Feldspar cathodoluminescence

Induced Thermoluminescence and Cathodoluminescence Studies of Meteorites Relevance to Structure and Active Sites in Feldspar... 

During this century there has been considerable interest in the application of thermoluminescence studies to the recent history of meteorites. Natural TL provides a means of exploring radiation history and thermal environment in a manner which is complementary to isotopic methods, and the measurement of natural TL is now routine for the numerous meteorites being returned each year from the Antarctic (3,4). However, induced TL measurements have also proved of considerable interest, because the measurements have implications for the earliest history of meteorites. Essentially, the induced TL properties of meteorites are determined, with a few notable exceptions, by the amount and the nature of the feldspar in them, and feldspar is very sensitive to the major processes experienced by meteorites. In the present paper, we describe our recent work on the induced TL properties of meteorites and briefly discuss how these data relate to early meteorite history. We emphasize the relationship between the TL data and mineral properties. We also present here detailed descriptions of the cathodoluminescence properties of primitive meteorites, as these provide new insights into mineralogical controls on TL properties. 

Figure 6. Photomosaics of the cathodoluminescence of four meteorites of types 3.7-5 (a) Hedjaz (type 3.7, top right), (b) Dhajala (type 3.8, center right), (c) Bremervorde (type 4, center left), and (d) Barwell (type 5, bottom). Scale bar, as in Figure 5. These relatively high petrologic type chondrites show a uniform blue feldspar CL, with only an occasional phosphate grain with red CL.

Fig. 7. (A) Blocky zoned meteoric calcite cement (type I) filling mouldic pore microcrystalline type II calcite (white arrow). Note intense bioclast replacement and loose packing (packing proximity = 36%k uncrossed polars. (B) Same field of view observed with cathodoluminescence type I calcite presents sharp CL zonation (black arrow), whereas type II calcite shows CL microzoning (white arrow). Note the high content of K-feldspars and plagioclase. Quartz grains do not show luminescence. AB-1 well 3244.45 m oil zone.

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