Decadal to monthly timescales of magma transfer and reservoir growth at a caldera volcano

Caldera-forming volcanic eruptions are low-frequency, high-impact events capable of discharging tens to thousands of cubic kilometres of magma explosively on timescales of hours to days, with devastating effects on local and global scales. Because no such eruption has been monitored during its long build-up phase, the precursor phenomena are not well understood. Geophysical signals obtained during recent episodes of unrest at calderas such as Yellowstone, USA, and Campi Flegrei, Italy, are difficult to interpret, and the conditions necessary for large eruptions are poorly constrained. Here we present a study of pre-eruptive magmatic processes and their timescales using chemically zoned crystals from the 'Minoan' caldera-forming eruption of Santorini volcano, Greece, which occurred in the late 1600s BC. The results provide insights into how rapidly large silicic systems may pass from a quiescent state to one on the edge of eruption. Despite the large volume of erupted magma (40-60 cubic kilometres), and the 18,000-year gestation period between the Minoan eruption and the previous major eruption, most crystals in the Minoan magma record processes that occurred less than about 100 years before the eruption. Recharge of the magma reservoir by large volumes of silicic magma (and some mafic magma) occurred during the century before eruption, and mixing between different silicic magma batches was still taking place during the final months. Final assembly of large silicic magma reservoirs may occur on timescales that are geologically very short by comparison with the preceding repose period, with major growth phases immediately before eruption. These observations have implications for the monitoring of long-dormant, but potentially active, caldera systems.     

Discovery of a flank caldera and very young glacial activity at Hecates Tholus, Mars

The majority of volcanic products on Mars are thought to be mafic and effusive. Explosive eruptions of basic to ultrabasic chemistry are expected to be common, but evidence for them is rare and mostly confined to very old surface features. Here we present new image and topographic data from the High Resolution Stereo Camera that reveal previously unknown traces of an explosive eruption at 30 degrees N and 149 degrees E on the northwestern flank of the shield volcano Hecates Tholus. The eruption created a large, 10-km-diameter caldera approximately 350 million years ago. We interpret these observations to mean that large-scale explosive volcanism on Mars was not confined to the planet's early evolution. We also show that glacial deposits partly fill the caldera and an adjacent depression. Their age, derived from crater counts, is about 5 to 24 million years. Climate models predict that near-surface ice is not stable at mid-latitudes today, assuming a thermo-dynamic steady state. Therefore, the discovery of very young glacial features at Hecates Tholus suggests recent climate changes. We show that the absolute ages of these very recent glacial deposits correspond very well to a period of increased obliquity of the planet's rotational axis.     

Climate change, social unrest and dynastic transition in ancient China

The alternation of war and peace accompanied bydynastic transitions was shown to be the rhythm of socialdevelopments throughout Chinese history. Western schol-ars attempted to use the “Dynastic Cycle” theory to expli-cate why the socio-economic development in China wasembedded in such a historical rhythm[1—4]. Dynastic cycletheory states that any dynastic rise-and-fall, social ac-cord-and-discord, and economic upturn-and-downturn areclosely related to the trend of societal development andt…     

Granite magma formation, transport and emplacement in the Earth's crust

The origin of granites was once a question solely for petrologists and geochemists. But in recent years a consensus has emerged that recognizes the essential role of deformation in the segregation, transport and emplacement of silica-rich melts in the continental crust. Accepted petrological models are being questioned, either because they require unrealistic rheological behaviours of rocks and magmas, or because they do not satisfactorily explain the available structural or geophysical data. Provided flow is continuous, mechanical considerations suggest that--far from being geologically sluggish--granite magmatism is a rapid, dynamic process operating at timescales of < or = 100,000 years, irrespective of tectonic setting.     

