BRUCS: a new system for classifying and naming mappable rock units

A new scheme is introduced for classifying and naming mappable rock bodies that lack primary stratification. In recognition of their distinctive geological characteristics, these ‘nonstratiform’ bodies are defined and classified according to their 3D form, spatial distribution and genetic relationships, in two hierarchical (parent-child) chains: one for intrusions and one for tectonometamorphic units. Geologically complex units, encompassing bodies of different genetic classes, are classified in a third chain reserved specifically for ‘mixed-class’ units. The new classification scheme is offered as an alternative to existing recommendations in the International Stratigraphic Guide and North American Stratigraphic Code, in which nonstratiform bodies are recognised and defined primarily by their lithological character. BRUCS (the BGS Rock Unit Classification System) combines the three new parent-child chains for nonstratiform units with the well-established chain for stratiform units (bed-member-formation-group-supergroup) to create a flexible, practical and effective solution for classifying and naming all mappable rock bodies. The taxonomic rigour of BRUCS means the considerable capabilities of modern digital systems for managing and communicating mapping data can be exploited fully.

The Lower Kimmeridgian of the Wieluń Upland and adjoining regions: lithostratigraphy, ammonite stratigraphy (upper Planula/Platynota to Divisum zones), palaeogeography and climate-controlled cycles

The Early Kimmeridgian of the Wieluń Upland and adjoining regions, after the decline of sedimentation of the deep-neritic sponge megafacies (Częstochowa Sponge Limestone Fm.) and associated limestones and marls with poor benthic fauna (Pilica Fm.) during the Planula Chron, showed the subsequent development of moderately shallow-water biostromal chalky limestones with siliceous sponges and corals, replaced laterally by micritic limestones and marls (Prusicko Fm.) during the Platynota Chron and the earliest Hypselocyclum Chron. Towards the north and south shallow-marine carbonate platforms occurred (represented by deposits of the “oolitic” fm.), whereas towards the north-west and west deeper marine facies, represented initially by limestones with siliceous sponges (Częstochowa Sponge Limestone Fm.), and later during the Hypselocyclum Chron by bedded limestones and marls with ammonites (Burzenin Fm.) were deposited. This palaeogeographic pattern was controlled by the synsedimentary tectonics. The detailed biostratigraphical classification of the deposits studied from the Platynota to the Divisum zones, and their lithological character, enable the recognition of the primary sedimentary cyclicity by comparison with the well dated short eccentricity cycles in the coeval succession of south-eastern France. The two appendixes enclosed give the characteristics of: (1) the characteristics of the ammonite faunas especially of the families Ataxioceratidae and Aulacostephanidae (where two new species are established – Balticeras samsonowiczi sp. nov., and Rasenioides glazeki sp. nov.); (2) the newly established lithostratigraphical units: the Prusicko Fm., and the Burzenin Fm., and the smaller rank units (members, beds) recognized therein.

Research on Gas Content Prediction Model of Hebi No.6 Mine Based on Quantification Theory

The mathematic principles and numerical arithmetic of quantification theory Iare studied of gas content prediction model and actually measured data during geological prospecting and producing of Jincheng Hebi No.6 coal seam are collected. Thus, twenty-nine reliable data of gas content are gained. Then, the gas content prediction model is founded based on quantification theory by selecting bedrock thicknesscoal seam thickness as quantitative values and lithological character of coal roof as qualitative value. By results of calculation and estimation, the model precision can meet the desire of engineering precision, showing that using quantification theory to predict gas content is feasible.

W. H. Fitton's Geology of Australia's Coasts, 1826

In an appendix to Phillip Parker King's 1826 book Narrative of a Survey of the ... Coasts of Australia..., W. H. Fitton attempted, largely on the basis of the rock specimens collected on King's and earlier expeditions, to summarize the geological (mainly lithological) character of Australia's coastal regions. We have examined and identified the specimens, preserved in the Natural History Museum, London, in terms of modern concepts, indicating their stratigraphic affinities. Fitton realized the limitations of his work and, wishing to encourage better knowledge, appended 'Instructions for collecting geological specimens', stressing the need to understand not only the materials, but the order of formation. Fitton was indicating that a sense of stratigraphy was essential to the progress of geology. Despite its deficiencies, Fitton's paper was an important step towards understanding the geology of an almost unknown continent.

