编辑等高线图的机助几何设计法     

Walt.  DJ 吴志忠 《地图》1993,(3):36-41

导言来自地形测量,地质测量及其它测量或其它实验观测的三维数据常常是以等高线图表示的。展示等高线图并不能提供直接可见的三维图象。但在实践中等高线图却很有用,如设计公路时研究道路位置,机场定址,环境评估等。从等高线图中获取的数据对建立三维数字地形模型也很有用。从等高线图用手工获取或提取数据是很麻烦的。因而存储等高线图以便计算机进行处理的  相似文献   

藏南米拉山地区中新世埃达克质岩石的年代学、地球化学和成因     

孙浩哲  赵志丹  朱弟成  刘栋  王青  唐演  齐宁远  董国臣 《岩石学报》2021,37(11):3479-3500

中新世是青藏高原隆升、增厚的重要时期,并且在这一时期内拉萨地块广泛发育碰撞后岩浆岩。本文对南拉萨地块米拉山地区的钙碱性钾质火山岩进行了锆石U-Pb年代学、Lu-Hf同位素和全岩主量、微量元素的测定与系统研究。米拉山中新世火山岩为粗面英安岩、英安岩和流纹岩（SiO₂=59.89%~71.78%）。锆石U-Pb定年结果为16.1±0.2Ma~20.4±0.3Ma,表明其喷发时代为中新世。岩石具有较高的Al₂O₃含量（13.54%~16.31%）,低MgO（0.46%~1.95%）、高Sr（388×10^-6~804×10^-6）、低Y（6.55×10^-6~11.20×10^-6）和Yb（0.70×10^-6~1.07×10^-6）的特征,具有较高的Sr/Y值（51~80）、低相容元素（Cr=4.26×10^-6~32.53×10^-6,Ni=4.16×10^-6~25.75×10^-6）和弱Eu负异常。岩石具有轻稀土元素和Rb、Th、U、K等元素富集、重稀土元素和高场强元素Nb、Ta、Ti亏损的特征。米拉山中新世火山岩显示出埃达克质岩石的地球化学特征,可能来自于的镁铁质加厚下地壳的部分熔融,推测下地壳源区是石榴石角闪岩。锆石ε_Hf（t）值为+2.2~+7.8,表明源区为新生地壳物质,有俯冲板片熔体加入。米拉山中新世火山岩的喷发时代与米拉山断裂活动时间一致,二者可能同为拉萨地块岩石圈拆沉的结果。  相似文献   

内蒙古清水河木纹石特征及其形成机制          下载免费PDF全文

汤家辉  董国臣 《中国地质》2021,48(3):872-882

内蒙古呼和浩特南部的"木纹石"为碳酸盐岩,其质地细腻致密,具有木纹般纹饰,由红色环带及黄色环带构成。本文在野外调研的基础上,针对岩石及其红色和黄色环带进行了矿物学、岩石地球化学分析,并利用扫描电镜对元素的分布进行测试。研究表明,木纹石由中—细晶白云石组成,胶结物以泥质绢云母、钾长石和黏土矿物为主,含少量稀土矿物、钛铁矿、黄铁矿和褐铁矿等金属矿物。岩石化学和地球化学分析发现,红色环带较黄色环带富Al_2O_3、K_2O、Fe_2O_3、Sr,特别是Fe元素,以线扫描中Fe的计数频率(cps)350作为标准可以很好的区分红黄条带。据Yb/(Ca+Mg)-Yb/La图解分析显示出岩石受热水活动迹象,表明海相碳酸盐岩在成岩后期演化过程中,地下(热)水沿裂隙进行渗透淋滤,由于温度差异,Fe氧化程度差异,致色因素三价Fe含量不同,使得岩石具有红-黄相间条纹特征,形成以裂隙为边界状如树木纹饰的环形环带。  相似文献   

