Cover folding in the Sonmartel Chain (Jura Neuchatelois)     

Dr. Adrian J. Lloyd 《International Journal of Earth Sciences》1964,53(2):551-580

Sonmartel forms part of the anticlinal Cornu-Foulets Chain of the Neuchâtel High Jura. The strata exposed in the district include much of the Malm (Argovien to Purbeckien), the Lower Cretaceous (Berriasien to Hauterivien) and some Tertiary rocks (Siderolithique, Helvetian Miocene). An outline account is given of the Mesozoic formations, the distribution of marker bands being shown on the map (Pl. 1). The structure of the area is discussed in terms of its constituent parts. The folding is concentric but due to erosion-breaching following the earliest movements, subsequent deformation of the Pre- and Post-Kimeridgien rocks differed. The former are gently diapiric, while the folding of the latter is, in part, a gravity effect. Faults normal to the fold axes are present everywhere. They originated as tension cracks but later permitted transcurrent movements. Tear faults are best developed in regions where the trend of the fold axes changes. Thrusts are restricted to the Grand Sonmartel area. The joint systems are thought to result from stresses due to bed-over-bed sliding during the folding. The different types of deformation combine to produce a rhomboidal pattern of dissected cross-folds. Each of these strain-phenomena show that the region has been subjected to stresses of two different orientations, with a third also affecting the vicinity of Grand Sonmartel. These owe their origins to relative movements of basement blocks beneath the area — thrusting during the Post-Stampian phase, the thrusts re-activated as sinistral shears during the Post-Pontian phases when they were joined by conjugate dextral shears. On this basis the Alpine Push theory for the origin of the Folded Jura must be rejected. The Wegmann hypothesis of basement shears accounts best for the structures observed.  相似文献   

Minor elements in perovskite from kimberlites and distribution of the rare earth elements: An electron probe study     

Adrian P. Jones  Peter J. Wyllie 《Earth and Planetary Science Letters》1984,69(1):128-140

We report REE and minor element distributions for perovskites from seven kimberlites (South Africa and U.S.A.). The REE (1.6–6.3 oxides wt.%) are always strongly light REE enriched, often with Ce > La (chondrite-normalized), and show an expected close correlation with whole-rock analyses. Where examined, perovskite contains far more REE than coexisting apatite, by about an order of magnitude. Calculations indicate that iron is mostly present as Fe³⁺ and is low (1.0–2.9 wt.% Fe₂O₃) compared with perovskite from carbonatite complexes such as Oka (4.4 wt.% FeO [3]). In addition to established Nb (0.3–1.7 oxide wt.%), geochemically interesting elements encountered include Zr (up to 1.5 oxide wt.%), Ba and Sr (up to 0.2, 0.4 oxide wt.% respectively). Specific geological applications suggest a possible genetic link between Wesselton pipe and Benfontein Sills kimberlites, and that carbonate-rich dikes in the Premier mine were derived from kimberlites. The overall similarities with incompatible element-rich titanates in veined mantle peridotites suggest a more direct link between kimberlite magmatism and mantle metasomatism.  相似文献   

Impact of Lake Michigan Allocations on the Cambrian-Ordovician Aquifer System     

Adrian P. Visocky 《Ground water》1982,20(6):668-674

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A New Zealand test of the track-etch® method of prospecting for geothermal steam     

N.E. Whitehead  J.E. Gingrich  J.C. Fisher 《Journal of Volcanology and Geothermal Research》1983,15(4):339-354

The Track Etch® system for radon detection was evaluated as a geothermal exploration technique in a known geothermal resource area in New Zealand called the Craters of the Moon (previously known as “Karapiti”). Very strong radon anomalies spaced along mapped fault traces were detected using 60-m sample spacings. Such radon anomalies may indicate good areas to drill for steam. The anomalies detected in these tests were located inside a larger area known to have above-back-ground concentrations of radon and thought to be a generally favourable area for finding shallow steam. Track Etch® radon cups with an improved type of detector were found to be usable in ground temperatures as high as 60°C. There was no direct correlation of radon concentrations with resistivity measurements, but a moderate correlation with near-surface temperature measurements. Varying vegetation cover had no significant effect on the results but there was an apparent correlation with superficial pumice deposits. It is concluded from the tests that the Track Etch method shows promise in vapour-dominated areas for improving drill-hole siting and thus reducing the economic loss of drilling non-productive holes.  相似文献   

Comment on “rejection of palaeomagnetic observations” by P.L. McFadden     

Nicholas I. Fisher  Toby Lewis  Mary E. Willcox 《Earth and Planetary Science Letters》1983,64(2):316-317

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The measurement of watertable levels in structured clay soils by means of open auger holes     

