Trend Extraction Using Average Interpolating Subdivision     

Jan T. Bj?rke  Stein Nilsen 《Mathematical Geology》2005,37(6):615-634

Spatial averages are robust components of data sets, and therefore well suited as starting points for trend analysis. A natural way of constructing a global trend surface from average values, is to use a subdivision algorithm. This procedure will in some cases reproduce exactly the drift of the data set. Numerical experiments on multibeam echo sounder data show that residual data sets contain no long range correlations. In addition, a variogram analysis clearly identifies the amount of noise in the original data.  相似文献   

浙江桐庐阳新统栖霞组的■类化石及多重地层划分     

YAN Tie-zeng  ZHU Chao-hui  LU Cheng-zhong  and XU Xing-miaoZhejiang Geological Survey  Hangzhou 《地层学杂志》2007,(1)

浙江桐庐栖霞组可划分为二个带:上部为Cancelli naneoschwagerinoides-Verbeekina grabaui带,归属祥播阶;下部为Misellinaclaudiae带,归属罗甸阶。栖霞组被划分出3个正层序和6个四级层序。高频旋回层研究表明:栖霞组主要的成岩环境有台地相、浅海陆棚相和盆地相三种类型,从下至上总体反映为台地向盆地的演化环境。  相似文献   

浙江桐庐阳新统栖霞组的(竹蜓)类化石及多重地层划分     

颜铁增  朱朝晖  卢成忠  许兴苗 《地层学杂志》2007,31(1):79-89

浙江桐庐栖霞组可划分为二个(竹蜓)带:上部为Cancellina neoschwagerinoides-Verbeekina grabaui带,归属祥播阶;下部为Misellina claudiae带,归属罗甸阶.栖霞组被划分出3个正层序和6个四级层序.高频旋回层研究表明:栖霞组主要的成岩环境有台地相、浅海陆棚相和盆地相三种类型,从下至上总体反映为台地向盆地的演化环境.  相似文献   

浙江白垩系上部地层的划分与对比   总被引：13，自引：5，他引：13  

蔡正全  俞云文 《地层学杂志》2001,25(4):259-266

浙江白垩系上部地层可划分为永康群、天台群和衢江群 ,长期以来 ,认为天台群和衢江群不整合覆于永康群之上。通过对代表性盆地岩石地层层序、古生物、同位素年龄资料的综合分析 ,发现三个群的下部地层 (馆头组、中戴组和天台盆地的塘上组 )为下白垩统 ,上部为上白垩统 ;天台盆地塘上组与仙居盆地小平田组为同物异名的早白垩世晚期火山岩层 ,覆于小平田组之上的“塘上组”是两头塘组的下部层位 ;永康生物群和衢江生物群的主要生物化石时代分别为早白垩世晚期和晚白垩世早期 ,但就两个生物群所涵盖的永康群和衢江群生物化石总体而言 ,其时代均应为早白垩世晚期至晚白垩世早期。永康群、天台群和衢江群是早白垩世晚期至晚白垩世时期的同期异相堆积 ,不存在相互叠覆关系。  相似文献   

γ测井反褶积分层解释法若干问题的讨论     

秦积庚  方励  谭庆江 《铀矿地质》1987,(5)

本文简要地叙述了两种α(或ǎ)地质特征参数值现场测定方法的原理,并对比了它们的可靠性。理论分析和一些实验结果表明,γ强度微分分布曲线半对数直线段法可以提供更为可靠的α(或ǎ)参数值,而γ强度分布曲线半对数直线段法受围岩本底值和测量误差的影响较大。文章还讨论了矿层相遇角对地质特征参数值的影响,实验结果和理论计算值是十分符合的。这间接地表明了反褶积分层解释结果几乎不受钻孔条件和地层环境诸参数的影响,这也是反褶积分层解释法的突出优点。最后,从理论上分析了出现“铀含量负值”的原因,并指出选取偏小或偏大的α(或(?))多数值都会导致矿层铀含量分布的失真,特别是在矿层边界附近。据此,现在已提出一种更为有效的而可以普遍采用的,利用微机自动确定α(或ǎ)参数值的方法。  相似文献   

鞍山北东部韧性变形带中BIF型铁矿的转变     

许亚光 《吉林大学学报(地球科学版)》1987,(3)

本文以鞍山地区樱桃园——眼前山一带为例,讨论BIF型铁矿在韧性变形带中的转变,旨在阐明中低温韧性变形带中BIF型铁矿的矿物、化学成份和流体性质的演变;矿石层中组构的变化,特别是该类铁矿特征的条带状构造的演变;韧性变形带中变质与变形的关系及其对铁矿石质量的影响。韧性变形带中铁矿围岩的变化将一起讨论,以便对照说明。  相似文献   

