上新世热带海道变化影响东亚气候的模拟研究     

谭宁  张仲石  郭正堂  王会军 《地学前缘》2022,29(5):310-321

上新世早—中期是巴拿马海道关闭及印度尼西亚海道收缩的关键时期。目前,针对这两个海道关闭的气候效应已有不少研究,但多数研究关注巴拿马海道、洋流变化及其与北半球高纬冰盖发育的联系,缺乏两大热带海道关闭/收缩对东亚气候影响及机理的研究。我们基于挪威地球系统模型(NorESM-L)探讨了印尼海道收缩及巴拿马海道的浅关闭对东亚气候的影响。结果表明,热带海道的关闭/收缩加强了北太平洋的经向梯度,进一步导致夏季近地表气温在东亚北部降低,东亚南部升高;降水在长江流域至中国东海一线显著增加,但在东亚南部至西南部显著减少。冬季,近地表气温在东亚大陆地区升高,降水减少。上述变化主要由印尼海道的收缩导致,除冬季温度外,巴拿马海道浅关闭对东亚气候的影响较弱。此外,结合定性的记录-模拟对比,我们进一步揭示出热带海道的关闭/收缩可在一定程度上影响东亚气候在中上新世的转型,但不是主要驱动力。  相似文献   

Paleoceanographic evolution recorded in the northern South China Sea since 4 Ma   总被引：2，自引：1，他引：1  

HUANG Baoqi    JIAN Zhimin & WANG Pinxian . School of Earth  Space Sciences  Peking University  Beijing  China  . Laboratory of Marine Geology  Tongji University  Shanghai  China 《中国科学D辑(英文版)》2005,48(12):2166-2173

The late Pliocene-Pleistocene is of great interest for understanding the Earth’s climate system, because not only the late Pliocene is the latest period with tem-perature significantly higher than the Holocene, but also during the Pliocene/Pleistocene transition the Earth’s environment changed from a warm and uni-form climate state into an extreme one with typical glacial-interglacial cycles. During this period the Earth’s climate experienced through the grandly phased rising of the Qing…  相似文献   

Late Pliocene Mega Debris Flow Deposit and Related Fluid Escapes Identified on the Antarctic Peninsula Continental Margin by Seismic Reflection Data Analysis     

P. Diviacco  M. Rebesco  A. Camerlenghi 《Marine Geophysical Researches》2006,27(2):109-128

We have obtained improved images of a debris flow deposit through the reprocessing of multichannel seismic reflection data between Drifts 6 and 7 of the continental rise of the Pacific margin of the Antarctic Peninsula. The reprocessing, primarily aimed at the reduction of noise, relative to amplitude preservation, deconvolution, also included accurate velocity analyses. The deposit is dated as upper Pliocene (nearly 3.0 Ma) via correlation to Sites 1095 and 1096 of the Ocean Drilling Program (ODP) Leg 178. The estimated volume is about 1800 km³ and the inferred provenance from the continental slope implies a run out distance exceeding 250 km. The dramatic mass-wasting event that produced this deposit, unique in the sedimentary history of this margin, is related to widespread late Pliocene margin erosion. This was associated with a catastrophic continental margin collapse, following the Antarctic ice sheet expansion in response to global cooling. The seismic data analysis also allowed us to identify diffractions and amplitude anomalies interpreted as expressions of sedimentary mounds at the seafloor overlying narrow high-velocity zones that we interpret as conduits of fluid expulsion hosting either methane hydrates or authigenic carbonates. Fluid expulsion was triggered by loading of underlying sediments by the debris flow deposits and may have continued until today by input of fluids from sediment compaction following the deep diagenesis of biogenic silica.  相似文献   

青海柴达木盆地西部上新世以来的地质环境与成盐期   总被引：5，自引：0，他引：5  

沈振区  童国榜 《海洋地质与第四纪地质》1990,10(4):89-99

对柴达木盆地西部大浪滩及察汗斯拉图地区的上新世晚期以来的沉积物及其孢粉化石的研究,结合古地磁、同位素年代测定,建立了九个孢粉带、九个植被演变期、三十次气候波动及三个成盐阶段。分析了本区主要成盐时期的古气候特征。 第四纪下限位于Ⅲ/Ⅱ孢粉带之间,对应于古地磁的M/G界面。中更新世底界位于Ⅵ/Ⅴ孢粉带之间,对应于古地磁的B/M界面。晚更新世底界位于Ⅷ/Ⅶ孢粉带之间,铀系测年为距今15—17万年。  相似文献   