A laboratory investigation of some factors affecting the stability of a mine in the Eastern Transvaal coalfield, South Africa

The stability of roofs and floors in pillared coal mines is affected by a number of properties of the strata above and below the coal seam which is worked. These include the lithological character of the rocks, the sedimentary features contained within them, the geomechanical properties of the rocks, notably their strength and deformation moduli, the durability of the rocks on exposure, and the incidence and geometry of discontinuities. Instability also can be associated with the development of excessive methane and water pressures in the strata surrounding a worked coal seam. Accordingly, rock-core material was obtained from a mine in the Eastern Transvaal Coalfield in order to investigate the influence of certain of these properties on the stability of the roof and floor of the mine. The investigation showed the existence of a number of sedimentary facies that had different geological characteristics and geomechanical properties. A large number of compressive and tensile strength tests were carried out on the rock-core material, as was permeability testing. The latter was undertaken using an Ohle cell, a Bernaix cell and a Hoek triaxial cell. The permeating fluids were nitrogen, methane and water, except in the case of the Hoek cell in which only methane was used. The Hoek cell allowed permeability to be determined under different stress conditions. In addition, the geodurability of the rocks of the argillaceous facies also was determined. The compressive and tensile strength of the various facies varied notably and the latter frequently showed significant anisotropy. Permeability tended to increase with increasing grain size in the coarser-grained facies whereas the opposite tended to occur in the fine-grained facies when tested with gas. The application of stress brought about a decrease in permeability. In the Bernaix cell, divergent flow was greater than convergent flow. The tensile stress that developed during divergent flow testing with water caused some specimens to fail. The durability indicated that some of the argillaceous material was of very poor quality.

Giant granulite terranes of northeastern Superior Province: the Ashuanipi complex and Minto block

The Ashuanipi complex and Minto block of the Superior Province are large regions that have been classified as "high-grade gneiss" terranes on the basis of the presence of orthopyroxene-bearing units. Like the granite–greenstone and metasedimentary subprovinces of the southern Superior Province, the two terranes consist predominantly of intrusive rocks, but are distinguished by their primary magmatic orthopyroxene. Both "high-grade" and "gneiss" are misnomers because granulite-facies gneisses are only sparingly present and the regions consist dominantly of massive, unmetamorphosed plutonic rock.The Ashuanipi complex consists of a deformed, metamorphosed package of metasedimentary rocks and primitive, early tonalite cut by widespread orthopyroxene ± garnet granodiorite (diatexite), as well as plutons of tonalite, granite, and syenite. Based on its lithological and chronological similarity and on-strike position, the complex appears to be the continuation of metasedimentary subprovinces such as the Quetico. Its evolution involved deposition of immature greywacke in an accretionary prism, early arc (tonalitic) magmatism and deformation, followed by widespread intracrustal magmatism in the period 2700–2670 Ma. Both metamorphic and igneous rocks record equilibration under granulite-facies conditions (700–835 °C; 0.35–0.65 GPa; [Formula: see text] ~0.3) and indicate exposure levels of ~20 km.The Minto block at the latitude of Leaf River consists of several north-northwest-trending domains of similar scale and diversity to the east-trending subprovinces of the southern Superior Province. The central Goudalie domain is dominantly amphibolite-facies tonalitic rocks including some with ages >3 Ga, with small belts of volcanic and sedimentary origin. Lake Minto domain contains poorly preserved supracrustal remnants in a plutonic complex comprising hornblende granodiorite, clinopyroxene ± orthopyroxene granodiorite, orthopyroxene–biotite diatexite, and granite. The hornblende granodiorite suite constitutes most of the Utsalik and Tikkerutuk domains and is thought to represent continental arc magmatism. On the basis of their distinct aeromagnetic and lithological character, two additional domains are evident north of the Leaf River area, the Inukjuak domain in the west and the Douglas Harbour domain in the east.The northerly grain of the Minto block appears to have been established in situ with respect to the easterly belts of the southern Superior Province (i.e., no large-scale block rotation) during the same interval of time (3.0–2.7 Ga). Modification of the tectonic framework for the Superior Province is required to explain Minto arc magmatism. In the interval ~2730–2690 Ma ago, a continental magmatic arc built the Berens River and Bienville subprovinces and Minto block on the southern and eastern edges, respectively, of a northern protocratonic foundation. In the same period, primitive volcanic arcs and accretionary prisms developed outboard on oceanic crust and were accreted to form a southern tectonic regime.

