摘要:

SUMMARYTwo pyroclastic sheet‐like deposits were found by the author between the stratigraphic sequence of marine Oligocene sediments of the Vati Group (Rhodes Island, Greece). The lower one is described in this paper.Its uniform thickness over a large area suggests an origin from submarine ash flow. This assumption is also supported by some welding phenomena observed in several thin sections. Submarine eruption of ignimbritic type is advocated to account for these properties. This type of volcanism agrees well with tectonic and paleogeo‐graphic evolution of the Vati Group basin.Strong analogies and relationship between submarine ash flows (gaseous suspension) and turbidity currents (watery suspension) are pointed out. The new term of “igniturbidites” is proposed to characterize some pyroclastic turbidity current deposits genetically related to submarine ash flows.The paleogeographic reconstruction of the Vati Group basin gives some information about the location of the volcanic eruption area and about the submarine travelling of the as

ISSN:0037-0746    

DOI:10.1111/j.1365-3091.1965.tb01562.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY

摘要:

SUMMARYPublished data and new observations from the Tertiary and Ordovician show that non‐multiple, continuously graded beds from turbidite sequences have size decline curves that are either convex, concave, or straight.Utilizing a physical model and knowledge of fluid mechanics of turbulent transport, a formula relating both median and maximum grain‐size to height above the base of the graded bed was obtained. This analysis suggests that the shape of the size decline curve in a continuously graded bed depends on the initial size distribution of particles carried by the turbulent curr

ISSN:0037-0746    

DOI:10.1111/j.1365-3091.1965.tb01563.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY

摘要:

SUMMARYSeveral deformational sedimentary structures are recorded from the non‐marine sandstones of the Lower Coal Measures of Yorkshire. Some of these structures may be termed convolute lamination and for others the term corrugated lamination is proposed. The scope and synonyms of convolute lamination are discussed and both terms are defined and illustrated. The essential difference between convolute lamination and corrugated lamination is the absence of an overall anticline‐syncline morphology in the latter. Rupture of lamination through most of the thickness of the deformed horizons give rise to rupture structures.A petrological investigation of the sediments showed slight variations in both grain size and mineralogy within individually deformed horizons. The structures are considered to be the result of load casting, caused by heterogeneity of the sediment, and/or thixotropic behavi

ISSN:0037-0746    

DOI:10.1111/j.1365-3091.1965.tb01564.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY

摘要:

SUMMARYPresentation of investigations on the hydraulic content of fragments of lamelli‐branches dredged on the continental shelf (diameters between 12 and 0.51 mm).These lamellar fragments have fall velocities greatly different from those of quartz grains with which they are able to coexist in a sediment. The data of G. Rittinger (in TRASK, 1939) and R. W. Budryk (in TRASK, 1939) are not applicable to these fragments.The author points out the interest of a basic documentation for the dynamic study of sedimentatio

ISSN:0037-0746    

DOI:10.1111/j.1365-3091.1965.tb01565.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY

摘要:

SUMMARYTo facilitate simultaneous performances of numerous grain‐size analyses covering the silt and clay fractions, a method has been worked out and the necessary equipment constructed for utilizing a falling drop for determining densities of particle suspensions. A drop is taken out by means of a micro‐syringe at the desired depth in a sedimentation vessel, and ejected into a column of an organic liquid with a slightly lower density. The drop then falls with a constant speed and the time measured with a stopwatch over a certain distance is a measure of the density of the drop, and hence also of the particle concentration in the sedimentation vessel where the drop is taken. In this way it is easily possible to work through twenty samples in a normal working day, including removal of organic matter, dispersion, washing (to remove effects of soluble salts) and evaluating the final resu

ISSN:0037-0746    

DOI:10.1111/j.1365-3091.1965.tb01566.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY

摘要:

Book reviewed in this article:Petrology of the Sedimentary Rocks, 4th ed. F. H. Hatchand R. H. Rostall, revised by J. TrevorGreensmith.

ISSN:0037-0746    

DOI:10.1111/j.1365-3091.1965.tb01567.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY