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991.
Based on the determination of composition of volcanic volatiles and petrologic estimation of the total mass of volatiles erupted,
we showed important advances in the study of the impact of Mesozoic and Cenozoic volcanic activities on paleo-environmental
changes in China. The volcanic activities include western Liaoning and Zhangjiakou Mesozoic intermediate-acidic explosive
eruptions, southern Tibet and Shanwang Cenozoic volcanism, and Mt. Changbai volcanic eruption around one thousand years ago.
The paper predominantly discusses the earth’s surface temperature changes, ozone depletion, acidic rain formation and mass
mortalities of vertebrate induced by the Mesozoic and Cenozoic volcanism in China.
__________
Translated from Bulletin of Mineralogy, Petrology and Geochemistry, 2007, 26(4): 319–322 [译自: 矿物岩石地球化学通报] 相似文献
992.
Hualing Wei Nianqiao Fang Xuan Ding Lanshi Nie Xiuming Liu 《Frontiers of Earth Science》2008,2(2):162-169
This paper presents pelagic records of planktic foraminifera, as well as data of stable isotope stratigraphy and carbonate
stratigraphy since 3.5 Ma B.P. from site ODP758 in the Ninetyeast Ridge of the Indian Ocean. Based on these data, manifestations
and related mechanisms of major tectonic and environmental events such as the rapid uplift of the Himalaya Mountains, “middle
Pleistocene climatic transition” and “mid-Brunhes dissolution event” in the region are discussed. According to the analysis
and comparison of various indices and changes in terms of foraminifera assemblage, paleotemperature, paleosalinity and themocline
from site ODP758, the authors deduce that the paleoclimatic changes might correlate with the mid-Pleistocene transition at
1.4–1.7 Ma B.P. The changes of CaCO3, mass accumulation rates (MAR) of CaCO3 and non- CaCO3 MAR indicate that the loaded terrigenous sediments increased at 1.7 Ma, which is in agreement with the uplift history of
the Qinghai-Tibet plateau as shown by the available data. The last two changes coincide with the uplift of the Qinghai-Tibet
plateau, hence they are called “Qinghai-Tibet movement” (1.7 Ma), and the “Kunlun-Yellow River movement” (1.2–0.6 Ma). The
changes of the CaCO3 content, coarse fraction (> 150 μm) content and planktonic foraminifera biostratigraphy show that strong dissolution of abyssal
CaCO3 occurred in the study region during 0.5–0.4 Ma. The event was consistent with the “mid-Brunhes dissolution event” in the
sedimentary records of the Atlantic Ocean, Pacific Ocean, Indian Ocean and Nansha sea area of the South China Sea.
__________
Translated from Geological Bulletin of China, 2007, 26(12): 1627–1632 [译自: 地质通报] 相似文献
993.
Wenguang Yang Hongbo Zheng Ke Wang Xin Xie Guocheng Chen Xi Mei 《Frontiers of Earth Science》2008,2(2):170-176
Sediments with high sedimentation rate at site MD05-2905 in the Northeastern slope of the South China Sea provide unique materials
for a high-resolution study on the paleoenvironment. Based on precise dating of AMS 14C, grain size analysis of terrigenous debris at core MD05-2905 was conducted after organic matter, biological carbonate and
biogenic opal were removed. The results show that 15.5–63.5 μm coarse grain size ingredients may indicate East Asian winter
monsoon changes and that 2–9 μm fine grain size ingredients may be used as a proxy of evolution of the East Asian summer monsoon.
The results of grain size analysis, which suggest East Asian monsoon intensity, reveal that a winter monsoon dominated the
glacial regime and a summer monsoon dominated the Holocene regime. It was also shown that the summer monsoon increased gradually,
experienced several abrupt changes and reached a culmination in the early Holocene (11200–8500 a B.P.) since 36 ka. Controlled
by precession periodicity, it may be related with the amount of solar radiation at the highest stage, which needs further
study.
__________
Translated from Advances in Earth Science, 2007, 22(10): 1012–1018 [译自: 地球科学进展] 相似文献
994.
In northern Jiangsu coastal zone area, Guanhe River is the biggest river and has the best navigation conditions among rivers
which flow into the Yellow Sea. The grain sizes show gradual increase from the high intertidal zone to lower intertidal zone.
The heavy metal values have slight changes along both sides of the river mouth, but show an evident change perpendicular to
the tidal flat. In the latter case, they show a good correlation with grain size fluctuation, that is, the heavy metal values
gradually decline when the grain size increases from the high intertidal zone to the lower intra-tidal zone. Analyses of the
heavy metal elements show that on the Guanhe estuary surface sediment, the content of the elements Hg, As and Cu is above
background values; Pb and Zn contents are rather close to the background values; and Cd content is less than the background
values. The element Hg comes out to be harmful in a medium level to ecological environment, while the elements of Cr, As,
Cu, Pb, Zn and Cd fall in a safe range of MPL. On the whole, Guanhe estuary tidal flat is not very harmful to the ecology
in terms of the heavy metals.
__________
Translated from Marine Geology & Quaternary Geology, 2007, 27(5): 23–32 [译自: 海洋地质与第四纪地质] 相似文献
995.
996.
新疆西天山艾肯达坂以东出露一大套陆相磨拉石建造,厚度约2 800 m,角度不整合在含煤系的石炭系科古琴山组之上,主要岩性是砾岩、粗砂岩夹少量细砂岩、粉砂岩.由于其中化石稀少,时代难以确定.1971年新疆地质局区域地质测量大队完成的1:20万小布鲁斯台幅称其为早二叠世下亚组和上亚组.作者于2004年在此处进行1:5万区域地质矿产调查时发现了一层灰岩,其中找到了蚌壳等淡水动物化石,确定其时代为晚二叠世,并将其划归为铁木里克组.铁木里克组经受了二叠纪末期的构造运动,被产状平缓的侏罗系中下统水西沟组角度不整合覆盖,三叠系缺失,以此来确定本回造山时间应在二叠纪末结束. 相似文献
997.
998.
利用一组标准正交化的参考向量得到一个可能匹配区域,排除了绝大部分不可能匹配的样本,从而大大提高光谱预选筛分的速度;同时介绍了一种平衡速度与精度的编码替代算法.实验证明:压缩影像的目视效果较好,未产生边缘模糊及条带现象;采用自动目标生成方法(ATGP)从样本集中提取端元并进行光谱角度制图,其效果令人满意. 相似文献
999.
基于天池煤矿地质勘探资料,结合区域构造背景研究了矿井地质构造特征及形成机制。天池煤矿构造属简单构造,地层总体呈走向北东、倾向北西的单斜构造,矿井内褶皱发育程度较低,断层以正断层为主,其次为低角度逆掩断层。陷落柱分布较为杂乱,成群出现,常见于褶皱轴部。自三叠纪末期开始一直受到区域构造活动的控制作用,印支期受SN向的挤压,形成了一些近EW向的构造;燕山期经历两期NWW--SEE向挤压使井田内地层及煤层主体呈NE走向;喜山早期的NE—SW向挤压,导致NE向断层的性质发生转变;上新世开始表现为区域上的伸展作用。 相似文献
1000.
硅化木,又称树化石、木化石,无论它的内在品质多么优良,依然是“化石”身份,不能把优质硅化木称为“树化玉”。因为按照所谓“化”的含义,“树化玉”就只能解释为“玉”变成了“树”,或解释为“玉”具有了“树”的一些性质和特征,这显然是不对的。再如,古生物化石也不能称为“古生物化玉”。所以将硅化木称“树化玉”是欠妥的。 相似文献