共查询到10条相似文献，搜索用时 31 毫秒
1.
K. S. W. Campbell Convener 《Australian Journal of Earth Sciences》2013,60(4):423-425
The Mount Black lead‐zinc deposit at Cooleman Plains, southern New South Wales, occurs in the uppermost part of the moderately folded, weakly metamorphosed, Upper Silurian Cooleman Limestone. A joint‐controlled collapse‐breccia zone interpreted as a palaeokarst structure has been partly replaced by quartz, sphalerite, galena, and a little chalcopyrite, pyrite, marcasite, tetrahedrite, arseno‐pyrite, and mackinawite. These minerals show evidence of having encrusted and replaced limestone fragments in the breccia. Oxidic Zn, Pb, Cu, and Fe minerals have formed by the near‐surface oxidation of the sulphides. Petrographic and field evidence indicates that the quartz and sulphides were deposited mainly by encrustation and precipitation from saline solutions (possibly diagenetically expelled connate brines) in cavities, probably at low temperature at shallow depth. The deposit has many similarities to Mississippi Valley‐type lead‐zinc deposits. 相似文献
2.
《Boreas: An International Journal of Quaternary Research》1986,15(1):60-60
Book reviewed in this article:
Mahaney, W. C. (ed.) 1984: Correlation of Quarternary Chronologies 相似文献
Mahaney, W. C. (ed.) 1984: Correlation of Quarternary Chronologies 相似文献
3.
Correlation Analysis for Compositional Data 总被引：1，自引：0，他引：1
Compositional data need a special treatment prior to correlation analysis. In this paper we argue why standard transformations
for compositional data are not suitable for computing correlations, and why the use of raw or log-transformed data is neither
meaningful. As a solution, a procedure based on balances is outlined, leading to sensible correlation measures. The construction
of the balances is demonstrated using a real data example from geochemistry. It is shown that the considered correlation measures
are invariant with respect to the choice of the binary partitions forming the balances. Robust counterparts to the classical,
non-robust correlation measures are introduced and applied. By using appropriate graphical representations, it is shown how
the resulting correlation coefficients can be interpreted. 相似文献
4.
The most generally used method for estimating the basin-wide sequence and scaling of first and last occurrences, based on
their occurrence in local sections, is Shaw’s graphic correlation method. The key step in this method is the determination
of the line of correlation (LOC), which represents the best estimate of the correlation between two local sections, or between
a local section and a composite standard. In general, available techniques for fitting the LOC for multiple sections are tedious,
subjective, or computationally expensive. A new method employing genetic algorithms can dramatically reduce the effort involved
in determining the LOC and produces stable biostratigraphic correlations and composite range charts objectively and efficiently.
Genetic algorithms are an artificial intelligence technique that excels in locating the optimum solution from a large number
of alternative choices. In the case of the LOC, the alternative choices are the number of line segments comprising the complete
line and the positions of each segment’s beginning and end points. For a given number of segments, a wide range of alternative
LOCs can be rapidly evaluated and a potential optimum fit determined. It is also possible to estimate the point when no further
refinement of the fit by adding line segments is necessary. Genetic algorithms can also be applied to other methods for quantitative
biostratigraphy. 相似文献
5.
中国陆相白垩系地层对比 总被引：13，自引：0，他引：13
陆地系统是地球表层系统的重要组成部分,国际上因为缺少系统的陆相白垩纪地质记录,使得中国的陆相白垩纪地层得到了极大的关注.近十余年来,中国陆相白垩系地层学研究发展迅速,但是新的、系统的陆相白垩系地层对比成果一直缺位,这使得不同学者对中国陆相白垩系的认识存在偏差,造成诸多不必要的争论及不便.本文在收集整理前人白垩纪陆相地层对比成果的基础上,补充近十余年来火山岩年代地层学、古生物地层学及磁性地层学资料,对中国陆相白垩纪地层进行了重新对比,旨在为中国陆相白垩系研究提供系统的年代地层框架. 相似文献
6.
With the definition and adoption of the Global Stratotype Section and Point (GSSP) for base of the Visean in China, the newly synthesized zonations and correlation of some significant fossil groups: foraminifera, conodont, coral and brachiopoda near the Tournaisian-Visean boundary beds are reviewed, which help in the recognition of the boundary in various sedimentary facies. The occurrence of two physical events, one pre- and one post- the Tournaisian-Visean boundary is emphasized, which allows for recognition of the position close to the Tournaisian-Visean boundary in the field. The regional correlation in southern China and international correlation throughout Eurasia around the Tournaisian-Visean boundary beds with the GSSP is proposed. 相似文献
7.
8.
尚义煤田的煤岩层对比 总被引：1，自引：0，他引：1
采用岩性段旋回法、标志层法和煤岩层组合特征法等多种方法,对尚义煤田的煤岩层进行综合对比,对指导煤田内地质勘查和煤矿生产具有重要的现实意义。 相似文献
9.
GENERAL CONSIDERATTONS In my previous paper dealing with river profile of equilibrium andknickpoints,I have pointed out that the propagation of knickpoints up-streammay assume two forms:that they may migrate,if rock defended,or they may 相似文献
10.
The most generally used method for estimating the basin-wide sequence and scaling of first and last occurrences, based on their occurrence in local sections, is Shaw’s graphic correlation method. The key step in this method is the determination of the line of correlation (LOC), which represents the best estimate of the correlation between two local sections, or between a local section and a composite standard. In general, available techniques for fitting the LOC for multiple sections are tedious, subjective, or computationally expensive. A new method employing genetic algorithms can dramatically reduce the effort involved in determining the LOC and produces stable biostratigraphic correlations and composite range charts objectively and efficiently. Genetic algorithms are an artificial intelligence technique that excels in locating the optimum solution from a large number of alternative choices. In the case of the LOC, the alternative choices are the number of line segments comprising the complete line and the positions of each segment’s beginning and end points. For a given number of segments, a wide range of alternative LOCs can be rapidly evaluated and a potential optimum fit determined. It is also possible to estimate the point when no further refinement of the fit by adding line segments is necessary. Genetic algorithms can also be applied to other methods for quantitative biostratigraphy. 相似文献