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A. COLOMBO 《Geostandards and Geoanalytical Research》1986,10(2):183-189
This paper discusses the methods most commonly used to evaluate interlaboratory geochemical data for a search of "best" values. It suggests that the Select-Laboratories, Dybczyński, median and mode methods integrated by the visual inspection of the plot of the ordered data can be regarded as general, complementary approaches to data handling. Because of the elusive nature of the problem, a multiple method approach to be accepted and standardized by the geoscientist community is suggested. The importance of ascribing realistic confidence intervals to any derived value is also pointed out. 相似文献
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Fluvial ribbon sandstone bodies are ubiquitous in the Ebro Basin in North‐eastern Spain; their internal organization and the mechanics of deposition are as yet insufficiently known. A quarrying operation in an Oligocene fluvial ribbon sandstone body in the southern Ebro Basin allowed for a three‐dimensional reconstruction of the sedimentary architecture of the deposit. The sandstone is largely a medium‐grained to coarse‐grained, moderately sorted lithic arenite. In cross‐section, the sandstone body is 7 m thick, occupies a 5 m deep incision and wedges out laterally, forming a ‘wing’ that intercalates with horizontal floodplain deposits in the overbank region. Three architectural units were distinguished. The lowest and highest units (Units A and C) mostly consist of medium‐grained to coarse‐grained sandstone with medium‐scale trough cross‐bedding and large‐scale inclined stratasets. Each of Units A and C comprises a fining‐up stratal sequence reflecting deposition during one flood event. The middle unit (Unit B) consists of thinly bedded, fine‐grained sandstone/mudstone couplets and represents a time period when the channel was occupied by low‐discharge flows. The adjoining ‘wing’ consists of fine‐grained sandstone beds, with mudstone interlayers, correlative to strata in Units A and C in the main body of the ribbon sandstone. In plan view, the ribbon sandstone comprises an upstream bend and a downstream straight reach. In the upstream bend, large‐scale inclined stratasets up to 3 m in thickness represent four bank‐attached lateral channel bars, two in each of Units A and C. The lateral bars migrated downflow and did not develop into point bars. In the straight downstream reach, a tabular cross‐set in Unit A represents a mid‐channel transverse bar. In Unit C, a very coarse‐grained, unstratified interval is interpreted as deposited in a riffle zone, and gives way downstream to a large mid‐channel bar. The relatively simple architecture of these bars suggests that they developed as unit bars. Channel margin‐derived slump blocks cover the upper bar. The youngest deposit is fine‐grained sandstone and mudstone that accumulated immediately before avulsion and channel abandonment. Deposition of the studied sandstone body reflects transport‐limited sediment discharges, possibly attaining transient hyperconcentrated conditions. 相似文献
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A. COLOMBO 《Geostandards and Geoanalytical Research》1986,10(1):81-86
This paper extends Nair's exact Table of 952 and 99% confidence intervals for the median to data sets containing up to 300 observations.
It provides for an approximate relationship especially useful when the number of observations is large, and allows to calculate quickly confidence intervals affected only seldom and occasionally by tolerable error. 相似文献
It provides for an approximate relationship especially useful when the number of observations is large, and allows to calculate quickly confidence intervals affected only seldom and occasionally by tolerable error. 相似文献
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A. COLOMBO 《Geostandards and Geoanalytical Research》1980,4(2):199-201
A demonstration is given that the Gamma Transformation Method (GTM) does not achieve its objective insofar as it gives an estimate of the median and not of the mode (unless they coincide) of a given distribution. Nevertheless, because of the inherent high capability of the method to symmetrize a group of data and of its potential validity and use in other statistical fields, a GTM program which can be used on a programmable pocket or portable calculator is presented. 相似文献
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The certification procedure for the preparation of reference materials for ore, ore concentrates and coke samples is presented. Emphasis is put on the problems connected with the evaluation of analytical data, and the approach used to obtain consensus values and associated uncertainties is discussed. In this connection, the application of a certification parameter, to he established prior to the starting of a certification procedure, is suggested. This parameter could be of help in the evaluation of the feasibility of certification. 相似文献
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Ten samples from a Late Messinian section measured at Capo Rossello, a few hundred metres laterally from and stratigraphically immediately below the Miocene/ Pliocene boundary stratotype, have been investigated by various techniques: carbonate content, grain-size analysis, loss on ignition, clay mineral composition, frequency of euryhaline ostracods. Two lithological sub-units. with different palaeoenvironmental implications, are recognized. Both sub-units were deposited after the termination of evaporitic conditions, and immediately after deposition of an ash fall tuff. The lower unit is the Congeria marl which yields the ‘lago-mare’faunal assemblage, the autochthony of which is supported by biometrical analysis of Cyprides agrigentina, indicating brackish, shallow-water conditions with Paratethyan affinities, and the upper, the Arenazzolo, a thin sandy unit indicating a higher energy environment whose duration is estimated at some thousand years. Marine faunas yielded by the Arenazzolo are interpreted as allochthonous. Sedimentary structures suggest a littoral setting at the edge of the lake, or a delta lobe. The main environmental change occurs at the base of the immediately overlying Trubi Formation, where open marine conditions indicative of oceanic depths mark the termination of the Messinian salinity crisis. 相似文献
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A. COLOMBO 《Geostandards and Geoanalytical Research》1980,4(2):239-242
A method which consists essentially in ranking and then plotting on rectangular coordinates the data of a skewed set of results to the purpose of identifying the modal value of the set, is described. The method is simple, fast (if a plotter is used) and requires no calculations. 相似文献
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