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前言珠穆朗玛峰地区系指西藏雅鲁藏布江以南,亚东以西,吉隆以东的我国境内广大地区。在解放以后,曾有多次科学考察,尤其在1966年至1968年,由中国科学院组织西藏科学考察队,对这一地区进行了大规模的多学科考察。 相似文献
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滑塌堆积(Olistostrome)一词是1955年弗洛里斯(Flores)在讨论有关西西里地区的地质现象时提出的,用以表示存在于沉积序列中的异质的、结构多少有些混乱的堆积体。对类似堆积物的研究可追溯到上一世纪的末期,但在名称的用法和成因的解释上一直存在争论。 西藏南部的滑塌堆积分布相当广泛,在雅鲁藏布缝合线的南侧,东起羊卓雍错,西至萨噶县城南的扎扎拉山口一带有多处出露,构成一个断续分布的带。 本文研究了西藏南部滑塌堆积的分布和产状,着重阐述了它们在沉积学上的特点,并讨论了它们的成因和形成过程。 相似文献
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西藏日喀则—白朗一带规模宏大的蛇绿岩套,是雅鲁藏布蛇绿岩系发育最好的地段之一,1980年6—8月,中国科学院地质研究所青藏考察队对该区蛇绿岩地质做了系统地、全面地考察,较详细填制了该区的蛇绿岩地质图和构造体系图。调查结果表明,在以镁铁质为主的基性和超基性火成岩上部,普遍沉积有数百米厚的深海蛇绿质沉积岩系(照片1),经初步研究发现,在其下部夹有厚薄不同的沸石层。 相似文献
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作者对1973-1975年中国科学院青藏高原综合科学考察队和1975年中国登山队科考分队地质组,在西藏南部和珠穆朗玛峰（以下简称珠峰）地区采集的部分同位素地质年龄样品,经镜下鉴定,选择适宜者用钾氩法做了同位素地质年龄的测定,从而对本区广泛出露的岩浆岩和变质岩的时空分布特征加深了认识。在工作中钾是用火焰光度法测定的。放射成因氩的含量大部分是用体积法测定,小部分用以Ar38为稀释剂的稀释法测定。 相似文献
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对于铬矿床,特别是对“非层状”超基性岩体内的铬矿床的成因和成矿规律,是一个尚未解决的地质问题。笔者在学习前人成果的基础上,根据1975—1977年的野外观察及室内鉴定分析,结合附生及造矿铬尖晶石类型、成矿与岩相及构造的关系,对西藏某铬矿床的成因进行了分析研究。 相似文献
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《Quaternary Science Reviews》2007,26(13-14):1884-1896
Past analogs for our present interglacial have been sought for better understanding of our present and future climate. Marine Isotope Stage 11 (MIS 11) has long been considered to be a good candidate and has gained increasing attention in recent studies of marine and terrestrial records. In the Chinese loess–paleosol sequences, S4 soil, interpreted as equivalent to MIS 11, yields a very precise terrestrial paleoclimate record of environmental changes that prevailed during this period. In this study, two high-resolution terrestrial mollusc records from the Loess Plateau have been analyzed to characterize climate variability during the periods of MIS 12–10. The changes in environment and climate, indicated by the variations in abundance of land mollusc species, are thus documented. Our mollusc results show that the L5 loess, equivalent of MIS 12, developed under relatively cold and dry conditions. Climate during this period was not as severe as indicated in the marine isotopic records. An episode of warmer and more humid condition occurred at the middle stage of the MIS 12, reflecting a summer monsoon strengthened during the glacial interval. A similar scenario has been observed in the middle part of MIS 10. In addition, our mollusc records provide insight into the climate conditions over the Loess Plateau during MIS 11, a general warm–humid climate dominated during the formation of S4 soil. But at least four fluctuations occurred at Xifeng region, reflecting unstable climate conditions and regional climate differences within the Loess Plateau during this period. Our study shows that the early part of S4, spanning over 30 ka, was very warm and humid, while the late part was characterized by mild-cool conditions. Comparison of mollusc species compositions of both MIS 11 and Holocene intervals reveals different climate conditions. The early part of MIS 11 was warmer and more humid than the Holocene optimum period, while the late part of MIS 11 was similar or cooler. Our study indicates that the extent of warming during the Holocene in the Loess Plateau might be significantly less than the conditions that prevailed during the MIS 11 interglacial period. 相似文献
