Paleomagnetic Excursions Recorded in the Yanchi Playa in Middle Hexi Corridor, NW China Since the Last Interglacial     

YANGTaibao YUYongtao LIJijun ANCongrong LIUJinfeng ZHANGJunyan 《山地科学学报》2004,1(2):128-142

Paleomagnetic determinations on lithologieal profiles of two paralleled long drillin gcores covering the past 130 kyr B.P., GT40 and GT60,from the Yanchi Playa in the arid Northwestern China indicate that a series of pronounced paleomagnetic excursions have been documented. By correlating our results with published regional and worldwide reports 4 excursion events out of 10 apparent reversal signals (labeled from GT-1 to GT-10) were identified as excursion events coeval with the Mono Lake Event (28.4 kyr-25.8 kyr), Laschamp Event (43.3 kyr-40.5kyr), Gaotai Event (82.8 kyr-72.4 kyr) and the Blake Event (127.4 kyr-113.3 kyr), respectively. GT-9 correlates with the above-mentioned Gaotai Event,GT-7 and GT-6 correspond to two stages of the Laschamp Event and GT-5 to the Mono Lake Event. It is noteworthy that the so-called Gaotai Event has not been reported as a pronounced paleomagnetic excursion in the Northwestern China. Every magnetic excursion event corresponds to paleointensity minima, anteceding those established abrupt paleoclimatic change events, such as the Younger Drays and the Heinrich Events (H1-H6). Here, we tentatively propose that these geomagnetic excursions/reversals can be viewed as precursors to climate abruptness. During the transitional stages when the earth‘s magnetic field shifted between a temporal normal and a negative period, the earth‘s magnetic paleointensity fell correspondingly to a pair of minima. Although more precise chronology and more convincing rock magnetic parameter determinations are essentially required for further interpretation of their intricate coupling mechanism, these results may have revealed, to some extent, that the earth‘s incessantly changing magnetic field exerts an strong influence on the onset of saw-tooth shaped abrupt climate oscillations through certain feedback chains in arid Central Asia or even North Hemispheric high latitude regions.  相似文献   

中国古日食记录和地球自转长期变化     

张培瑜 《紫金山天文台台刊》1994,13(1):23-31

古代日月食观测记录是研究过去几千年地球自转长期变化的最有用的材料, 本文对文献记载的中国古代(明末以前)的日食观测作了分析讨论。指出,西汉以后资料是系统完整的。多为当时首都的观测记录。可惜的是,古人不重视记录天象发生的准确时刻。 作者从这些材料中筛选出13次观测地点明确的日全食观测,探讨分析了地球自转长期变化的趋势。  相似文献   

扬子地台北缘晚震旦世微古植物特征及意义     

陈会鑫  丁莲芳  秦洪宾 《地球科学与环境学报》1994,(3)

本文着重研究了扬子地台北缘上震旦统陡山沱组、灯影组及下寒武统下部岩家河段的微古植物组合特征。初步建立了Ⅰ、Ⅱ两个微古植物组合，分别与陡山沱村阶和灯影峡阶相对应，分析了微古植物组合在地层划分与对比及在震旦系－寒武系界线的划分上所起的作用。  相似文献   

嵩县黄庄—汝阳三屯熊耳群火山岩古火山机构地质特征     

王令全  左景勋  刘良才 《河南国土资源》1997,(1)

嵩县黄庄—汝阳三屯一带熊耳群火山岩分布区属构造变动强烈的中深剥蚀区。依据岩石岩相标志、断裂构造形迹、火山岩区的产状以及地貌标志等，区内首次识别出了活动于鸡蛋坪期、马家河期的五个古火山口和一个古裂隙喷发带，并对许山期的火山活动特征进行了分析。熊耳群火山活动的早期为北西向的裂隙喷溢；中期以中心式喷发为主，并伴有裂隙式喷发；晚期演化为中心式喷发。区域火山活动表现为自北东向南西由早到晚  相似文献   

湘中晚泥盆世早期的两个古群落分析     

赵兵 《成都地质学院学报》1990,17(4):23-32

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Characteristics and evolution of lacustrine turbidite of Chang-7 Member of Yanchang Formation in northern Shaanxi     

PANG Jungang  LI Wenhou  XIAO Li. School of Petroleum Resources  Xi'an Shiyou University  Xi'an  China. Geological Department  Northwest University  Xi'an  China. State Key Laboratory of Continental Dynamics  China. Geological Research Institute of Shengli Oilfield Co. Ltd.  SINOPEC  Dongying  Sh  ong  China 《东北亚地学研究》2009,(4):183-188

Lacustrine turbidite of Chang-7 Member in the studied area consists of sihstone and fine sandstone with respect to grain size, which is feldspathic lithie sandstone, syrosem arkose and arkose with respect to mineral constitution affected by provenance. There are such apparent signatures as lithology, sedimentary structure, sedimentary sequence and well logs, to recognize turbidite. During the paleogeographic evolution of Chang-7 Member, lake basin and deep lake are both at their maximum extent during Chang-73 stage, resulting in the deposition of Zhangjiatan shale with widespread extent and of turbidite with fragmental-like. Deep lake line is gradually moving toward lake center and turbidite sand bodies are gradually turning better with better lateral continuity, connectivity and more thickness, from stages of Chang-73, Chang-72 and Chang-7t, which can be favorable reservoir in deep-water.  相似文献   

三水盆地发现5000万年前化石     

《国土资源》2009,(4)

日前，中科院古脊椎动物与古人类研究所研究员经实地考察证实，广东三水盆地发掘出了华南首个5000万年前鸟化石，同期发现的还有2只青蛙化石、20余块5000万年前的骨舌鱼类化石以及完整的茂名无盾龟化石。“三水盆地发现的鸟化石，既是华南地区始新世又是中新世发现的第一块。”中科院古脊椎动物与古人类研究所研究员张江永评价认为，“2只青蛙化石是华南地区的首次发现，  相似文献   

最原始的”羽毛”     

《国土资源》2009,(1)

中国古生物学家徐星、郑晓延、尤海鲁在山东天宇自然博物馆收藏的一件北票龙（兽脚类恐龙的一种，图为其复原图）标本上发现了一种形态非常奇特的原始羽毛——一种类似毛发的单根细丝状结构。随后又在中科院古脊椎动物与古人类研究所收藏的另外一件北票龙标本的尾部发现了类似的结构。  相似文献   

宁绍平原史前遗址、埋藏泥炭与中全新世海面变化   总被引：4，自引：0，他引：4       下载免费PDF全文

史威  马春梅  焦锋  朱诚  王富葆 《海洋学报》2008,30(4):169-175

浙江萧山跨湖桥遗址的年代学证据表明[1-6],新石器时期宁绍平原西部距今8000a前后已有人类活动,较华东其他沿海平原区新石器时期人类活动的上限提早了近1000a。由于该区恰处于全新世最大海侵的敏感部位,遗址地层有可能反映最大海侵前后的海面变化状况;另一方面,继跨湖桥和下孙遗址遭受海侵[4-7]之后,时代较晚的河姆渡遗址出现在宁绍平原中部,这可能暗示此时本区已进入了一次海退阶段或相对低海面期。  相似文献   

《海洋地质与第四纪地质》第28卷(2008)总目录     

《海洋地质与第四纪地质》2008,28(6)

  相似文献