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1. chinaXiv:201811.00064 [pdf]

地表风化作用对楼兰地区雅丹地貌发育的影响

林永崇; 穆桂金
分类: 地球科学 >> 地质学

风蚀是雅丹地貌发育的主要控制因素,但是在特定环境中,其他环境因素也可能起重要作用。本研究通过对楼兰地区雅丹地貌野外调查、测试及室内实验分析,探讨风化作用对雅丹发育的影响。结果发现:新疆罗布泊地区广泛发育雅丹地貌,其中楼兰地区雅丹相对较为矮小,主要发育于全新世沉积岩上,地表没有植被或松散沉积物等覆盖,地层裸露。楼兰雅丹体为黏土质粉砂岩,干燥条件下较为坚硬(>20 Kg•cm-2),抗风蚀能力较强,但是雅丹体表层岩性发生明显软化(<10 Kg•cm-2)。这主要是由于罗布泊地区虽然降雨量十分稀少,但这些少量且集中的降水、地表昼夜温差导致大气水分凝结以及强烈太阳辐射等相互作用造成的。从这些广泛存在的松软层表明,雅丹体风化作用速度快于风蚀作用,而首先进行的表层风化作用,对雅丹风蚀作用起很大的促进作用,明显加速了楼兰地区雅丹地貌的发育。因此,受少量降水、昼夜温差和强烈的太阳辐射等影响的风化作用对楼兰地区雅丹地貌发育具有重要的影响。

提交时间: 2018-11-13 来自合作期刊:《干旱区地理》 点击量744下载量129 评论 0

2. chinaXiv:201810.00139 [pdf]

1996—2016年西藏定结地区风沙地貌格局与变化

马建军; 潘美慧; 伍永秋
分类: 地球科学 >> 地质学

本文采用1996—2016年定结地区Landsat4-5 TM、MSS、Landsat7 ETM、Landsat8 OLI共6期遥感影像,结合野外实地考察,对西藏定结地区风沙地貌特征及近20年来风沙地貌格局动态变化进行了定量研究。结果表明:(1)定结地区风沙地貌类型主要有爬坡沙丘、谷坡灌丛沙堆、新月形沙丘、平沙地及谷底灌丛沙堆,主要沿朋曲河、协林藏布、叶如藏布、吉隆藏布及曲强藏布等河谷呈条带状分布并集中在宽谷段,同时在登么错、强左错、共左错及错母折林等湖泊周围呈小面积零星分布。(2)1996—2016年定结地区风沙地貌格局变化分为两个阶段:1996—2004年呈扩张趋势,年转换率为0.87,增加量为151.2 km2;2004—2016年呈逆转趋势,年转换率为-0.59,减少量为276.6 km2。整体而言,1996—2016年总面积转化率为-0.27,风沙地貌面积呈先扩张后缩减趋势,转移矩阵分析流动沙地向固定、半固定沙地转移较多,这种变化特征与转移方向印证了青藏高原气候暖湿性愈发显著的趋势。

提交时间: 2018-10-23 来自合作期刊:《干旱区地理》 点击量503下载量142 评论 0

3. chinaXiv:201810.00140 [pdf]

则岔石林地质公园喀斯特地貌类型及形成机制

徐家红; 鄢志武; 柳晓丹
分类: 地球科学 >> 地质学

则岔石林地质公园位于甘肃省碌曲县,该处地貌完整地保存了高寒喀斯特的特征,具有典型性与稀有性。为了揭示其自然科学价值,促进自然资源开发与景观保护,基于前人工作基础,通过野外地质调查,以碌曲县区域地学为背景,介绍了则岔石林地质公园的喀斯特地貌类型,即以高原石林为主,一线天为亮点,小型溶洞为辅。继而从地质构造、岩性、水文气候、生物因素四方面分析了园内喀斯特地貌的形成机制。对完善我国高海拔地区岩溶系列地质遗迹的科学研究具有一定意义。同时,高寒喀斯特的生态化对南方喀斯特沙漠化的治理具有良好的示范作用。

提交时间: 2018-10-23 来自合作期刊:《干旱区地理》 点击量507下载量125 评论 0

4. chinaXiv:201810.00141 [pdf]