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海洋沉积物中的某些主微量元素与沉积物源区有着密切的联系,它们之间的比值变化受到源区化学风化强度的影响,因此这些元素的比值变化可以反映出海洋沉积物源区古气候的变化。本文研究了南海北部陆坡MD12-3432站位深海氧同位素6期和5期(MIS6/5) 沉积物的主微量元素,发现其表现出良好的气候控制变化特征,K/Ti、Mg/Ti、Al/Ti、Fe/Ti、Co/Ti、Zn/Ti和V/Ti等比值在MIS 5期时较高,而在MIS6期时较低。南海北部的碎屑物质主要来自中国华南地区,沉积物中元素比值的变化表明间冰期时(MIS5)华南地区陆壳化学风化增强,说明该时期华南陆地气候环境温暖湿润,这可能是间冰期时东亚夏季风加强的结果;而冰期时南海北部沉积物源区化学风化减弱,则与此时东亚冬季风较强,华南地区气候干燥寒冷相关。同时,与表层海水生产力相关的Ba/Ti比值在间冰期较高而冰期较低,反映出南海北部在间冰期时表层生产力较高而冰期时相对较低,这可能是由于东亚夏季风增强带来更多降雨,陆地化学风化作用加强,大量营养成分随河流进入南海,导致南海北部表层海水生产力增加。 相似文献
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喜马拉雅山脉是地球上最高、最长大和最年青的山脉之一。它以宏伟的规模和巨大的海拔高度强烈地影响着我国西藏地区以至亚洲中部自然环境的变化。自1949年中华人民共和国成立以来,在毛主席和党中央的关怀下,曾对珠穆朗玛峰及邻近地区进行过多次考察。在无产阶级文化大革命的1966-1968年,又进行了珠峰地区多学科的科学考察。 相似文献
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羌塘盆地查郎拉地区中新生代古气候演化初探 总被引：6，自引：2，他引：6
通过野外遥感调研和收集整理大量剖面及路线地质资料，讨论了羌塘盆地查郎拉地区气候常量元素、变价元素及微量元素特征；气候沉积物及其分布特征，结合已有的气候指示性古生物化石及岩相古地理资料，首次系统地演绎了本区中新生代古气候特征及其变迁演化史。划分出8个气候旋回，指出晚三叠世为热带亚热带温热半潮湿－潮湿气候，组成第I气候旋回；中株罗世呈热带亚热带半干旱→半潮湿气候的周期性变化，组成第Ⅱ、Ⅲ气候旋回；晚株罗纪经历了热带炎热半干燥→温暖半潮湿和潮湿→炎热半干燥气候的演化，组成第Ⅳ、Ⅴ气候旋回；白垩纪气候早期呈温暖半潮湿，晚期转为半干燥－干燥热带、亚热带气候，组成第既Ⅵ、Ⅶ气候旋回；第三纪为内陆亚热带的干燥、半干燥→高原温凉气候；第四纪曾出现过6次冰期和5次间冰期，新生代总体经历了剧烈而频繁的冷暖波动，气候日益干燥和寒冷。最后简单分析了气候旋回与沉积旋回、构造运动和青藏高原隆升的叠加耦合关系，以及古气候变迁的主因。 相似文献
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Karl Tilman Rost 《GeoJournal》1994,34(1):107-120
Recent investigations in and along the mountains south of the Loess Plateau (Central China) give no evidence of Pleistocene glaciations below 2800 m asl. Reliable Late-Pleistocene glacial landforms and till only occur in the Qinling Shan (3767 m). The paleosnowline in altitudes of 3250–3300 m was more than 1000 m lower than at present. A Late-Pleistocene periglacial region has been descended to about 2300 m asl, resulting an increase of the sediment yield of the rivers and intensified sediment aggradation in the valleys in and along the Qinling Shan. The Late-Pleistocene descend of the coniferous forest was comparable to the snowline depression. A spruce-fir forest dominated along the northern flank of the mountain range during the time 30-20 ka BP. Towards the end of the Pleistocene glacial periods respectively at the beginning of the following interglacial phase, dissection of alluvial deposits and terracing began in the mountain valleys and in the northern foreland. The replacement of forest vegetation by a more steppe-like vegetation as well as the loess accumulation along the northern Qinling Shan indicates increasing aridity as the climate warmed at the end of the last glacial period and during the Early Holocene. The widespread occurrence of Mid-Holocene paleosols within the loess proves a more moist and warm interval, which is followed by a drier and cooler Late Holocene period. 相似文献
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Amalava Bhattacharyya Nivedita Mehrotra Santosh K. Shah 《Journal of the Geological Society of India》2011,77(6):521-526
Palynological analysis of sub surface samples at 1.20 m deep sediment profile from Srinagar, southwest Tripura, provides information
on vegetation and climate during 7000–3000 years B.P. During this time span, the area is occupied by moist deciduous forest
under warm humid climate with intermittent changes in precipitation regime i.e., comparatively less humid around 6.8 Kyr B.P.