Diagenetic influences on reservoir properties of the Sherwood Sandstone (Triassic) in the Marchwood geothermal borehole, Southampton, UK

Petrological studies of the Sherwood Sandstone of the Marchwood Borehole show that the formation is made up of two units of differing primary lithological character: a lower unit with lithic sandstone and conglomerate, and an upper unit with arkosic sandstone. A combination of compaction and calcite cementation (early and late) has severely reduced porosity and permeability in the lower unit. In the upper unit compaction is again important, but several beds have largely escaped cementation, and their primary porosity has been enhanced by leaching of feldspars. The secondary porosity reaches 7% in some samples. Oxygen and carbon isotope data for the early (calcrete) cements indicate isotopic equilibrium with typical freshwater compositions. The later cements yield more variable values, indicating precipitation under a wider range of conditions.

XII.—On Salpingostoma dasu: A New Carboniferous Seed from East Lothian

In a recent paper (Gordon, 1938) reasons were given for the belief that semi-arid conditions prevailed during Lower Carboniferous times in the neighbourhood of North Berwick, East Lothian. The evidence was opposed, in a measure, to that advanced by Mr George Barrow in the East Lothian Memoir (1910) to substantiate the same position. He had relied on the absence of fossils as part proof; but, in point of fact, fossil plants have been obtained in abundance from the actual bedded ashes of Oxroad Bay that he considered (a) to be unfossiliferous, and (b) to have been formed in a manner similar to beds on the Springbok Flats of the Transvaal. The plants that have now been obtained showed xerophytic features, and, consequently, a semi-arid climate was proved on positive evidence. Other positive evidence of a lithological character was also presented in confirmation (Gordon, 1938, pp. 352, 353).

XII.—On Salpingostoma dasu: A New Carboniferous Seed from East Lothian

In a recent paper (Gordon, 1938) reasons were given for the belief that semi-arid conditions prevailed during Lower Carboniferous times in the neighbourhood of North Berwick, East Lothian. The evidence was opposed, in a measure, to that advanced by Mr George Barrow in the East Lothian Memoir (1910) to substantiate the same position. He had relied on the absence of fossils as part proof; but, in point of fact, fossil plants have been obtained in abundance from the actual bedded ashes of Oxroad Bay that he considered (a) to be unfossiliferous, and (b) to have been formed in a manner similar to beds on the Springbok Flats of the Transvaal. The plants that have now been obtained showed xerophytic features, and, consequently, a semi-arid climate was proved on positive evidence. Other positive evidence of a lithological character was also presented in confirmation (Gordon, 1938, pp. 352, 353).

IX.—Sedgwick Museum Notes. On the Age of the Creechbarrow Limestone

On the north side of the outcrop of the Chalk in the Isle o Purbeck, there is an outlier of Tertiary beds the exact age of which has given rise to some discussion. There must be some reason for the form of Creechbarrow Hill, and the outline suggests that it is due to some hard bed near the top, which we find on close examination to be a tough limestone, a considerable portion of which is hard and porcellaneous. The upper beds of this conical hill, which rises to a height of 637 feet above sea-level, are cut off from the adjoining masses, and therefore no continuous section can be traced to the well-known formations on the south or on the north. The section is further complicated by the occurrence of faults on both the north and south sides. We have, therefore, only the lithological character and fossil contents to depend upon for the correlation of the beds occurring in this outlier.