桂东南地区大容山-十万大山花岗岩带SHRIMP锆石U-Pb定年

桂东南地区大容山-十万大山花岗岩以含过铝质矿物为特征,是华南地区显生宙典型的S型花岗岩岩带.虽然前人对该岩带的侵入年代进行了许多研究工作,认为其为海西-印支期产物,但由于以往测年方法和技术的一些局限性,对于华南是否存在海西期花岗岩一直存在不同意见.本文对大容山、旧州岩体和台马岩体进行了高精度错石SHRIMP定年,3个岩体的形成年龄分别为233±5 Ma、230±4 Ma和236±4 Ma,说明该花岗岩岩带形成于印支期,是由推覆构造引起地壳增厚、地壳重熔形成的.     

新疆准噶尔盆地南缘郝家沟组和八道湾组底部孢粉组合及三叠系-侏罗系界线

新疆乌鲁木齐郝家沟剖面郝家沟组及八道湾组底部的孢粉分为 3个组合。即郝家沟组的 Alisporites-Chordasporites- Chasmatosporites组合和 Aratrisporites- Alisporites- Chasmatosporites组合以及八道湾组底部的Asseretospora- Dictyophyllidites- Cycadopites组合。前两个组合主要由常见或仅见于三叠系的属种组成 ,时代属于晚三叠世无疑 ;后一组合中前期分子大量消失 ,蕨类孢子迅速崛起 ,反映植物群出现显著变化 ,其中常见和仅见于晚三叠世的分子不复存在 ,主要成分为晚三叠世到侏罗纪常见的分子 ,具有晚三叠世到早侏罗世的过渡特点 ,时代趋向于早侏罗世。因此 ,本文提出三叠系—侏罗系的界线划在郝家沟组之顶是合适的。     

新疆和田玉岩石学特征及其扫描电镜研究

新疆和田玉产于塔里木盆地之南昆仑山的变质软玉矿床, 该矿床是由镁质大理岩与中酸性岩浆岩接触交代而形成。通过对和田玉的岩石矿物学研究表明和田玉主要由富钙富镁的透闪石矿物构成,其化学组分中Ｍｇ２＋ ／（Ｍｇ２＋ ＋ Ｆｅ２＋ ）比值均大于０．９。对和田玉岩石薄片镜下观察发现,和田玉是由透闪石微晶－隐晶质集合体构成,其颗粒越细小, 交织结构越致密,其质地就越细腻润泽。通过对和田玉的扫描电镜的观察分析, 探讨了和田玉高韧度主要与其特殊的交织结构所产生的粒间绞合力有关     

西藏西部冈仁波齐花岗闪长岩锆石SHRIMP U-Pb定年及其地质意义

冈底斯岩带西段冈仁波齐岩体斑状花岗闪长岩中的锆石SHRIMPU-Pb年龄测定结果为48.3Ma±1.5Ma,该年龄反映了冈仁波齐花岗闪长岩体的侵位或结晶年龄,属于喜马拉雅期,相当于中始新世。岩体的形成时间略晚于印度-欧亚大陆初始碰撞的时间,为两大陆碰撞作用过程中的产物,属同碰撞花岗岩。     

高岭石—聚丙烯腈夹层复合物的制备

作者通过XRD和IR等手段研究了高岭石－聚丙烯腈夹层复合物的形成过程。通过对高岭石／DMSO（二甲亚砜）、高岭石／乙酸铵等中间复合物的置换反应，成功地将丙烯腈单体引入高岭石层间。XRD谱表明高岭石层间被插入有机分子后，其层间距增大；IR谱显示有机分子与高岭石的外羟基可能以氢键的形式相互作用。在有引发剂的存在下，实现了丙烯腈单体在高岭石层间的聚合。     

