[en] This manual is intended to serve as a guide to the chemical procedures involved in Rb-Sr isotopic analysis as conducted at the Institute of Nuclear Sciences. Included are notes on the experimental developments made over the last 2.5 years, especially those involving rock dissolution and cation exchange chromatography

[en] Cosmogenic nuclides, produced in-situ in rocks by the action of cosmic rays on target nuclei, are increasingly being employed by earth scientists in a wide variety of applications. For example, surface exposure dating is used to determine erosion rates, the age of debris flows, alluvial fans, volcanic eruptions, meteoritic impact craters, and glacial deposits, and the timing of recent movement along faults and tectonic uplift. The technique can thus play a vital role in the study of potential hazards from geological processes, by establishing recurrence intervals between them, and establish chronologies and periodicities for major paleoclimatic events. Before surface exposure dating methods using cosmogenic isotopes can be applied even more widely, production rates of the main nuclides of interest must be better known, and their temporal and spatial variabilities determined. This paper summarises the present state of knowledge on production rates of the currently most useful nuclides (¹⁰ Be, ²⁶ Al, ³⁶ Cl, ¹⁴C, ³ He and ²¹ Ne), discusses the main areas of concern, and makes suggestions for future improvement. (author). 83 refs., 7 tabs., 11 figs

[en] The following examples from published papers describe various ¹⁰Be dating and tracing applications undertaken at GNS Science over the past decade. (author). 7 refs., 8 figs

[en] A brief outline is given of the theory and techniques of the potassium-argon, rubidium-strontium and fission-track dating methods and related isotope studies which are currently in use at the Institute of Nuclear Sciences, DSIR. Some limitations of each technique are set out in terms of age range and materials for dating, and the appropriate choice of various mineral and rock types and subsequent age interpretations are discussed. The organisation of project proposals and categories is described and procedures for sample submission and documentation are given

[en] Compilation of abstracts drawn from published and unpublished papers which describe the following topics: ¹⁰Be/⁹Be variations in Pleistocene cyclothems; ¹⁰Be/⁹Be variations in loess; ¹⁰Be/⁹Be dating of Fe-Mn nodules and crusts; ¹⁰Be/⁹Be dating of Antarctic soils; ¹⁰Be and ⁷Be flux rates in rain; ¹⁰Be/⁹Be dating of deep-sea sediments; SED of up-lifted marine terraces. Refs., 8 figs

[en] The following examples from published papers describe various ¹⁰Be dating and tracing applications undertaken at GNS Science over the past decade. (author). 7 refs., 8 figs

[en] Compilation of abstracts drawn from published and unpublished papers which describe the following topics: ¹⁰Be/⁹Be variations in Pleistocene cyclothems; ¹⁰Be/⁹Be variations in loess; ¹⁰Be/⁹Be dating of Fe-Mn nodules and crusts; ¹⁰Be/⁹Be dating of Antarctic soils; ¹⁰Be and ⁷Be flux rates in rain; ¹⁰Be/⁹Be dating of deep-sea sediments; SED of up-lifted marine terraces. Refs., 8 figs

[en] ⁷Be produced in water targets by nuclear interactions of cosmic rays has been measured to determine cosmogenic nuclide production rates as a function of altitude (sea level to 2 km) and geomagnetic latitude (20-79 deg. S). Relative intensities of low energy cosmic ray neutrons have at the same time been measured using neutron monitors based on IGY/NM-64 designed to efficiently thermalise ca. 2-30 MeV neutrons. The research is on-going and we present here preliminary data from the past two years. Water target and neutron flux results are in general agreement, and are consistent with the altitude-dependent scaling factors of Lal [Earth Planet. Sci. Lett. 104 (1991) 4241]. Significant differences between the sea level, latitude-dependent neutron flux data and Lal's predictions are possibly related to the response function of the detector

[en] The Coffs Harbour Block, eastern Australia, includes a sequence of turbidity-current-deposited greywackes and argillites dominated by quartz-poor to quartz-intermediate, volcanic-lithic and feldspathic types. The rocks have a common provenance consisting of dacite with minor andesite and rhyolite, derived from a continental margin volcanic arc. Rb-Sr whole-rock dating of coarse-grained greywackes and argillites suggests that low-grade regional metamorphism (prehnite-pumpellyite to lowest greenschist facies) has completely equilibrated sediments of all grain sizes, giving an age of 318 +- 8 Ma. A subsequent metamorphism which produced thermal biotite on a regional scale over the southern part of the area, re-equilibrated only the fine-grained sediments 238 +- 5 Ma ago; the coarse-grained sediments were unaffected isotopically and still lie on the older isochron. The wide variations in sandstone petrographic modes imply that the older isochron represents neither the age of volcanism in the magmatic arc nor the age of sedimentation at the deposition site, but rather dates the time of earlier metamorphism. (orig.)

[en] Short communication