The thermal history of the miarolitic granite at Xincun, Fujian Province, China

The thermal history of the late Mesozoic miarolitic granite has been studied based on zircon U-Pb dating, whole rock Rb-Sr dating and K-Ar dating of muscovite, biotite and K-feldspar from the same rock sample. From the beginning of zircon crystallization to the closure of K-Ar system of biotite, the granite body had a slow cooling rate (11.0℃/Ma) and an ascending rate (0.07 mm/a). From the end of this stage to the closure of K-Ar system of K-feldspar, the granite body increased its cooling rate (45℃/Ma) and ascending rate (0.36 mm/a). The thermal history of the Xincun granite with a slow cooling rate at the early stage and a fast cooling rate at the late stage may have been related to the fact that the Fujian coastal area had very high geothermal gradient in the late Mesozoic and evident decrease in geothermal gradient in the early Cenozoic.     

古田溪三级电站坝基及扬压力异常情况分析

对我国５０年代末期有代表性的边勘测，边设计，边施工的“三边”工程之一－古田溪三级电站运行３０多年来，其大坝基础状况及部分扬压力孔发生异常等情况作了分析研究，提出一些建议，对处理类似的三边工程具有实际意义。     

番禺隆起新近系层序、沉积演化与地层圈闭

综合分析钻井、地震等资料,将区内新近系划分为14个三级层序,每个层序又可以海泛面为界细分为3～5个四级层序或体系域.层序界面和水进面与浮游有孔虫的丰度和分异度变化有密切关系.结合钻井约束的地震沉积学分析,可识别出低位域(辫状河)三角洲、河流三角洲、浅海陆棚等沉积体系.地层属性分析揭示了三角洲前缘沉积在平面上特有的环状结构.以四级层序为地层单元的沉积相平面编图可很好地反映不同体系域的沉积相演化.区内的层序结构和沉积相带演化主要受到海平面变化的控制.区内存在5种潜在的岩性地层或构造-地层圈闭,由断裂坡折带控制的低位域三角洲砂体已由勘探证实可形成重要的构造-地层油气藏.     

不同潮型和风况下青草沙水库取水口盐水入侵来源

本文应用2013年12月和2014年2月青草沙水库取水口实测盐度和数值模式计算的流速流向,分析水库取水口盐水入侵的来源.2013年12月枯季在一般径流量和风况的情况下,大潮、大潮后中潮和小潮前期水库取水口盐水来源于上游的北支倒灌,小潮中后期、小潮后中潮盐水入侵来源于北港下游外海的盐水入侵.观测资料发现2014年2月长江河口盐水入侵是近几十年来发生过的最严重盐水入侵事件,导致青草沙不宜取水的时间达到23 d,对上海的安全供水造成了严重威胁.2014年2月枯季在一般径流量和持续偏北大风15 d情况下,所有4个潮型中青草沙水库取水口盐水均来自北港外海的正面入侵.     

塔里木盆地塔北隆起西部圈闭类型、分布及空间组合规律

围绕塔北西部碳酸盐岩和碎屑岩这两大类勘探目标,采用"成因分类法"将塔北西部已经发现的圈闭划分为4大类8亚类.在此基础上,对不同圈闭类型分布的主要层位及平面展布特征做了分析.划分了4个圈闭形成期,并分析了在不同构造演化阶段,构造运动和沉积环境对不同圈闭类型的控制作用.归纳了塔北西部圈闭的空间组合规律.     

沙雅隆起白垩系卡普沙良群层序地层与沉积模式

综合运用钻井、测井和地震资料,对塔里木盆地沙雅隆起白垩系卡普沙良群进行了层序地层及沉积相研究。沙雅隆起处于库车前陆盆地的前隆带和隆后坳陷,卡普沙良群对应于一幕逆冲构造活动,其内细分的3个层序（SQ1-SQ3）对应前陆盆地的不同演化阶段。SQ1处于逆冲构造活动的初始期,低位体系域占主导,前隆带中部剥蚀,其两侧斜坡发育来自该剥蚀区的扇三角洲、辫状河三角洲沉积,隆后坳陷则发育来自前隆带及盆地腹部的三角洲沉积;SQ2处于逆冲构造活动增强期,湖侵体系域相对发育,前隆带整体沉降至水下,以滨浅湖沉积为主,隆后坳陷则主要发育曲流河三角洲沉积;SQ3处于逆冲构造活动减弱期和停滞期,以高位体系域的相对发育为特征,前隆带和隆后坳陷成为一体,发育曲流河三角洲和辫状河三角洲沉积。     