Adrian C. Armstrong 《地球表面变化过程与地形》1983,8(2):183-187

In structured clay soils, water levels in open auger holes (dipwells) respond to water movement through macropores and may mask the existence of drier zones either at depth or within peds. Variability between replicated dipwells expresses the small scale variation in the soil, and statements about soil water regimes should be made in statistical terms. Suitably replicated dipwells give sufficiently precise measurements of mean watertable position for studies of soil water regimes.  相似文献   

The extent and intensity of the urban heat island in Iași city,Romania     

Lucian?Sf?c?Email authorView author&#;s OrcID profile  Pavel?Ichim  Liviu?Apostol  Adrian?Ursu 《Theoretical and Applied Climatology》2018,134(3-4):777-791

The study underlines the characteristics of the urban heat island of Ia?i (Ia?i’s UHI) on the basis of 3 years of air temperature measurements obtained by fixed-point observations. We focus on the identification of UHI development and intensity as it is expressed by the temperature differences between the city centre and the rural surroundings. Annual, seasonal and daily characteristics of Ia?i’s UHI are investigated at the level of the classical weather observation. In brief, an intensity of 0.8 °C of UHI and a spatial extension which corresponds to the densely built area of the city were delineated. The Ia?i UHI is stronger during summer calm nights—when the inner city is warmer with 2.5–3 °C than the surroundings—and is weaker during windy spring days. The specific features of Ia?i’s UHI bear a profound connection to the specificity of the urban structure, the high atmospheric stability in the region and the local topography. Also, the effects of Ia?i’s UHI upon some environmental aspects are presented as study cases. For instance, under the direct influence of UHI, we have observed that in the city centre, the apricot tree blossoms earlier (with up to 4 days) and the depth of the snow cover is significantly lower (with up to 10 cm for a rural snow depth of 30 cm) than in the surrounding areas.  相似文献   

Stable isotope study of the mineralization and alteration in the Madjarovo Pb–Zn district,south-east Bulgaria     

Clive M. Rice  Richard J. McCoyd  Adrian J. Boyce  Peter Marchev 《Mineralium Deposita》2007,42(7):691-713

The Madjarovo ore district is centred on the exposed section of a Lower Oligocene volcano and consists of radially disposed Pb–Zn-precious metal veins and attendant intermediate sulfidation wallrock alteration. Earlier high sulfidation and potassic porphyry style alterations are found in the centre of the district spatially associated with monzonitic intrusions. The total duration of all mineralization and alteration was ca. 300 ka. Stable isotope analyses (S, O, H) have been carried out on a suite of sulfides, sulfates and silicates from the mineralization, high and intermediate sulfidation alterations and a suite of basement rocks. These data range between the following limits: . We also analysed δD of fluid inclusions in quartz and barite for which we obtained, respectively, the ranges of −43.6 to −78.6 and −58.4 to −67.1‰. The data show that high sulfidation alteration was dominated by magmatic fluids with minor meteoric water, whereas the fluids responsible for the intermediate sulfidation alteration were essentially magmatic. The fluids responsible for the intermediate sulfidation Pb–Zn mineralization were mixed magmatic–meteoric and certainly contained a significant meteoric component. Sulphur is likely derived from basement and/or igneous sources. The evolution of alteration and mineralization styles from potassic, porphyry copper style to high sulfidation to intermediate sulfidation can be understood in terms of changing ore fluid composition resulting from an increasing permeability of the system and an increasingly remote source of magmatic fluid with time. These changes link directly to the geological evolution of this volcanic centre.  相似文献   

An Observational Case Study of Persistent Fog and Comparison with an Ensemble Forecast Model     

Jeremy Price  Aurore Porson  Adrian Lock 《Boundary-Layer Meteorology》2015,155(2):301-327

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Spatiotemporal distribution of aridity indices based on temperature and precipitation in the extra-Carpathian regions of Romania   总被引：2，自引：2，他引：0  

Adina-Eliza Croitoru  Adrian Piticar  Alexandru Mircea Imbroane  Doina Cristina Burada 《Theoretical and Applied Climatology》2013,112(3-4):597-607

In the last decades, droughts are a recurrent phenomena in many regions of the world, especially in the subtropics and mid-latitudes, affecting more and more the society. Aridity indices are often used to identify regions prone to that phenomenon. In this paper, we used data recorded in 30 locations in the extra-Carpathian areas of Romania over the period 1961–2007. The De Martonne aridity index (I _DM) and the Pinna combinative index (I _P) were employed in order to identify critical areas in the most important agricultural regions of the country. Monthly, seasonal, annual, and winter wheat and maize growing season datasets of I _DM and annual values of I _P were calculated. The trends were identified using the Mann–Kendall test and Sen’s slope, while ordinary Kriging technique was employed for interpolation. The main findings are that the most vulnerable to semi-aridity are the southeastern regions, especially during the warm period of the year, and that for Romania, the use of I _DM is more appropriate compared to I _P.  相似文献