大陆碰撞过程的火山岩响应：以西藏林周林子宗火山岩为例   总被引：1，自引：0，他引：1       下载免费PDF全文

董国臣  莫宣学  赵志丹  朱弟成 《沉积与特提斯地质》2021,41(2):332-339

印度-亚洲大陆碰撞伴生有大量火山活动,其中,林子宗火山岩发育最广,遍布碰撞带北侧的冈底斯带,形成长逾1200 km的火山岩带。林周地区作为林子宗火山岩的命名地,该套火山岩发育相对齐全,为安山岩、流纹岩及相应的火山碎屑岩夹沉积碎屑岩组合,顶部发育巨厚流纹质凝灰岩,可以划分出三个火山旋回,其生成时代介于63.89~48.73 Ma。岩石学和地球化学资料显示,林子宗火山岩自下而上SiO₂和K₂O含量以及Al₂O₃饱和度增加,其岩浆从早到晚由中性、中钾和准铝质变化到酸性、高钾和过铝质,晚期喷发巨厚的火山灰流,反映区域地壳明显的加厚,由早期的30~40 km变化到晚期的50~60 km。火山岩相对富集Cs、Rb、K、U,亏损Ta、Nb、Ti、Sr、Ba、P,早期与桑日组安山岩地球化学特征相近,而中—晚期与乌郁、扎嘎等地渐新世高钾火山岩相似,表明早期岩浆具有新特提斯洋俯冲板片印迹,而中—晚期具有后碰撞作用特点。林子宗火山岩作为印度-亚洲大陆碰撞过程的响应,记录着古新世至始新世（64~48 Ma）印度-亚洲大陆之间的碰撞向碰撞后演化过程。  相似文献   

云南中甸地苏嘎印支期斑岩地球化学特征及其成矿标识     

潘彦宁  董国臣  李雪峰  王鹏  孙转荣  董朋生  李华伟 《现代地质》2019,33(6):1275-1285

地苏嘎印支期斑岩体位于中甸岛弧东斑岩带的北端,岩性为石英闪长玢岩,与普朗超大型斑岩铜矿的成矿岩体同属于甘孜—理塘洋壳俯冲作用晚期岩浆活动的产物。全岩地球化学特征显示,地苏嘎石英闪长玢岩具有中等的SiO₂含量,较高的Al₂O₃及全碱(K₂O+Na₂O)含量。全岩亏损高场强元素,富集大离子亲石元素,稀土元素配分曲线呈典型的右倾状,显示出轻稀土富集、重稀土相对亏损的特点。主量元素和微量元素成矿指示方面的研究结果表明:与普朗38个与成矿有关的石英闪长玢岩的全岩数据相比,地苏嘎石英闪长玢岩具有相对较低的SiO₂和Y含量、较高的∑REE和(La/Yb)_N比值,但二者的Al₂O₃/(CaO+Na₂O+K₂O)比值及MnO含量差别不大。在成矿与非成矿斑岩的SiO₂- Al₂O₃/(CaO+Na₂O+K₂O)和Y-MnO图解中,地苏嘎石英闪长玢岩与普朗石英闪长玢岩数据投图结果类似。此外,地苏嘎斑岩体在物探异常、化探异常及遥感影像特征上具有明显的矿化标志,同时岩体的剥蚀深度小于侵位深度,有利于矿床的保存。以上研究结果表明地苏嘎斑岩体具有成为斑岩型铜矿床的潜力。  相似文献   

云南个旧似长石正长岩类及其岩石成因     

王宇菲  董国臣  陈薇  苏麟  殷国栋  朱红运  李华伟 《地学前缘》2019,26(4):209-220

云南个旧碱性岩体主要的岩石类型有碱性正长岩和似长石正长岩,其中,似长石正长岩中出现大量似长石矿物霞石、方钠石和碱性暗色矿物。本文根据矿物成分及特征,将这些似长石正长岩进一步划分为黑榴霞石方钠正长岩、霞石方钠正长岩、霞石正长岩及方钠霞石正长岩4类。岩石地球化学结果表明,4类岩石的地球化学行为整体表现出过碱质岩的特征,K2O+Na2O含量很高,为钾玄岩系列,同时表现出钾质的特点。分异指数高,呈现高度分异演化特点。稀土元素变化大,轻重稀土元素分异明显,富集轻稀土元素,亏损重稀土元素。微量元素富集大离子亲石元素Th、U及Zr、Hf等高场强元素,亏损Ba、Sr大离子亲石元素,而P和高场强元素Ta、Ti亏损,同时Cr、Co、Ni含量非常低,具有中等的负Eu异常和微弱的负Ce异常。研究表明,似长石正长岩在岩浆演化过程中表现出明显的分离结晶作用特征,且岩浆起源温度较高,约为835℃,起源较深。个旧似长石正长岩为A型岩套A1亚型,结合构造判别图解,认为其可能来自角闪石或者金云母相矿物存在的富集地幔,形成于燕山晚期伸展的构造背景,岩浆在较高温度下高度结晶分异,并在侵位过程中伴随陆壳成分的混染。  相似文献   

NAPL source zone depletion model and its application to railroad-tank-car spills     

Marruffo A  Yoon H  Schaeffer DJ  Barkan CP  Saat MR  Werth CJ 《Ground water》2012,50(4):627-632