吉隆盆地构造、环境演化与青藏高原隆升

位于喜马拉雅北麓的晚新生代吉隆断陷盆地,在中新世晚期-上新世沉积了总厚约300m的河湖相地层。根据沉积学、碳氧同位素及控盆构造分析,结合已有的古生物学孢粉学资料,恢复了晚新生代盆地构造控制、沉积环境、气候变动及其演变过程;探讨了构造演化和气候变动两者之间的耦合关系;指出盆地由早期半封闭型断陷湖盆,中期开放型湖盆,向后期封闭型湖盆的演化。     

加拿大萨德伯里奈恩地区镁铁-超镁铁岩体特征及其成矿机制

加拿大萨德伯里(sudbury)地区分布一种成因上与萨德伯里陨石撞击事件无关的岩浆铜镍硫化物矿床。该类矿床的形成受古元古代尼帕辛(Nipissing)镁铁—超镁铁侵入岩套控制,其中以莎士比亚(Shakespeare)矿床和奈恩(Nairn)矿床为典型。奈恩岩体在地表出露Ⅰ号和Ⅱ号两个岩体,呈北东走向岩墙式分布,在深部二者合并为一个整体。奈恩岩体的岩浆分异性良好,从岩体底部至顶部具有明显的岩相分带,下部辉石岩相和中部苏长辉长岩相为主要含矿岩相。辉石岩中发育块状-半块状铜镍硫化物;苏长辉长岩中发育浸染状-星散状铜镍硫化物。奈恩岩体中各岩石单元属于钙碱性系列。根据(Mg/)对(Mg+)/Si变异图、(Mg+Fe)/Ti-Si/Ti图解、(Na₂O+K₂O)对SiO₂变异图、Al₂O₃对SiO₂变异图、FMC图解,奈恩岩体属于镁铁-铁镁质、低铝、弱碱质和低钙(贫钙)岩体。奈恩地区成矿机制概括为四个岩浆演化阶段,第一、第二阶段中的含硫围岩混染作用、双扩散对流作用,对岩浆分异和含硫岩浆的熔离起了重要作用,铜镍硫化物的最终形成主要是在第三和第四阶段完成。     

准噶尔盆地车排子凸起新近系沙湾组重矿物、U-Pb年代学特征及物源分析

综合岩石学特征、砂岩碎屑组分特征、重矿物组合特征和锆石U-Pb年代学特征, 探讨准噶尔盆地车排子凸起新近系沙湾组沙一段的沉积特征和物源演化过程。结果表明, 车排子凸起存在南北双物源体系, 沙一段以粗碎屑沉积为主。在一砂组沉积阶段, 扎依尔山为北部物源区, 发育小规模扇三角洲沉积; 中天山及北天山造山带为南部物源区, 发育辫状河三角洲沉积。在二砂组沉积阶段, 中天山供给减弱, 北天山供给加强, 盆地水体加深, 南部辫状河三角洲前端分布小型滨浅湖滩坝。南部物源变化的主要原因可能是受印度板块和欧亚板块碰撞的远程影响, 天山在新生代中新世中期经历强烈的挤压和抬升过程, 造成北天山隆升, 为车排子凸起提供物源。     

