Low and Very Low Grade Metamorphism (by sarah)
Well.....
I found this lecture interesting but not engaging like Monday's even though it probably got more potential for producing useful stuff. The actual title of the talk was - From mud wrestling to metamorphism.
I think the issue is that I don't really have any interest in met rocks unless they are shock met or contain galuconite. However what the lecture did show me was that I need to go back and look at Big Picture geology ie how compressional and extentional basins fit in with plate tectonics. Since Monday I have been boning up on my mineralogy which with out samples or microscope mainly involves looking at the mineral atlas's.
Being a chicken I have picked up the smallest thinest of the volumes called A Colour Atlas of Rocks and Minerals in Thin Section and am only about a third of the way through it but it does feel like its bump starting my brian - however it is also showing me just how much stuff I have unfortunatly forgotten.
Oh I lie I love Diagenises but that is generally considered mets poor relation by hard rock petrologists (ie those that look at the mineralogy in Ig and met rocks.) The Big D as diagenises is known is a major problem for things like paleo analysis and I think it can muck up the chemical resivours for dating samples but don't quote me on that!
Anyway yesturdays lecture was mainly coming from the stand point of mud which ment I did have a slight interest in it which unfortunatly wasn't really covered because as Steve said some people in the room knew more about it than he did - the interactions of mud and life - I comemeted on the concept that early life may have got its self-replicating molecules such as DNA from the similar property of clays - clays are self replicating mineral and there are a few theories doing the rounds about them acting as catilysts for organic reaction and then being split by tidal processes leading to lots of replication - hmm thats not a good explanation I'll probably do a better one at some point I think I probably explained it on my website The Origins of Complex Hydrocarbons and Early Life though I am starting to cringe at that site that I did as a small part of my undergraduate and may have to update soonish.
Since I did the site I have been to several seminars at the Natural History Museum and went to the EANA confrence in Milton Kenyes just before the pregnancy stuff. So I probably did know more including all the extremophile stuff - though again I haven't read any new litrature on the subject for about three and bit years - this is not becuase there hasn't been any but becuase I haven't been in a position to get at the info.
One of the things I did find interesting and I'm sure I've seen the image before was the concept that even in high grade rocks that have like proper mineral crystals and shouldn't have any pore space or water in them for solid state reactions to occure - there are at the Armstrong level (this is a unit that is like minute) there are tiny spaces and these could harbour fluids and then the even smaller gaps between the grains/crystals could act like conduets. I had suggested capillary action before I realised how small the scale was we were dealing with but I think that what ever the mechanism is it's going to be working in a similar way. Water as a substance has a high surface tensition and so does tend to creep even upwards against gravinty if constrained. I was woundering weather other fluid would have higher surface tensions and what sort of temperatures and pressures they would be able to survive.
I assume acids tend to be solutions in water but is the presance of H20 actually nessacery for an acid to exist and what what sort of conditions are needed to maintain them? