kauffy Posted September 2, 2008 Share Posted September 2, 2008 These are very interesting, im hoping someone can explain to me what they are, and or how they were formed. Basically im pretty sure it has something to do with the rocks and how they were formed. The formation is known as the Gerringong Volcanics, and these crystals are in a very hard volcanic grit. Marine fossils are also found in the same sediments. They are very small, but im hoping the pictures are self explainatory! any help in understanding these would be greatly appriciated! Chris "Turn the fear of the unknown into the excitment of possibility!"We dont stop playing because we grow old, we grow old because we stop playing. Link to comment Share on other sites More sharing options...
Guest solius symbiosus Posted September 2, 2008 Share Posted September 2, 2008 They appear to be phenocrysts of plagioclase that were incorporated into the flow(probably at depth). The marine fossils were incorporated as the melt was extruded.??? Link to comment Share on other sites More sharing options...
kauffy Posted September 2, 2008 Author Share Posted September 2, 2008 wow, i think youve got it solius! after doing a little bit of reading on google, that would explain not only the crystals but there placement within the formation, i knew i could count on someone here to help me thanks a lot! "Turn the fear of the unknown into the excitment of possibility!"We dont stop playing because we grow old, we grow old because we stop playing. Link to comment Share on other sites More sharing options...
Uncle Siphuncle Posted September 2, 2008 Share Posted September 2, 2008 Yeah we have a few ancient volcanoes in TX that pushed up through marine sediments, putting echies and such in association with igneous rocks as mentioned. Grüße, Daniel A. Wöhr aus Südtexas "To the motivated go the spoils." Link to comment Share on other sites More sharing options...
Guest solius symbiosus Posted September 2, 2008 Share Posted September 2, 2008 It was a lucky guess. Hard rock geology ain't my thing. The rock appears to be mafic(basalt). As such, it was a surface flow(small xls), so it had pick up the phenocrysts at depth(large xls). Too, some feldspars are pinkish, and associated with mafics, and of course, there is only one way for sea critters to be found in igneous rocks. If you look closely, you might find rinds around the phenocrysts where the magma "cooked them. Link to comment Share on other sites More sharing options...
kauffy Posted September 2, 2008 Author Share Posted September 2, 2008 Well the fossils are in a higher stratagraphic range in the same formation, these crystals i only found on the rock platform and the fossils were in a small band maybe .5-1m above them, although there were different crystals with the fossils every now and again. Above this volcanic grit, 10m or so above the fossils was an iron stained igneous rock, which im sure is also part of the formation "the Gerringong Volcanics" this site actually really interests me so im going to head back down there and search the rest of the coastline, and do some more documentation of the whole area. Dan, im pretty sure the fossils are in assossiation with the igneous rocks, theres no signs of lifting or folding ect... Still interesting tho, got any pictures of this assossiation? that whole uplift, folding ect is pretty amazing when you think about it. Cheers "Turn the fear of the unknown into the excitment of possibility!"We dont stop playing because we grow old, we grow old because we stop playing. Link to comment Share on other sites More sharing options...
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