Sulfur isotopes of the Nairne Pyrite deposit,South Australia

The Nairne Pyrite deposit occurs in at least five horizons in a succession of graywackes, quartzites, and siltstones of Cambrian age. Pyrite and pyrrhotite have been traced along bedding planes for almost 100 km suggesting, of course, a syngenetic origin for the sulfides. Sulfur isotopic analyses of samples from the Nairne Pyrite open-cut project provide S³⁴ values ranging from –12.8 to –20.6 permil. Such enrichment in S³², even though the spread in S³⁴ values is comparatively narrow, is suggestive of bacteriogenic sulfur which corroborates the geological evidence that the deposit is bacteriogenic — syngenetic in origin.

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Zusammenfassung Die Pyrit-Lagerstätte Nairne umfaßt wenigstens fünf Horizonte cambrischer Grauwacken, Quartzite und feine Sand- bis Tonsteine. Pyrit und Magnetkies sind über eine Distanz von fast 100 km schichtgetreu, was auf einen syngenetischen Ursprung der Sulfide hinweist. Schwefelisotop-Analysen von Pyrit aus dem Tagebau-Projekt erstrecken sich über einen S³⁴-Bereich von –12,8 bis –20,6 Promille. Diese Anreicherung weist auf einen bakteriellen Ursprung des Schwefels hin, obgleich die Spannweite der Resultate sehr eng ist. Somit ist die Feldvermutung einer syngenetisch-bakteriellen Entstehung bekräftigt.

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The isotopic analyses included in this paper were supported through the U. S. Atomic Energy Commission Contract AT (11-1) 1553, for which we are most grateful.     

Analysis of some aromatic hydrocarbons in a benzene-soluble bitumen from Green River shale

The hydrocarbon content of an aromatic fraction, isolated from the bitumen of Green River shale, was studied by mass spectrometry, infra-red spectrometry, gas chromatography and a dehydrogenation technique. The hydrocarbon types and their distribution in this aromatic fraction, as determined by mass spectrometry, include the following: C_nH_2n?6(10%), C_nH_{2n?8 (31 %)}, C_nH_2n?10(18%), C_nH_2n?12(12%), C_nH_2n?14(8%) and a series of alkenylbenzenes (20%). The carbon-number range, empirical formulae and quantity of each compound in the major types are reported. Mass spectra of several compounds and homologous mixtures of compounds isolated from the aromatic fraction are also given.     

Noble gases in eleven H-chondrites

He, Ne, Ar and Xe were measured in aliquots of 11 H-chondrites, to complement trace element studies on the same meteorites (Laulet al., 1972). Bielokrynitschie, Charsonville, Pultusk and Supuhee have lost radiogenic gases before cosmic-ray exposure and Doroninsk, during exposure.     

Aluminum-26 in meteorites—VII. Ureilites,their unique radiation history

Cosmogenic ²⁶A1 activities have been measured by γ-γ coincidence counting in the three ureilites which had not previously been studied. The values in dpm/kg are: Dingo Pup Donga, 38.4 ± 2.4; North Haig, 39.3 ± 4.8; Dyalpur, 55.8 ± 4.8. Five of the six known ureilites thus have lower ²⁶A1 contents, 63 per cent to 77 per cent, than the calculated saturation values, in marked contrast to most other stony meteorites. This cannot be attributed to short cosmic ray exposure ages. Nor do size and depth effects account for the narrow range of ²⁶A1 activities, because a nuclear particle track study indicates that preatmospheric radii were highly variable, from ≥ 40 cm for Goalpara to only a few cm for Dingo Pup Donga. By default, the most likely explanation is that the ureilites had much smaller or much larger orbits than all other stony meteorites.     

Geo-electrical investigations of Manganese ore bodies in India

Summary The Manganese ore-bodies in India are producing certain electrical potential-fields on the surface, which are typical for those deposits and which can exactly be surveyed by combined Potentiometer- and Resistivity-Method. The range of the relative Potentials, recorded so far, are generally varying between 150 to 200 millivolts, near deeper burried deposits accordingly lower but not lower than 100 millivolts, the relative resistivities varying from 50 to 400 megohms. The electrical surface indications are so clear that the respective position of an ore body can be located with an evident exactness as it is proved in this paper. Furthermore it is demonstrated how vaste geological areas can be prospected in a minimum of time by this method for the benefit of the mining industry.