We developed a new semi-analytical source zone depletion model (SZDM) for multicomponent light nonaqueous phase liquids (LNAPLs) and incorporated this into an existing screening model for estimating cleanup times for chemical spills from railroad tank cars that previously considered only single-component LNAPLs. Results from the SZDM compare favorably to those from a three-dimensional numerical model, and from another semi-analytical model that does not consider source zone depletion. The model was used to evaluate groundwater contamination and cleanup times for four complex mixtures of concern in the railroad industry. Among the petroleum hydrocarbon mixtures considered, the cleanup time of diesel fuel was much longer than E95, gasoline, and crude oil. This is mainly due to the high fraction of low solubility components in diesel fuel. The results demonstrate that the updated screening model with the newly developed SZDM is computationally efficient, and provides valuable comparisons of cleanup times that can be used in assessing the health and financial risk associated with chemical mixture spills from railroad-tank-car accidents.  相似文献   

Biochemical indicators for the bioavailability of organic carbon in ground water   总被引：1，自引：0，他引：1  

Chapelle FH  Bradley PM  Goode DJ  Tiedeman C  Lacombe PJ  Kaiser K  Benner R 《Ground water》2009,47(1):108-121

The bioavailability of total organic carbon (TOC) was examined in ground water from two hydrologically distinct aquifers using biochemical indicators widely employed in chemical oceanography. Concentrations of total hydrolyzable neutral sugars (THNS), total hydrolyzable amino acids (THAA), and carbon-normalized percentages of TOC present as THNS and THAA (referred to as "yields") were assessed as indicators of bioavailability. A shallow coastal plain aquifer in Kings Bay, Georgia, was characterized by relatively high concentrations (425 to 1492 μM; 5.1 to 17.9 mg/L) of TOC but relatively low THNS and THAA yields (∼0.2%–1.0%). These low yields are consistent with the highly biodegraded nature of TOC mobilized from relatively ancient (Pleistocene) sediments overlying the aquifer. In contrast, a shallow fractured rock aquifer in West Trenton, New Jersey, exhibited lower TOC concentrations (47 to 325 μM; 0.6 to 3.9 mg/L) but higher THNS and THAA yields (∼1% to 4%). These higher yields were consistent with the younger, and thus more bioavailable, TOC being mobilized from modern soils overlying the aquifer. Consistent with these apparent differences in TOC bioavailability, no significant correlation between TOC and dissolved inorganic carbon (DIC), a product of organic carbon mineralization, was observed at Kings Bay, whereas a strong correlation was observed at West Trenton. In contrast to TOC, THNS and THAA concentrations were observed to correlate with DIC at the Kings Bay site. These observations suggest that biochemical indicators such as THNS and THAA may provide information concerning the bioavailability of organic carbon present in ground water that is not available from TOC measurements alone.  相似文献   

西藏班公湖地区侏罗纪-白垩纪沉积及古海洋盆地的演化          下载免费PDF全文

谢国刚莫宣学  赵志丹董国臣 《地学前缘》2009,16(4):31-39

在西藏1∶25万喀纳幅、日土县幅地质调查图成果的基础上,重建了班公湖-怒江结合带西段3个地层区的侏罗纪-早白垩世沉积地层序列,对地层纵向、横向序列变化和沉积环境进行对比分析,指出在侏罗纪-早白垩世时,班公湖-怒江中特提斯洋盆沉积与其南、北两侧大陆边缘沉积有明显差异;中特提斯海洋盆地演化经历了早-中侏罗世深海-半深海沉积、晚侏罗世-早白垩世残余海(洋)盆地沉积和晚白垩世残余海盆消亡等3个阶段。  相似文献   

A multivariate assessment of the coral ecosystem health of two embayments on the lee of the island of Hawai'i     

Parsons ML  Walsh WJ  Settlemier CJ  White DJ  Ballauer JM  Ayotte PM  Osada KM  Carman B 《Marine pollution bulletin》2008,56(6):1138-1149

Four coral-dominated coastal sites within two embayments (Kealakekua Bay and Honokōhau Bay) on the lee of the island of Hawai'i were studied to assess evidence of anthropogenic impacts in these relatively pristine locales. Nutrient-loading parameters were analyzed in relation to benthic composition data. Statistically, there were significant positive relationships between nitrate+nitrite, silicate, and ammonium with the abundance of macroalgae, coralline algae, and dead coral, and between delta(15)N and dead coral abundance. The north outside site of Kealakekua Bay and the south outside site of Honokōhau Bay appear to be most impacted by nutrient-loading factors in each bay, respectively. Comparisons with past nutrient data indicate that nutrient inputs have increased to the two bays, and that early impacts of these increased loadings are evident. It is predicted that at current nutrient-loading rates, the north sites of Kealakekua Bay and the south sites of Honokōhau Bay will exhibit evidence of further degradation in future years.  相似文献