛火山活动始自中生代后期,而不是以前认为的侏罗纪,也非第三纪早期。这也是南设得兰群岛首次发现的晚白垩世陆相古生物证据。  相似文献   

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