基于立方体元的Shear - warp体绘制加速算法

大规模三维地震数据的直接体绘制,是一个计算和数据双重密集型问题.为了提高三维图像的重建效率,提出了一种基于立方体元的Shear- warp地震数据体绘制算法.该算法通过构建立方体元在相邻的体素点之间建立联系;然后根据地震数据的特征对体元进行分类,在绘制过程中通过二叉树索引,快速定位分类结果.通过索引结果,避免了对等值体...     

砂土液化大变形模型在FLAC3D中的开发与应用

通过FLAC3D二次开发平台,在VC++环境下实现了基于砂土液化大变形机制的变动映射中心边界面弹塑性模型的二次开发。基于饱和砂土液化大变形本构理论,该模型符合三维应力空间边界面映射规则,并引入临界状态变量,可实现对不同密度和围压状态下砂土液化大变形分析。针对FLAC3D程序混合离散技术与数据调用模式和模型的体积相容性条件,测试分析了将模型采用不同植入方案的计算稳定性,开发了在FLAC3D混合离散技术下不同子区共享映射中心,进入与离开液化状态保持同步的开发方案,并给出模型开发的关键技术与实施方法。利用开发的模型,对饱和砂土开展了不排水/排水/循环三轴试验与不排水循环扭剪试验模拟,及三维地基的动力反应分析。计算结果表明,模型及所开发程序具有很好的模拟与分析砂土液化后大变形的能力。     

Organic Geochemistry of the Early Jurassic Oil Shale from the Shuanghu Area in Northern Tibet and the Early Toarcian Oceanic Anoxic Event

This paper presents new geological and geochemical data from the Shuanghu area in northern Tibet, which recorded the Early Toarcian Oceanic Anoxic Event. The stratigraphic succession in the Shuanghu area consists mostly of grey to dark-colored alternating oil shales, marls and mudstones. Ammonite beds are found at the top of the Shuanghu oil shale section, which are principally of early Toarcian age, roughly within the Harplocearasfalciferrum Zone. Therefore,the oil shale strata at Shuanghu can be correlated with early Toarcian black shales distributing extensively in the European epicontinental seas that contain the records of an Oceanic Anoxic Event. Sedimentary organic matter of laminated shale anomalously rich in organic carbon across the Shuanghu area is characterized by high organic carbon contents, ranging from 1.8% to 26.1%. The carbon isotope curve displays the δ^13C values of the kerogen (δ^13Ckerogen) fluctuating from -26.22 to -23.53‰ PDB with a positive excursion close to 2.17‰, which, albeit significantly smaller, may also have been associated with other Early Toarcian Oceanic Anoxic Events (OAEs) in Europe. The organic atomic C/N ratios range between 6 and 43, and the curve of C/N ratios is consistent with that of the δ^13Ckerogen values. The biological assemblage,characterized by scarcity of benthic organisms and bloom of calcareous nannofossils (coccoliths), reveals high biological productivity in the surface water and an unfavorable environment for the benthic fauna in the bottom water during the Oceanic Anoxic Event. On the basis of organic geochemistry and characteristics of the biological assemblage, this study suggests that the carbon-isotope excursion is caused by the changes of sea level and productivity, and that the black shale deposition, especially oil shales, is related to the bloom and high productivity of coccoliths.     

粤北大宝山矿区加里东期火山岩的厘定及其地质意义

粤北大宝山矿区一带出露一套与层状Fe-Cu-Pb-Zn矿化紧密共生的层状火成岩。层状火成岩产状与上覆页岩及大理岩和下伏碳质页岩基本一致。本文通过层状火成岩显微特征及锆石年龄探讨火成岩形成环境及时代。层状火成岩为斑状结构,块状构造,局部发育条带状构造及流动构造。层状火成岩的斑晶主要由火山喷发形成的棱角明显石英、斜长石、钾长石、少量角闪石、黑云母及黄铁矿等晶屑及少量岩屑组成,基质为火山熔浆凝结形成的全晶质矿物,主要由粒度极细的石英、钾长石、绢云母、白云母及少量黑云母等组成,石英和钾长石构成典型的霏细结构。层状火成岩含大量火山碎屑及具流动构造等现象表明其为火山碎屑熔岩类,主要为英安质凝灰熔岩、流纹质凝灰熔岩及角砾熔岩。大宝山矿区中部流纹质凝灰熔岩和东部丘坝一带英安质凝灰熔岩的锆石LA-ICP-MS U-Pb年龄分别为436.4±4.1Ma,MSWD=0.94和434.1±4.4Ma,MSWD=1.9,是加里东期形成的。据大宝山矿区熔岩锆石U-Pb年龄,结合层状熔岩和灰岩及碳质页岩紧密共生及区域深大断裂构造活动特征,我们认为大宝山与层状矿化关系密切的层状火成岩为加里东期海相火山熔岩,粤北一带加里东期海相火山活动可能和形成于加里东期的吴川-四会深大断裂活动有关。     

贵州茂兰喀斯特森林植被演替序列的数量分析

综合运用双向指示种分析法( TWINSPAN)及除趋势对应分析法( DCA)进行分类及排序,确定了贵州茂兰国家级自然保护区森林群落的演替序列。结果表明: 根据DCA排序可将研究区植被群落的演替过程分为四个阶段,即草地→ 灌丛→乔林→顶极群落;根据TW IN SPAN分类结果可将植被分为11个群丛,其中,第Ⅰ 、Ⅱ 、Ⅲ 、Ⅳ 群丛为草本阶段,第Ⅴ 、Ⅵ 群丛为灌丛阶段,Ⅶ 、Ⅷ 、Ⅸ 群丛为乔林阶段,第Ⅹ 、Ⅺ群丛为顶极阶段。茂兰喀斯特植被演替顶极群落为亚热带常绿落叶阔叶林群落,是一种典型的地形— 土壤演替顶极,是植被与当地环境长期适应的结果。      

从埃及之行谈环境物探工作

文章简要介绍作者在埃及之行中所接触到的生态环境问题,主要是:1.沙漠广布;2.阿斯旺水坝引起的生态环境变化;3.大气污染.进而从我国环境地质工作的战略地位出发提出应积极开拓环境物探工作的新领域,并简述已有成效的环境物探工作.     