新疆孔雀河北岸72~51ka BP湖相沉积物的孢粉植物群初步研究

白友良; 赵振华; 孙琦; 李博
分类: 地球科学 >> 地质学

对新疆孔雀河北缘的LX02剖面湖相沉积物开展了OSL测年和孢粉记录研究。结果显示,该剖面湖相沉积自72.4ka B.P.延续到51.0 ka B.P.。这一期间,研究区为针叶、阔叶混交林植被,林下生长灌木和草本,低洼潮湿的地方生长蕨类孢子和藻类。植被的主要类型有松(Pinus)、栎(Quercus)、栗(Castanea)、榛(Corylus)、莎草(Cyperaceae)、蒿(Artemisia)、藜(Chenopodiaceae)、水龙骨科(Polypodiaceae)等,同时还含有少量的山核桃(Carya)和枫杨(Pterocarya)等亚热带的孑遗植物花粉。具体来说, 组合带Ⅰ(72.4~66.8ka B.P.)、Ⅲ(56.1~51.0ka B.P.)对应的沉积期间,研究区阔叶树花粉含量低而灌木和草本花粉含量高;组合带Ⅱ(66.8~56.1ka B.P.)对应的沉积期阔叶树花粉含量都较高,而灌木和草本花粉相对较低,揭示72.4~51.0ka B.P.研究区气候总体上呈现冷干-暖湿的气候波动特征。这与粘土矿物和地球化学特征所反映的古气候特征及其变化一致,亦与柴达木盆地东部介形类丰度特征研究、柴达木盆地东部古湖泊高湖面光释光年代学研究、北京平原区有机碳同位素研究等结果吻合较好。不过,这一气候变化规律的内部驱动机制还有待进一步深入研究。

提交时间: 2018-10-23 来自合作期刊:《干旱区地理》 点击量779下载量141 评论 0

5. chinaXiv:201810.00142 [pdf]

中条山北麓河流地貌参数及其新构造意义

徐伟; 袁兆德
分类: 地球科学 >> 地质学

基于数字高程模型(DEM)及地理信息系统(GIS)技术,系统提取和分析了中条山北麓河流坡降指标、河道陡峭指数及面积高程积分等河流地貌参数。研究表明:河流坡降指标、河道陡峭指数及面积高程积分在永济至解州一带表现出较高的值;综合分析岩性、降水及构造等因素可知,新构造运动是控制中条山北麓河流地貌发育的主要因素,自北向南总体表现出增强的趋势,在永济南活动最强。前人研究表明,中条山北麓断裂晚第四纪以来构造活跃,全新世以来仍有多次活动,但不同部位活动强度各异,解州段晚更新世晚期以来滑动速率相比韩阳段及夏县段高,极高值在出现在永济南一带。可见,基于河流地貌参数获得的中条山北麓新构造运动强弱与断裂晚第四纪以来的活动强弱一致。

提交时间: 2018-10-23 来自合作期刊:《干旱区地理》 点击量746下载量136 评论 0

6. chinaXiv:201804.01249 [pdf]

Negligible effect of tooth reduction on body mass in Mesozoic birds

ZHOU Ya-Chun; ZHANG Fu-Cheng; Corwin SULLIVAN
分类: 地球科学 >> 地质学

Tooth reduction and loss was an important evolutionary process in Mesozoic birds. Analysis of evolutionary trends in the total mass of the dentition, a function of tooth size and tooth number, has the potential to shed light on the evolutionary pattern of tooth reduction and loss, and on the causes of this pattern. Because modern birds lack teeth, however, they cannot provide the basis for a model that would allow estimation of tooth masses in their Mesozoic counterparts. We selected the teeth of crocodilians as analogues of those in Mesozoic birds because the former are the closest living relatives of the latter, and the two groups are similar in tooth morphology, tooth implantation, and tooth replacement pattern. To estimate tooth masses in Mesozoic birds, we formulated four regression equations relating tooth mass to various linear dimensions, which were measured in 31 intact isolated teeth from eight individual crocodiles (Crocodylus siamensis). The results for Mesozoic birds show that dental mass as a proportion of body mass was negligible, at least from the perspective of flight performance, suggesting that selection pressure favoring body mass reduction was probably not the primary driver of tooth reduction or loss. Variations in dental mass among Mesozoic birds may reflect the different foods they ate, and the different types of feeding behavior they displayed.

提交时间: 2018-04-04 来自合作期刊:《古脊椎动物学报》 点击量1335下载量371 评论 0

7. chinaXiv:201804.01250 [pdf]

A new species of Kubanochoerus (Suidae, Artiodactyla) from the Linxia Basin, Gansu Province, China

HOU Su-Kuan; DENG Tao
分类: 地球科学 >> 地质学

A new specimen of kubanochoeres has been discovered from the Maida locality, Linxia Basin, Gansu Province, China, and a new species, Kubanochoerus parvus sp. nov., has been created based on the unique partially broken cranium. The new species has a relatively small body size similar to K. massai and K. minheensis. The new species, which possesses relatively wide cheek teeth that resemble those of K. massai and many derived characters that are similar to K. gigas, may represent a separate lineage of the Eurasian kubanochoeres. The horizon of the Maida locality is speculated to be the upper Hujialiang Formation or lower Liushu Formation, and the new species is possibly the youngest known kubanochoere. Based on the comparison of the known kubanochoere, Libycochoerus is suggested to be a synonym of Kubanochoerus, while K. robustus and K. lantienensis are synonyms of K. gigas. There is not sufficient evidence to support the subdivision of K. gigas at the subspecies level. Kubanochoerus gigas is speculated to have derived from more primitive forms that existed earlier than K. massai, and the new species may be derived from K. massai or other earlier forms. Kubanochoerus minheensis, which bears a relatively small body size and rudimentary sub-lophodont dentition, is suggested to be another separate lineage of the Eurasian kubanochoeres.