鲁西隆起晚中生代以来北西向正断层特征及物理模拟

鲁西隆起区伸展构造极为发育,通过野外地质调查对隆起区北西向正断层的几何学特征进行研究,采用平衡剖面演化方法,选取横穿该区北西向断层的一条剖面,定量计算正断层横向上和垂向上晚中生代以来各主要构造演化阶段的构造运动学参数,并通过构造物理模拟实验详细解析鲁西隆起区伸展变形过程。研究结果表明,北西向控凹断层在三叠纪后皆发生负反转,晚中生代鲁西隆起受到强烈拉伸,伸展构造主要发生在19~20 km以下的深尺度范围内,断层切割深度加大。断裂带上普遍发育断层角砾岩、碎裂岩及断层泥。古近纪伸展作用以浅层拉伸为主,鲁西伸展量和伸展率最大,伸展作用强烈,对应北西向正断层的活动速率值也达最大值,同时发育大规模、范围广的半地堑。新近纪,伸展率很小,北西向正断层活动性大大减弱,至第四纪,断层几乎不再活动,反映鲁西隆起基本处于稳定。鲁西隆起晚中生代的伸展与华北克拉通构造变革相一致,而新生代的强烈伸展主要受控于太平洋板块与欧亚板块俯冲方向与速度的改变以及印度板块与欧亚板块的碰撞。     

导电高分子聚苯胺热寿命及变温红外光谱的测定

导电高分子聚苯胺的应用依赖于环境的温度.为了测定温度对聚苯胺的影响,首先采用循环伏安法在硫酸介质中电化学合成了导电高分子聚苯胺,然后利用TGA热分析测定了聚苯胺的热分解温度为285.2℃.通过等温热重法计算了材料的热寿命,得到失重5%,7%,10%时的热寿命方程.聚苯胺变温红外的测定结果表明,随着温度的升高,聚苯胺特征吸收波数,由于分子键共轭程度的降低,均向高波数位移.     

重磁电震资料联合反演黔中隆起物性结构

黔中隆起区地形和构造复杂,地震勘探难度大,资料品质受到一定影响.因此,利用大地电磁测深(MT)资料并结合重力和磁力资料,通过联合反演来重点解决研究区下古生界目的层的分布及基本构造特征.在物性研究基础上,建立该区基本的物理一地质模型.利用MT与地震资料的模拟退火约束同步反演技术,对黔中隆起实际采集的MT资料和地震数据进行了处理,并结合重磁力资料进行了顺序反演和综合解释,确定了该区基本的速度、电性、密度和磁性结构,为构造研究提供了全面和可靠的依据,证明了联合反演技术的有效性和实用性.     

hPin1原核表达、纯化及热稳定性研究

利用E．coli BL21原核表达,纯化得到了His-hPin1融合蛋白,并研究了它的热稳定性．在中性条件下进行不同温度处理,SDS-PAGE分析表明,低于40℃处理不会影响His-hPin1的溶解性,50～100℃处理会使其部分变性而沉淀．荧光发射光谱研究表明,未处理的His-hPin1具有339nm的荧光发射峰;热处理使荧光发射峰的位置变化,低于40℃处理对His—hPin1的荧光强度影响较小,50～100℃热处理使HiS-hPin1的荧光强度明显降低．圆二色谱研究表明,热处理对His-hPin1的二级结构有影响,引起α-螺旋含量的明显减少,而无规卷曲增加．以上数据表明hPin1是一个相对热稳定的蛋白．     

煤低温自燃发火的热效应及热平衡测算法

煤在低温自燃发火过程中的热效应是多种多样的,但主要是煤与氧的化学反应热.通过装煤850kg的大型煤低温自燃发火实验台模拟煤自燃过程,根据实验台测定的温度场变化和传热学理论,推导出计算不同温度时松散煤体低温氧化放热强度的热平衡测算法.通过对不同煤样的自燃发火测试,利用该方法推算出不同的煤在相同温度下的放热强度,为煤自燃特性的定量分析及自燃发火预测提供了理论依据.图1,表1,参8.     

Viscosity, thermal diffusivity and Prandtl number of nanoparticle suspensions

Using our reported experimental data of effective thermal conductivity, specific heat capacity and viscosity for CuO nanoparticle suspensions, the corresponding thermal diffusivity and Prandtl number are calculated. With the hard sphere model and considering effects of particle clustering and surface adsorption, the increase of viscosity for nanoparticle suspension observed is explained. It is shown that the effective thermal conductivity will be strongly affected by the formation and correlated spatial distribution of nanoparticle clusters when compared to viscosity in hosting liquid.