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Zusammenfassung Die Manganerzkörper in Indien erzeugen an der Erdoberfläche elektrische Potentialfelder, die für die Lagerstätten typisch sind und durch kombinierte Potentiometer- und Widerstandsmessungen exakt aufgenommen werden können. Die bisher ermessenen Werte der relativen Potentiale bewegen sich zwischen allgemein 150 bis 200 Millivolt, bei tieferer Lage entsprechend niedriger, jedoch nicht unter 100 m V. Die scheinbaren Widerstände schwanken zwischen 50 und 400 megohm. Die elektrischen Oberflächenindikatoren sind so ausgeprägt, dass das Einschieben der Erzkörper mit beachtlicher Genauigkeit bestimmt werden kann wie in diesem Aufsatz nachgewiesen wird. Des weiteren wird dargetan, wie mittels dieses Verfahrens grosse geologische Räume in kürzester Zeit zum Nutzen des Erz-Bergbaues prospektiert werden können, wofür bislang noch keine geeignete Methode erprobt war.

     

Meteorite stranding surfaces and the Greenland icesheet

Abstract— Thirty years of recoveries in East Antarctica have led to significant understanding of the regional characteristics associated with meteorite stranding surfaces. In Antarctica these sites are characterized by patches of snow‐free blue ice at high altitude on the icesheet in regions where iceflow is highly restricted. Melting is extremely rare or absent and sublimation rates are high, even though meteorite stranding surfaces are predominantly found within regions where accumulation typically dominates. Localized environmental conditions that persist for thousands of years or longer appear to be the dominant factor rather than shorter‐term or seasonal cycles. In this paper we describe our discovery of regions in Northeast Greenland with blue ice areas that exhibit many of the requisite characteristics, suggesting that they are excellent prospects for future meteorite recovery efforts.     

Cenozoic erosion and the preglacial uplift of the Svalbard–Barents Sea region

The creation of the huge fans observed in the western Barents Sea margin can only be explained by assuming extremely high glacial erosion rates in the Barents Sea area. Glacial processes capable of producing such high erosion rates have been proposed, but require the largest part of the preglacial Barents Sea to be subaerial. To investigate the validity of these proposals we have attempted to reconstruct the western preglacial Barents Sea. Our approach was to combine erosion maps based on prepublished data into a single mean valued erosion map covering the whole western Barents Sea and consequently use it together with a simple Airy isostatic model to obtain a first rough estimate of the preglacial topography and bathymetry of the western Barents Sea margin. The mean valued erosion map presented herein is in good volumetric agreement with the sediments deposited in the western Barents Sea margin areas, and as a direct consequence of the averaging procedures employed in its construction we can safely assume that it is the most reliable erosion map based on the available information. By comparing the preglacial sequences with the glacial sequences in the fans we have concluded that 1/2 to 2/3 of the total Cenozoic erosion was glacial in origin and therefore a rough reconstruction of the preglacial relief of the western Barents Sea could be obtained. The results show a subaerial preglacial Barents Sea. Thus, during interglacials and interstadials the area may have been partly glaciated and intensively eroded up to 1 mm/y, while during relatively brief periods of peak glaciation with grounded ice extending to the shelf edge, sediments have been evacuated and deposited at the margins at high rates. The interplay between erosion and uplift represents a typical chicken and egg problem; initial uplift is followed by intensive glacial erosion, compensated by isostatic uplift, which in turn leads to the maintenance of an elevated, and glaciated, terrain. The information we have on the initial tectonic uplift suggests that the most likely mechanism to cause an uplift of the dimensions and magnitude of the one observed in the Barents Sea is a thermal mechanism.     

Polar constituents isolated from Green River oil shale

This paper interprets the mass spectrometric, i.r. absorption and NMR data for 22 compounds obtained from a polar fraction of Green River shale. The major constituents analyzed are believed to be of the following compositional types: C_nH_2nO (cyclohexanols and chain isoprenoid ketones), C_nH_2n?10O (tetralones and indanones), C_nH_2n?7N (tetrahydroquinolines), C_nH_2n?11N (quinolines), C_nH_2n?1NO (alkoxypyrrolines), C_nH_2n?5NO₂ (maleimides), C_nH_2n?8 (tetralins), C_nH_2n?12 (naphthalenes) and C_nH_2n?14 (benzylbenzenes). This work expands the present information about nitrogen, oxygen and aromatic constituents indigenous to Green River shale.     

Some studies of an unusual eucrite: Ibitira

The Ibitira eucrite is remarkable both for its vesicles and its unbrecciated nature. It consists of ~63 vol. % pyroxene (Wo₁₄En₃₈Fs₄₈), 31% plagioclase (An_95–96), ~2% of nickel-iron, troilite, ilmenite, titanian chromite, and 4% of a silica polymorph. It has a mean track density of 1.8 ± 0.3 × 10⁶ cm^?2, mainly due to cosmic rays. Its pre-atmospheric radius must have been at least 10 cm.The absence of complex radiation effects and presence of vesicles place constraints on the thickness of the Ibitira basalt flow. From the freezing time calculations of Provost and Bottinga, it appears that Ibitira came from a flow no less than 2.5 m and probably no more than 10 or 20 m thick. However, this estimate depends strongly on the viscosity of the melt, which is not well known.