中国第四纪地层   总被引：32，自引：0，他引：32  

刘嘉麒  刘强 《第四纪研究》2000,20(2):129-141

本文综述了中国第四纪沉积类型及第四系的划分,并与国际第四系划分进行了对比。指出中国第四纪沉积物分布广泛,种类繁多,以陆相沉积为主。按其成因主要有风成黄土堆积、河一湖相沉积、冲一洪积堆积、冰川沉积、洞穴堆积、风化壳残积（红土）、火山堆积和海相沉积等。各种沉积物都有很好的剖面,尤其是黄土和河一湖相沉积更为连续完整。按中国第四纪地层发育的实际情况,第四系的底界应置于松山一高斯极性转换界线（Ｍ／Ｇ,２．６ＭａＢ,Ｐ,）;第四系内部划分为更新统（Ｑ_ｐ）和１４新统（Ｑ_ｈ）,界线在１１０００ａＢ,Ｐ,。更新统进一步划分为下、中和上３个阶(Ｑ_ｐ１, Ｑ_ｐ２, Ｑ_ｐ３), Ｑ_ｐ２／Ｑ_ｐ１的界线为布容一松山极性转换界线（Ｂ／Ｍ; ０．７８ＭａＢ,Ｐ,）;Ｑ₍ｐ３_／Ｑ_ｐ２的界线为本次间冰期的起始时间（０．１２８ＭａＢ,Ｐ,）。  相似文献   

CHARACTERISTICS OF ALKALINE VOLCANIC ROCKS OF PLIOCENE IN THE WESTERN PART OF HONGHE FAULT ZONE     

Wang Guozhi  Huang Yongjian  Ma Renze  Wang Chengshan WT  ”BX 《地学前缘》2000,(Z1)

CHARACTERISTICS OF ALKALINE VOLCANIC ROCKS OF PLIOCENE IN THE WESTERN PART OF HONGHE FAULT ZONE  相似文献   

南海ODP1143站上新世至更新世天文年代标尺的建立   总被引：8，自引：3，他引：5  

田军  汪品先  成鑫荣  李前裕 《地球科学》2005,30(1):31-39

基于底栖有孔虫δ18O的精确的年代标尺是古海洋学研究的基础, 特别是长度超过5 Ma, 分辨率小于5 ka的连续δ18O记录在全球大洋深海记录中更是凤毛麟角.在大西洋和东太平洋已经建立起了类似的代表性剖面, 如大西洋ODP659站和东太平洋ODP846站, 但在对全球气候有着重要影响的“西太平洋暖池区”还没有建立起这样的剖面.以南海大洋钻探184航次1143站底栖有孔虫的δ18O为材料, 建立了西太平洋地区跨越5 Ma、分辨率达2~ 3 ka的天文年代标尺.天文调谐的基本原理参照Imbrie et al.(1984), 并将斜率周期上8 ka的相位差和岁差周期上5 ka的相位差从晚更新世扩展到5 Ma; 调谐目标选用Laskar(1990)的斜率和岁差; 调谐方法采用了有别于ODP659站和ODP846站的自动轨道调谐方法(Yu and Ding, 1998).调谐结果显示, 1143站190.77 m、191个冰期、间冰期的深海沉积记录了5.02 Ma的南海古海洋学历史; 1143站布容/松山磁性反转事件的年龄为0.78 Ma, 与前人研究结果一致; 15个识别出的浮游有孔虫生物事件年龄部分与已经发表过的年龄相吻合, 部分为该生物事件在南沙海区的新年龄.由年代标尺推导出的南海沉积特征显示, 2.9 Ma是沉积速率的一个转折点, 在此之前, 平均线性沉积速率只有39.5 m/Ma, 冰期、间冰期平均波动幅度为50 m/Ma; 2.9 Ma以后, 平均线性沉积速率猛然上升到65.4 m/Ma, 冰期、间冰期平均波动幅度为200 m/Ma.此外, 南海的沉积速率还显示出冰期或间冰期中的亚冰阶沉积速率高, 而相邻的间冰期或亚间冰阶的沉积速率低, 这种特点在更新世尤为典型.这可能与全球冰量变化带来的冰期、间冰期差异性风化剥蚀和搬运有关.   相似文献   

