摘要:

The data given in the literature for the infra‐red identification of carbonate minerals is summarised, and a technique is described which may be used to identify magnesite, smithsonite, dolomite, rhodochrosite, calcite, aragonite, strontianite, cerussite and witherite by means of their infra‐red absorption bands. Two quantitative applications of the use of infra‐red spectroscopy are considered and techniques are outlined for the determination of calcite‐dolomite ratios in carbonate rocks, and calcite‐aragonite ratios in shell

ISSN:0037-0746    

DOI:10.1111/j.1365-3091.1967.tb01903.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY

摘要:

Lithogenesis of the Steinmiihl Limestone of the Arrach Quarry (Jurassic, Austria)The Upper Jurassic Steinmuhl Limestone Group on its type section (Arrach Quarry, Lower Austria) is subdivided into the following four members:These various sedimentary units represent a gradual change in the environments during sedimentation. The sequence sets in with the Filament Limestone. It possibly represents a sublittoral Lamellibranchiata debris and is of Callovian (?)age. Though the marine deposition continued without interruption to the Upper Jurassic, the environment changed markedly. The sea became deeper and the Filament Limestones were followed by pelagic‐bathyal Radiolaria Siliceous Limestones. A distinct difference in the degree of subsidence within the Upper Jurassic geosyncline led to the formation of bathyal furrows and swells. Over the latter the calcilutiteSaccocoma and CalpionellaLimestones with mainly pelagic fossils were deposited in Kimmeridgian and Port‐ landian. Their thickness is small, for currents swept much sediment into the deeper furrows, in which the Oberalm stratas arose in great thickness at this t

ISSN:0037-0746    

DOI:10.1111/j.1365-3091.1967.tb01904.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY

摘要:

A combined petrographical and geochemical study has been made on a per‐ sistent carbonate horizon from the Mansfield Marine Band, an important marker horizon in the Westphalian Coal Measures of the east Pennines. The composition of this carbonate is unusual for it normally consists of ankerite, but in some localities the carbonate is siderite and not ankerite. The position of the carbonate in the sedimentary cycle is discussed and the conclusion drawn that physicochemical conditions were suitable for the precipitation of CaC03 to occur. Furthermore the detrital material in the carbonate band continued to accumulate at a similar rate to the shales above and below the carbonate. The alteration of the CaC03 is thought to have been a diagenetic effect and the result of a change in the physicochemical environment. Variations in the concentration of dissolved sulphur species and their effect on the solubilities of iron and manganese provide an adequate mechanism to explain how CaC03 may alter to siderite on the one hand or ankerite on the othe

ISSN:0037-0746    

DOI:10.1111/j.1365-3091.1967.tb01905.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY

摘要:

Arguments are developed to show that a factor termed preservation potential could bias the operational data of palaeocurrent analysis, and hence any palaeogeo‐ graphical inferences that are drawn. Flow systems and their directional sedimentary response elements are hierarchically organised in the geological present. A flow system can therefore be characterised (within the limitations imposed by preservation potential) only by reference to all the ranks of sedimentary structure generated therein. The operational rock structures generally employed in palaeocurrent analysis are usually low‐ranking and subject to several sources of varia

ISSN:0037-0746    

DOI:10.1111/j.1365-3091.1967.tb01906.x

出版商:Blackwell Publishing Ltd    

年代:1967

数据来源: WILEY