The crustal record in Rajasthan     

K. Gopalan  A. K. Choudhary 《Journal of Earth System Science》1984,93(3):337-342

Age determinations mostly by Rb/Sr whole rock isochrons of the Precambrian rocks of Rajasthan in northwest India are summarized and discussed. On present sampling and subject to its possible bias, the following conclusions can be made. The Untala Granite believed to be intrusive into the gneissic terrain (bgc) east of Udaipur has the oldest age, 2.95 b.y. yet measured for a granite in Rajasthan. This, coupled with the lead isochron age of 3.5 b.y. for detrital zircon from the Aravalli schists by Vinogradov and others extends the basement of Rajasthan well into the Archaean. The time equivalence of thebgc east of Udaipur with the Berach Granite dated only at 2.55 b.y. is not tenable. No satisfactory radiometric age control exists for the onset and duration of the Aravalli Supergroup, believed to be an early Proterozoic linear belt. Heron’s original Delhi Supergroup has recorded acid magmatism widely separate in space and time. The earliest activity between 1700 and 1500 m.y. is recorded mainly in the Alwar basin in northeastern Rajasthan while the younger activity between 850 and 750 m.y. is represented by the ‘Erinpura type’ granites in the central and southern Aravalli sector. This younger event not only has let its thermal overprinting on the older Alwar rocks but also marks the onset of emplacement of the Malani Igneous suite in the trans-Aravalli terrain. This raises the new possibility that the Delhi rocks of Heron represent atleast two chronologically independent sequences with varying geographical extent. The trans-Aravalli terrain is most probably floored by partly reworked, crystalline basement and developed along linear rift zones which acted as loci for high heat flow and igneous activity since about 800 m.y. ago.  相似文献   

内蒙古苏尼特左旗地区二叠纪地层的划分与对比   总被引：5，自引：0，他引：5  

蒋干清  张维杰 《现代地质》1995,9(2):149-161

本文讨论了内蒙古苏尼特左旗地区二叠纪地层单元的划分及其接触关系，认为本区二叠纪地层应包含大石寨组与哲斯组，缺失晚二叠世沉积；描述了代表本区地层序列演化的典型剖面，并对各单位在区域上的延伸及其对比关系进行了简述，认为本区二在纪地层的区域对比应以火山事件沉积为主线，以地层序列演化及生物化石为标志，而不应以岩性相及厚度为主要依据；根据区域地层序列演化分析，认为大石寨组与哲斯组之间的不整合是本区构造事件的代表性界面。  相似文献   

鞍山-本溪地区条带状铁建造的铁同位素与稀土元素特征及其对成矿物质来源的指示   总被引：45，自引：4，他引：41  

李志红  朱祥坤  唐索寒 《岩石矿物学杂志》2008,27(4):285-290

通过Fe同位素、稀土元素与主量元素相结合的方法,对辽宁省鞍山-本溪地区新太古代条带状铁建造(BIF)的成矿物质来源提出了有效制约.BIF的化学成分主要由TFe2O3和SiO2组成,并且具有较低的Al2O3和TiO2含量,表明该地区BIF型贫铁矿是由极少碎屑物质加入的化学沉积岩.稀土元素的总量较低,经页岩标准化后的稀土元素配分模式呈现轻稀土亏损、重稀土富集的特征,具有明显的Eu、Y、La正异常,这些特征表明该地区BIF是古海洋的化学沉积岩,同时具有明显的火山热液贡献特征.用多接收电感耦合等离子体质谱仪(MCICP-MS)测定Fe同位素的结果表明,相对于标准IRMM-014,所测样品均显示Fe的重同位素富集,且Fe同位素组成与Eu异常存在明显的正相关关系,表明该地区BIF中铁的来源与海底火山热液活动密切相关,首次从成矿元素Fe本身为条带状铁建造的成矿物质来源提供了直接的证据.  相似文献   

Oxygen Isotope Study of Paleoproterozoic Banded Iron Formation, Hamersley Basin, Western Australia     

Ken-ichiro Hayashi    Hiroshi Naraoka  Hiroshi Ohmoto 《Resource Geology》2008,58(1):43-51

A submillimeter‐scale variation of δ¹⁸O in quartz was identified in chert and Fe‐oxide mesobands of the Brockman Iron Formation, Western Australia, using an in situ CO₂‐laser fluorination technique. The total range of variation is 11.2–23.0‰, with >5‰ variations within a single mesoband of approximately 2 cm thickness. These data contradict most previous works, which have suggested that banded iron formations are isotopically homogeneous. The present sample was obtained outside of the iron mining area, and as such is considered to have been less altered by the hydrothermal event recently shown to be responsible for the formation of the iron ore. The data suggest that the largest Paleoproterozoic banded iron formations may have formed not in a stable, quiescent sea, but instead as a result of increased influx of iron‐ and silica‐rich solutions during periods of increased magmatism and submarine hydrothermal activity in a rift basin environment.  相似文献