Comparison of methods to determine the anthropogenic CO₂ invasion into the Atlantic Ocean     

R. WANNINKHOF  S. C. DONEY  T.-H. PENG  J. L. BULLISTER  K. LEE  R. A. FEELY 《Tellus. Series B, Chemical and physical meteorology》1999,51(2):511-530

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Imbricate thrust stack model for the formation of glaciotectonic rafts: an example from the Middle Pleistocene of north Norfolk, UK   总被引：1，自引：0，他引：1  

HELEN BURKE  EMRYS PHILLIPS  JONATHAN R. LEE  IAN P. WILKINSON 《Boreas: An International Journal of Quaternary Research》2009,38(3):620-637

In this article, we present a glaciotectonic model for raft emplacement based on a study of large-scale and small-scale deformation structures associated with the accretion of chalk rafts at three Middle Pleistocene sites on the north Norfolk coast, eastern England. Detailed structural measurements taken from the three localities indicate an overall sense of ice movement and raft emplacement towards the south/southeast, suggesting a source area for the rafts located to the north of the present Norfolk coast in the offshore area of the North Sea. Provenancing of the chalk rafts, based on analysis of the foraminifera, also indicates a northern nearshore provenance for the chalk. Mechanisms for the detachment, transport and accretion of the rafts are explored, and it is concluded that pressurized pore water played an important role in all three phases. An imbricate thrust stack model of glaciotectonic raft generation is presented, with the structural history of raft emplacement explained by the geometric relationships between the large-scale basal shear planes and associated deformation structures within adjacent preglacial and glacial sediments.  相似文献   

贵州省遵义市降水中低分子有机酸对自由酸度的贡献   总被引：1，自引：0，他引：1  

江伟  李心清  曾勇  黄荣生  谭凌  彭艳  闫慧  程建中 《地球化学》2009,38(4):351-357

贵州省遵义市是我国酸雨高发地区,研究遵义降水中有机酸对自由酸度的贡献是认识遵义市有机酸地球化学循环和酸雨机制的重要内容。在遵义市中心城区进行了一年的降水采集,并利用离子色谱法和原子吸收光谱法对主要阴离子（包括无机和有机阴离子）和阳离子进行了测定。结果显示,年均pH值为4．11（范围3．12～6．04）,pH〈5．6的样品占93．1％,说明遵义市酸雨污染仍然严重;单因素方差分析显示四季的pH值存在显著差异（P〈0．05）,表明遵义市降水酸化程度具有显著的季节性特征;甲酸和乙酸的雨量加权平均值分别为9．29umol／L和6．47umol／L,检出率分别为98．68％和93．42％,表明有机酸在降水中广泛存在;应用热力学理论计算了有机酸对降水自由酸度的贡献量,发现在pH〈5的遵义降水中甲酸和乙酸对自由酸度的平均贡献量分别为14．79％和3．66％,表明有机酸对降水自由酸度具有重要贡献;对比显示,遵义市的有机酸贡献量低于边远地区,这与遵义市降水的低pH值和高无机酸度有关;四季的有机酸贡献量大小为：春季（31．95％）〉夏季（26．16％）〉冬季（11．17％）〉秋季（8．02％）,可见有机酸对自由酸度的贡献量存在明显的季节性变化。在低酸度和低水温的春季降水中,由于人类活动或有机物质的燃烧所释放的大量有机酸（如汽车尾气的排放、燃煤的燃烧）,促使有机酸对降水自由酸度的贡献量最高;其次是在低酸度和强降雨的夏季;而在低酸度的秋季和冬季,有机酸对酸度的贡献量相对最低。  相似文献   

Underplating of Mesozoic Mantle-derived Magmas in Tongling, Anhui Province: Evidence from Megacrysts and Xenoliths   总被引：1，自引：0，他引：1  

LEE Hyunkoo 《《地质学报》英文版》2004,78(1):131-136

Lithological observations and mineralogical analyses on pyroxene and hornblende megacrysts and pyroxene and hornblende cumulates in xenoliths in the Mesozoic plutons of the Tongling region, Anhui Province, provide evidence for the magmatic underplating of mantle-derived alkali-olivine basalt at circa 140 Ma. The pyroxene and hornblende megacrysts and cumulates were formed through the AFC process at depths ranging from 27 to 35 km.  相似文献   

静压桩残余应力的长期观测性状     

俞峰  谭国焕  杨峻  李启光 《岩土力学》2011,32(8):2318-2324

静压桩施工过程中,可能会沿桩身形成很大的残余应力。通过在砂性土中1根长约26 m静压桩的原位试验,观测了沉桩结束后的残余应力在后续的循环载荷试验、3根邻桩顺次压入、第2次载荷试验以及较长静置期内的长期变化情况,试验历时约212 d。结果显示,循环载荷试验加载水平与循环次数的增加会造成残余应力的进一步累积。邻桩压入使既有桩残余压应力减小,与邻桩即时贯入深度一致的桩身残余应力测点受其影响最明显。桩身残余应力在长时间内会逐步消散至某一稳定值,其时间效应主要与砂性土的蠕变有关,它使得桩周土的土拱效应减弱,并使桩端土的接触压力减小。  相似文献   