南沙海区晚上新世海水上层结构变化     

李建如  汪品先 《海洋地质与第四纪地质》2004,24(4):67-71

对南沙海区水深2772m的ODP1143站100～150m井段共101块沉积样品进行了浮游有孔虫分析,结果表明,从3．27Ma到2．55Ma该区表层海水温度逐步降低,温跃层逐步加深,推测是晚上新世北半球冰盖形成过程中,东亚季风相应加强的结果。与此同时,南沙与南海北部的温跃层深度差值不断加大,可能是西太平洋暖池最终形成或加强的表现。3．2Ma前后,表层海水温度和海水温跃层深度都发生了急剧变化,反映出北半球冰盖和西太平洋暖池的发育可能存在一定的相关性。  相似文献   

Neogene marine sediments and biota encapsulated between lava flows on Santa Maria Island (Azores,north-east Atlantic): An interplay between sedimentary,erosional and volcanic processes     

Alfred Uchman  Markes E. Johnson  Ricardo S. Ramalho  Rui Quartau  Björn Berning  Ana Hipólito  Carlos S. Melo  ANA C. Rebelo  Ricardo Cordeiro  Sérgio P. Ávila 《Sedimentology》2020,67(7):3595-3618

Sedimentary rocks are rarely preserved on reefless volcanic oceanic islands because their sediments are mostly exported from coastal areas towards the deep sea and such islands typically undergo subsidence. In contrast, the exceptional geological record of the uplifted Santa Maria Island (Azores) provides a unique opportunity to gain insight on such coastal systems. This study focuses on a locality at Ponta do Cedro (eastern Santa Maria Island), which features a series of marine fossiliferous sediments wedged between steep lava deltas. As demonstrated by local structure, these sediments correspond to clinoforms deposited on the steep submarine slope of an active volcanic island, implying transport from shallow waters to greater depths and subsequent colonization by benthic communities. Rapid volcanic progradation eventually sealed the deposits, allowing for their preservation and providing a rare snapshot of the ecology during those intervals, in addition to insights on sedimentary dynamics along submarine island slopes. This study reveals spatial relationships between wedges of sedimentary bodies encapsulated by lavas in the Ponta do Cedro section, and interprets depositional processes preserved in those strata based on sedimentological and palaeontological data. The dynamics of the environment are mostly related to relative sea-level changes, intense volcanic activity and regional uplift during the Neogene.  相似文献   

滇西道街盆地上新世怒江埋藏砾石层、堰塞湖沉积 的发现及其磁性地层学     

赵希涛  仝亚博  吴中海  叶培盛  胡道功 《地质通报》2012,31(203):227-234

在对怒江道街—惠通桥段的考察研究中,不仅重新厘定了河谷中拔河150m以下的多级低阶地,而且在拔河180～380m的高度上发现了多级由磨圆良好、成分复杂的厚层冲积砾石层所组成的高阶地,厚近100m的堰塞湖成因的砂层及其下伏厚约100m的砾石层。冲积层的同位素年龄测定结果表明,6级低阶地形成于中更新世以来。望江楼剖面的磁性地层研究结果显示,组成相当于第九级阶地上部的湖相砂层,上部以正向极性为主,含2次短期的负极性,下部则为负极性。与标准磁性地层柱对比表明,该湖相地层形成于4.2～2.6MaBP的中—晚上新世,湖相地层之下的埋藏阶地与高阶地则应形成于上新世早期至中新世晚期。据此在进一步的区域地层对比后认为：怒江至少在中新世的中晚期已开始形成并下切,至上新世早期已下切至现今河床附近。上述研究结果为更科学地认识青藏高原东缘的强烈隆升过程提供了非常有价值的新线索。  相似文献