Geologic discontinuities

Zhou C B, Chen Y F, Jiang Q H, etc. 2008, An interfacial layer model for coupled hydro mechanical analysis in geological discontinuities[J]. Chinese Journal of Rock Mechanics and Engineering, 27[6] 1081-1093. (in Chinese). 

Discontinuities occur in many shapes and sizes and are generally difficult to recognize in advance of mining. They often contribute to fatal accidents, frequently in combination with other factors. Miners, and particularly roof bolt operators and face drillers, need to be trained to recognize geologic discontinuities as soon as they are exposed by mining. They must also be aware of the proper support techniques and have the necessary support materials available. 

Pickett DA, Murrell MT, Williams RW (1994) Determination of femtogram quantities of protactinium in geologic samples by thermal ionization mass spectrometry. Anal Chem 66 1044-1049 Plagnes V, Causse C, Genty D, Pateme M, Blamart D (2002) A discontinuous climatic record from 187 to 74 ka from a speleothem of the Clamouse Cave (south of France). Earth Planet Sci Lett 201 87-103 Polyak VJ, Asmerom Y (2001) Late Holocene climate and cultural changes in the southwestern United States. Science 294 148-151... 

Several models have been proposed (Cast, 1968 Shaw, 1970 Hertoghen and Gijbels, 1976), but the most satisfactory are those based on iterative calculations, because they allow the evaluation of discontinuous events with sudden modifications of melting proportions, which are common in geological open systems (note that such discontinuities, or even the evolution of melting proportions, cannot be accounted for, if the distribution equations are obtained by integration at the limit). The following distribution model (Ottonello and Ranieri, 1977) is a partial modification of Cast s (1968) approach ... 

The first kind of development (being continuous or single-phased) is an evolutionary precondition for the second one (which is two-phased or discontinuous), and this suggested that there might have been a transition from the first to the second developmental strategy in the history of life. Such a transition, incidentally, could well correspond to the Cambrian explosion, i.e. to the appearance of all known animal phyla in a geologically brief period of time. 

Of special interest is the degree of abruptness of the discontinuities. These may be enhanced by clogging of rock pores in the transition zone. In other cases, a geological barrier may be present, coinciding with a suggested phreatic-confined boundary. 

Kohn M. J., Catlos E. J., Ryerson F. J., and Harrison T. M. (2001) Pressure-temperature-time path discontinuity in the Main Central thrust zone, central Nepal. Geology 29, 571-574. 

Geology. The Grindsted Landhll is located on a glacial outwash plain. The upper 10-12 m of the unconhned aquifer consist of an upper Quaternary sandy layer and a lower Tertiary sandy layer, locally separated by discontinuous silt and clay layers (Heron et al, 1998). Investigations of the... 

It has been successfully used in many inversion schemes developed for geophysical data interpretation (see, for example, Constable et al., 1987 Smith and Booker, 1991 Zhdanov, 1993 Zhdanov and Fang, 1996). This stabilizer produces smooth models, which in many practical situations fail to describe properly the real blocky geological structures. It also can result in spurious oscillations when m is discontinuous. 

While this book treats several topics similar to those found in an analytical chemistry text, it endeavors to consider the spatial and temporal scales of the reactions in nature as distinctly different from those of the laboratoiy. For example, in chemical analysis, precipitates (frequently of metastable and active compounds) are formed from strongly oversaturated solutions, whereas in natural water systems, the solid phase is often formed under conditions of slight supersaturation often crystal growth and aging may continue over geological time spans. Interfacial phenomena are particularly important because chemical processes of significance often occur only at phase discontinuities. 

In Labrador, true prehistoric soapstone quarries—as opposed to geological outcrops— where clear evidence of mining or other extractive activities is preserved, have proved to be rather difficult to locate. An exception is the well-documented Fleur de Lys quarry, where Dorset Paleo-Eskimos apparently worked the deposits for many years (3). Quarried zones are found in two discrete localities, referenced as Localities 1 and 2, which are located about 0.5 km apart. The most intensively worked location (Locality 1) consists of a discontinuous series of areas where soapstone was removed, spaced over a distance of 200 m. Preliminary calculations based on the number of preform removal scars and unfinished preforms suggest that material for a minimum of 1000-2000 vessels was mined from this locality alone during the period of time that it was being quarried. 

Kohn MJ, Catlos EJ, Ryerson FJ, Harrison TM (2001) P-T-t path discontinuity in the MCT Zone, Central Nepal. Geology 29 571-574... 

The physical defects have existed widely in the natural rock, such as fracture, joint and fault and other discontinuous structural plane. The physical and mechanical characteristics of the rock have been influenced seriously by the structural plane, and also the seepage and thermodynamic features and other characteristics have been determined mostly according to the structural plane. It involves mine excavation, environment protection, water conservancy construction, radioactive waste disposal and reservoir induced geologic hazard etc. 

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