and 3.7–3.8 Kyr B.P. 相似文献
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第四纪冰期与间冰期旋回的形成过程,及其陆生植被系统的响应及演化过程是研究地质时期全球变化的重点问题,本文通过对华北地区北部LN1钻孔的121个高质量孢粉数据重建了过去3 Ma以来的区域植被演化过程。研究结果显示,区域植被经历了4个主要发展过程,约3~2 Ma气候相对温暖湿润,主要为以松、桦、栎、胡桃、榆等组成的落叶阔叶林;约2 Ma,区域植被急剧变化,主要表现为针叶林扩张,阔叶林比例的减少,在2~1. 2 Ma转变为以松、云杉、桦为主的针阔叶混交林。在中更新世全球气候转型期,区域植被再次发生迅速改变,在约1. 2~0. 7 Ma转变为稀树的灌丛草原,0. 7 Ma以后区域气候进一步干旱化,在最近0. 7 Ma内区域环境转变为典型草原为主的植被景观。区域的植被变化反映了华北平原区近3 Ma以来整体上呈现出干旱化与寒冷化的趋势,其中2. 0 Ma,1. 2 Ma, 0. 7 Ma气候事件最为突出。上述结果反映了华北地区植被的演变过程及季风降水的逐渐减少与北极冰盖在近3 Ma以来的迅速扩张期同步对应。 相似文献
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Quantification of the northern Italy Pliocene climate from pollen data: evidence for a very peculiar climate pattern 总被引：1，自引：0，他引：1
SÉVERINE FAUQUETTE ADELE BERTINI 《Boreas: An International Journal of Quaternary Research》2003,32(2):361-369
A climatic reconstruction has been carried out on the Stirone pollen sequence (northern Italy), covering the Pliocene period from the Zanclean to the early Gelasian (˜5.1 to ˜2.2 Ma). Despite the existence of a number of hiatuses, the section provides a clear picture of the vegetation and climatic evolution during this time interval, which includes the first glacial-interglacial cycles of the Northern Hemisphere. The climate of this period has been quantified using the 'Climatic Amplitude Method' developed for the Neogene, and five climatic parameters have been estimated. The results show that at the beginning of the Pliocene and during the interglacial periods the climate was warm and humid (mean annual temperature from 16 to 20°C, mean annual precipitation from 1100 to 1500–1600 mm), similar to that found elsewhere in the northwestern Mediterranean area. However, during the first glacial periods the reconstructed climate differs from that found at other Mediterranean sites: the mean annual temperature, the temperature of the warmest and coldest months show lower values than those found during the lower Pliocene, but no marked reductions are observed in the annual precipitation, allowing the continuous presence of a forested environment. These results are in agreement with the hypothesis that from at least the Upper Pliocene the Po region has been a special region from the point of view of both vegetation and climate. The difference is particularly marked during the earliest glacial phases in northern Italy. 相似文献
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Eco-environmental effects of the Qinghai-Tibet Plateau uplift during the Quaternary in China 总被引：4，自引：0，他引：4
The Qinghai–Tibet Plateau uplifted >3000 m in the Quaternary period. The average rate of uplift was 1–1.1 mm/year. The uplifting
has remolded the geomorphology of China. The landform in China was changed from west-low and east-high to west-high and east-low
in three steps. The Qinghai-Tibet Plateau uplift is an important factor that affected the climate and the environment of China
in the Quaternary period. It controls atmospheric circulation and climatic change in Asia and even the northern hemisphere,
by dividing the westerlies into two branches: south and north. The plateau gradually became a heat source in summer and a
cold source in winter. The uplift had a decisive effect on the formation of the East-Asia monsoon, which increased the climatic
differences between the glacial period and the interglacial period. The climate and environment of China are characterized
by the influences of the plateau uplift. The east of China became the south-east monsoon area, whereas the south-west became
the south-west monsoon area and the north-west turned into an arid inland region. The Gobi and large-scale deserts that formed
in the inland basins are ceaselessly extending. The climate of northern China became more arid as the Qinghai-Tibet Plateau
continued to uplift. The Plateau uplift affected glacial evolvement and loess formation, and propelled the migration of cold-
and warm-blooded animals, which differed from other regions of the world at the same latitude.
Received: 30 August 1999 · Accepted: 18 April 2000 相似文献