高密度电阻率法在辽宁分水地区地热开发中的应用

为了开发新能源,我队对辽宁省分水地区使用高密度电阻率法进行地下热水资源的探测,对这种测量系统进行了深入研究。并通过该地区的工程实例总结出该工作方法的技术先进性,在工程地质物探中有着较高的可行性和推广价值。     

甘肃敦煌党河水库TTG地球化学特征、锆石SHRIMP U-Pb定年及其构造意义

甘肃敦煌党河水库岩体以花岗闪长岩为主,并构成英云闪长岩-花岗闪长岩-奥长花岗岩的TTG组合。锆石SHRIMP U-Pb年为440±12Ma (MSWD=2.5),代表TTG系列岩石的侵位时代。岩石化学成分中SiO₂含量约为57.02%~72.75%,随着SiO₂含量的增加,TiO₂、Al₂O₃、MgO、CaO和FeO等的含量相应下降,这表明该套岩石具岩浆成因,是角闪石和斜长石的分离作用控制下岩浆分异的产物。岩石的稀土元素总量较低,轻重稀土分异明显,(La/Yb) _N＝4.70~58.88,无或略具微弱的Eu异常,近于平行的稀土元素配分曲线表明所有岩石具有同成因的亲缘关系。岩石富集大离子亲石元素Rb、K、Th、Sr等,亏损Nb和Ta等高场强元素以及P和Ti。在Rb/30-Hf-3×Ta和Rb/30-Hf-0.25×Nb图解上,所有岩石的投影点落到岛弧到后碰撞区。但从区域地质背景、TTG的产出环境、形成时代及与敦煌地块南北缘火成岩对比分析,认为该TTG系列岩石并非形成于岛孤构造环境,而是加里东造山作用晚期(约440Ma)红柳河缝合带和(或者)阿尔金北缘红柳沟拉配泉俯冲碰撞带,引发富含角闪石的下地壳源岩部分熔融形成岩浆,上侵过程中同化部分陆壳物质形成具有岛弧性质的岩浆岩。     

相山铀矿田成矿物质来源探讨

铀源分析是铀矿床成因研究中的关键问题.在分析区域铀丰度特征的基础上,根据区域成矿物质在地质历史过程中的时空演化,结合相山矿田矿石铅同位素组成及岩、矿石微量元素地球化学对矿田铀源分析的指示,认为下寒武统地层为区域铀源层,相山火山盆地是区域成矿物质的"汇"区,岩浆及期后热液是铀的载体,即岩浆作用实现了铀从"源"到"汇"之间的物质转移.在岩浆演化过程中,铀向气液转移,为铀成矿提供了物质基础,岩浆期后流体-岩石相互作用,也促使了基底片岩、流纹英安岩中的部分铀进入成矿溶液.     

Geochemistry,Paleoenvironment and Mechanism of Organic-Matter Enrichment in the Lower Silurian Longmaxi Formation Shale in the Sichuan Basin,China

To investigate the mechanism of the organic-matter enrichment in the Lower Longmaxi Formation shale, the geochemistry and total organic carbon(TOC) of the Longmaxi Formation black shales in the Jiaoshiba, Zhaotong, and Weiyuan areas of the Sichuan Basin were analyzed. Paleoproductivity proxy parameters(Babio, Siex, and Ni/Al), clastic influx proxies(TiO_2 and Ti/Al), redox indices(V/Cr, Ni/Co, V/(V+Ni), and U/Th), and hydrothermal indicators(Fe, Mn,and Y concentrations; Fe/Ti ratio and a Ni-Zn-Co diagram) were employed to decipher the paleoenvironment of the Lower Longmaxi Formation shales. TiO_2 and Ti/Al indicated low terrigenous detrital influx in all three areas. However, Babio, Siex,and Ni/Al indicated high productivity in the Jiaoshiba area. V/Cr, Ni/Co, and U/Th indicated higher oxygen content with larger fluctuations in the Zhaotong and Weiyuan areas. Fe, Mn, and Y concentrations and the Fe/Ti ratio implied greater active hydrothermal activity in the Weiyuan area. These heterogeneities were considered to be closely related to the paleoenvironment and paleogeography, and the large basement faults that developed during the Chuanzhong paleo-uplift could have provided vents for deep-hydrothermal-fluid upwelling. The redox indices(V/Cr, Ni/Co, and U/Th) and a paleoproductivity proxy(Ni/Al) displayed a significant correlation with the TOC, suggesting that both excellent preservation conditions and high paleoproductivity were the controlling factors for the enrichment of organic matter in the Longmaxi Formation shale. There was no obvious correlation between the clastic influx proxy(Ti/Al) and the TOC due to the extremely low supply of terrigenous debris. The hydrothermal indicator(Fe/Ti) was negatively correlated with the TOC in the Weiyuan area, indicating that hydrothermal activity may have played a negative role in the accumulation of organic matter. This study suggests that the enrichment of organic matter in the Longmaxi Formation marine shale varied according to the paleogeography and sedimentary environment.