Petrological modifications in granitic rocks from the Siljan impact structure: evidence from cathodoluminescence.

摘要: Abstract Cathodoluminescence (CL) and microprobe analyses were performed on quartz, plagioclase K-feldspar from granitic rocks in the Siljan impact area, central Sweden. In upper 2200 m vicinity of Gravberg-1 well, secondary reddish luminescing quartz brownish albite (Ab > 98%) (Or 95%) are dominant minerals. Primary magmatic plagioclases (oligoclase-andesine) show blue, yellowish bluish luminescence colours, respectively. The colour is interpreted to have been induced by shock heating episode subsequent elevated temperature granites. pressure effects, as shown shatter cones planar features, retained within granite dominated blue quartz. Most alteration feldspar took place during cooling that followed heating. Post-impact fracturing facilitated infiltration meteoric water, which has further enhanced feldspars.