提交时间: 2018-04-04 来自合作期刊:《古脊椎动物学报》 点击量1439下载量471 评论 0

8. chinaXiv:201804.01251 [pdf]

Fossil gibbons (Mammalia, Hylobatidae) from the Pleistocene of Chongzuo, Guangxi Zhuang Autonomous Region, China

ZHANG Ying-Qi; JIN Chang-Zhu; WANG Yuan; Alejandra ORTIZ; HE Kai; Terry HARRISON
分类: 地球科学 >> 地质学

Recent fieldwork at Pleistocene cave sites in the Chongzuo area in Guangxi Zhuang Autonomous Region has yielded 33 isolated teeth of fossil hylobatids. Comparisons indicate that the teeth can all be referred to a single species of Nomascus, but the material is insufficient to assign it to a particular species. The molars are slightly larger on average than those of extant species of Nomascus, but unlike contemporary great apes from the Pleistocene of southern China, the hylobatids do not seem to have undergone a change in dental size through time. Nomascus is not present in the Chongzuo area today, but historical records indicate that the genus may have been widely distributed across southern China in the recent past.

提交时间: 2018-04-04 来自合作期刊:《古脊椎动物学报》 点击量1694下载量408 评论 0

9. chinaXiv:201803.00011 [pdf]

New material of the Late Miocene Moschus (Artiodactyla, Mammalia) from Huade, Nei Mongol, North China

DONG Wei; LIU Wen-Hui; ZHANG Li-Min; BAI Wei-Peng; CAI Bao-Quan
分类: 地球科学 >> 地质学

Moschus grandaevus was firstly uncovered from the Late Miocene deposits at Ertemte, Olan Chorea, Harr Obo and Hua Ba in or around Huade County in the middle part of Nei Mongol and was described by Schlosser in 1924. The excavations by Sino-Soviet Joint Paleontological Team in 1959 and recent excavations since 2013 at Tuchengzi (Tuchetse), another locality at Huade, accumulated many specimens of the musk deer. The morphology and metric studies show that the musk deer specimens from Tuchengzi are the same as those described by Schlosser and can be included into the same species. M. grandaevus ranges from Siberia of Russia to North China, and likely to southern China, in the Late Miocene and Pliocene. The appearance of such folivorous musk deer in the Late Miocene deposits at Tuchengzi indicates that there were forests there during that period. The cladistic analyses show that the fossil species of Moschus are closely related to each other and can be grouped together as Moschini or Moschinae. Micromeryx is closer to Moschus and Cervidae, but the relationship between Micromeryx and Moschus is more complicated than previously considered; nonetheless Hispanomeryx is closer to Bovidae. Schlosser (1924)记述了最初发现于内蒙古化德境内或附近的二登图、敖兰卓蕾、哈尔敖包及华坝的古麝(Moschus grandaevus)。1959年中苏古生物考察队在化德的另一个地点土城子采集到不少古麝化石。2013年以来作者在土城子进行的野外发掘积累了更多的古麝化石标本。土城子标本在形态和测量数据方面和二登图等地点的古麝非常接近,可以归入同一种。根据现有资料归纳,古麝的地理分布范围自俄罗斯的西伯利亚到华北,很可能延伸到华南;其地质时代分布范围为晚中新世–上新世。食叶型古麝在土城子晚中新世地层中的出现说明当时土城子一带有森林环境。支序分析显示麝属(Moschus)化石种相互之间的系统关系非常近,可以归并为麝族(Moschini)或麝亚科(Moschinae); Micromeryx更接近麝属和鹿科,它与麝属之间的关系比以前认为的复杂,而Hispanomeryx更接近牛科。

提交时间: 2018-03-02 来自合作期刊:《古脊椎动物学报》 点击量3242下载量617 评论 0

10. chinaXiv:201802.00746 [pdf]

Reappraisal of Endotherium niinomii Shikama, 1947, a eutherian mammal from the Lower Cretaceous Fuxin Formation, Fuxin-Jinzhou Basin, Liaoning, China

WANG Yuan-Qing; KUSUHASHI Nao; JIN Xun; LI Chuan-Kui; SETOGUCHI Takeshi; GAO Chun-Ling; LIU Jin-Yuan
分类: 地球科学 >> 地质学

Reinvestigation of the Early Cretaceous eutherian mammal Endotherium niinomii Shikama, 1947, based on the impressions of the type specimen, casts made from the impressions, and the original description, indicates that E. niinomii is characterized by the following characters: decrease in size from the m1 to the m3; a moderate height difference between the trigonid and talonid of lower molars; blunt lower molar cusps; the protoconid being the largest among the trigonid cusps; the paraconid being as tall as the metaconid; the p3 not being obviously reduced; and possible possession of five lower premolars. These characteristics clearly distinguish E. niinomii from other known Cretaceous eutherians, and support its taxonomic identity as a valid taxon.

提交时间: 2018-02-26 来自合作期刊:《古脊椎动物学报》 点击量2225下载量547 评论 0

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