内蒙古东部陆西凹陷中北部上侏罗统层序地层格架及体系域特征分析

对内蒙古东部开鲁盆地陆西凹陷地质和地球物理资料的综合研究表明，上侏罗统沉积以温湿气候条件下的粉、细砂岩及泥岩为特征，其沉积序列可以被划分成周期为3-5 Ma的5个沉积层序，各沉积层序之间均为不整合面或与之相关的整合面。沉积层序格架和构型主要受控于构造活动、气候和物源供给。各沉积层序的展布也受盆地结构和断裂差异活动的影响，表现出南厚北薄的地层展布特征。由于在马北斜坡存在地形或断裂坡折带，故可将一个沉积层序细分成低位、湖侵和高位体系域。在明确首次和最大湖泛面基本特征的基础上，重点叙述了层序B低位、湖侵和高位体系域的近岸水下扇、扇三角洲等沉积体系特征和层序构型主控因素。对有利烃源岩、储层和盖层等成藏基本条件进行分析后，指出层序C西绍根断层下降盘的近岸水下扇和位于坡折带之下的浊积扇是寻找岩性圈闭的有利地区。     

基于Gauss-FFT技术高精度三维磁异常ΔT正演

三维磁异常傅里叶正演,能够计算整个场源区域内与磁化率分布网格一致的三维磁异常。通过三维傅里叶变换推导了长方体三维磁谱表达式,当源体埋藏较深或者位于反演区域边缘时,标准FFT正演异常场由于强制周期化,边界震荡等原因,使得正演结果发生较大的畸变,为了减少标准FFT算法引起的误差,引入了3DGauss-FFT技术用于三维磁异常频率域正演。通过简单的模型正演验证,从计算时间、计算精度以及内存需求上与空间域算法及标准3DFFT算法进行比较,结果表明,3DGauss-FFT磁异常正演相比于标准FFT算法在计算精度上有很大提升,显著降低了标准3DFFT由于自身缺陷引起的误差,且在运行时间上,4点3DGauss-FFT磁异常正演算法相对于空间域算法降低了三个数量级,但内存需求有所增加,证明了3DGauss-FFT正演方法在磁异常正演方面的高效性以及准确性。     

A New Genus of Fossil Cycads Yixianophyllum gen. nov. from the Late Jurassic Yixian Formation, Western Liaoning, China

A new genus of fossil Cycads, Yixianophyllum gen. nov., is reported here. The specimens were collected from the southern hill of Jinjiagou village, Toudaohezi Town, Yixian County, western Liaoning Province, China. The fossil plant-beating bed belongs to the lower part, the Zhuanchengzi bed, of the Upper Jurassic Yixian Formation （Yixianian）. The new genus in leaf shape, venation and epidermal structure shows a transitional form between Mesozoic Cycads （Ctenis, Nilssonia） and modem Cycads （Stangeria and Encephalartos）. Since the features of these specimens differ from any known genera of Cycads, a new generic name Yixianophyllum is proposed for these leaves. Typical species, Yixianophyllum jinjiagouense gen. et sp. nov. is described here. A supposed evolutionary tendency of Cycadean leaf-forms with Taeniopteris-type is discussed.     

Driving Mechanism of Cultivated Land Transition in Yantai Proper,Shandong Province,China

Cultivated land transition and its driving mechanism are the hotspots among studies on land use change. In this study, we constructed a framework to study the driving mechanism of cultivated land transition from the quantitative perspective. Based on the vector data of land use in 1990, 2000 and 2009 of Yantai Proper, Shandong Province China, 11 explanatory variables were chosen from two aspects: the elevation, slope, cost distance to major water area and cost distance to minor water area, which presented physical factors; cost distance to district center, cost distance to town center, cost distance to city expansion center, cost distance to major roads, cost distance to city roads, cost distance to county roads and cost distance to rural roads, which presented the socio-economic factors. Combined with spatial analysis tools and Logistic regression analysis model, we construct Logistic regression analyses with four objectives that were urban construction land, rural residential land, orchard and other lands. The results show that, cost distance to district center, cost distance to town center, cost distance to city expansion center and cost distance to city roads are the significant explanatory variables for the transition of cultivated land into urban construction land. The main explained factors on the transition of cultivated land into rural residential land are slope, cost distance to town center, cost distance to county roads and cost distance to rural roads. Slope, cost distance to minor water area, cost distance to town center, cost distance to county roads and cost distance to rural roads are the significant explanatory variables for the transition of cultivated land into orchard land. Elevation, slope, cost distance to major water area and cost distance to minor water area are the main explanatory variables on the transition of cultivated land into other land uses.