西天山两侧前陆盆地晚新生代沉积特征及构造意义   总被引：5，自引：1，他引：4  

王永  李德贵  王彦斌  李建成 《新疆地质》2000,18(3):245-251

天山两侧前陆盆地晚新生代地层发育,沉积厚度较大。盆地沉积序列的韵律性反映了天山造山带的构造演化历史。晚新生代沉积特征及孢粉组合表明,中新世一上新世一早更新世碎屑岩不稳定组分明显增加,阔叶植物花粉含量减少、耐干地喜早的蒿、藜等显著增加,反映天山活动性增强,上新世晚期天山强烈隆升,天山两侧前陆盆地上新世晚期开始出现磨拉石建造,由于山体隆升造成的大气环流改变,天山两侧盆地封闭性增强,大陆性气候流改变,天  相似文献   

An englacial image and water pathways of the Fourcade glacier on King George Island, Antarctic Peninsula, inferred from ground-penetrating radar     

LEE Joohan  KIM Ki Young  HONG Jong Kuk  JIN Young Keun 《中国科学:地球科学(英文版)》2010,(6)

The distribution of small fractures and water content of the Fourcade glacier on King George Island, Antarctica, was investigated in November 2006 and December 2007 by two ground-based (470-and 490-m-long profiles) and one helicopter-borne (470-m-long profile) ground-penetrating radar (GPR) surveys using 50-, 100-, and 500-MHz antennas. Radar images in the pre-migrated GPR sections are characterized by a smooth ice surface and irregular bed topography, numerous diffraction hyperbolas in the ice and at the g...  相似文献   

Aqueous alteration in the matrix of the Vigarano (CV3) carbonaceous chondrite     

Martin R. LEE  Robert HUTCHISON  Andrew L. GRAHAM 《Meteoritics & planetary science》1996,31(4):477-483

Abstract The matrix of Vigarano, a meteorite which belongs to the reduced subgroup of the CV3 chondrites, contains small amounts (<10%) of ferrihydrite and smectite. These hydrous minerals occur together as fine fibrous intergrowths between anhydrous silicate and oxide grains. Coarser crystals of ferrihydrite fill fractures that cut matrix minerals, and smectite also lines narrow channels within olivine grains. These channels may have formed by preferential alteration of olivines along (100)-parallel defects. Formation of ferrihydrite and smectite in the matrix of Vigarano was the result of mild aqueous alteration in a low-temperature (<150 °C), oxidising parent body environment. Partial equilibration of matrix olivines indicates that alteration was followed by thermal metamorphism with a peak temperature of 400–500 °C. Mineralogically similar alteration products, which also were formed by parent body processes, have previously been described from the matrices of four CV meteorites: Bali, Grosnaja, Kaba and Mokoia, all of which belong to the oxidised subgroup. This discovery of the products of oxidative aqueous alteration in Vigarano has important consequences for understanding the chemical and thermal history of the CV class of meteorites.  相似文献   

The Petrology and Geochemistry of Volcanic Rocks on Jeju Island: Plume Magmatism along the Asian Continental Margin   总被引：2，自引：0，他引：2  

TATSUMI  YOSHIYUKI; SHUKUNO  HIROSHI; YOSHIKAWA  MASAKO; CHANG  QING; SATO  KEIKO; LEE  MOON WON 《Journal of Petrology》2005,46(3):523-553

The incompatible element signatures of volcanic rocks formingJeju Island, located at the eastern margin of the Asian continent,are identical to those of typical intraplate magmas. The sourceof these volcanic rocks may be a mantle plume, located immediatelybehind the SW Japan arc. Jeju plume magmas can be divided intothree series, based on major and trace element abundances: high-aluminaalkalic, low-alumina alkalic, and sub-alkalic. Mass-balancecalculations indicate that the compositional variations withineach magma series are largely governed by fractional crystallizationof three chemically distinct parental magmas. The compositionsof primary magmas for these series, using inferred residualmantle olivine compositions, suggest that the low-alumina alkalicand sub-alkalic magmas are generated at the deepest and shallowestdepths by lowest and highest degrees of melting, respectively.These estimates, together with systematic differences in traceelement and isotopic compositions, indicate that the upper mantlebeneath Jeju Island is characterized by an increased degreeof metasomatism and a change in major metasomatic hydrous mineralsfrom amphibole to phlogopite with decreasing depth. The originalplume material, having rather depleted geochemical characteristics,entrained shallower metasomatized uppermost mantle material,and segregated least-enriched low-alumina alkalic, moderatelyenriched high-alumina alkalic, and highly enriched sub-alkalicmagmas, with decreasing depth. KEY WORDS: Jeju Island; magma genesis; mantle plume; subcontinental mantle  相似文献   

四层模式热成风适应   总被引：1，自引：1，他引：1  

陈秋士  励名德 《气象学报》1964,34(3):253-270

本文用四层模式分析了热成风适应。在适应过程中将发生四种波速不同的惯性波来调节流场和温度场的关系。它们的前阵面的速度分别为306米/秒,114米/秒,36.2米/秒,19.2米/秒。层次愈高,快速惯性波的作用愈大;惯性外波在750毫巴以下才有它的重要性。 计算指出:大气中辐合辐散以及垂直运动在垂直方向上互相迭置的现象,是一定条件下热成风适应的结果。本文计算了各种情况的初始条件下温度场和气压场的相互调整。例如375毫巴上单纯非地转风的流场的反气旋涡旋,适应后可建立起对流层暖性、平流层是冷性的高压系统。将初始非热成风的暖温度中心,放在对流层下层和放在对流层中层适应后的结果将不一样。前者只能在对流层下层形成一浅薄的热低压,而后者可在对流层上层建立起一个强大的反气旋,甚至一直影响到平流层。最后,结合气旋发展时所产生的非热成风的特点,讨论了它们的适应。  相似文献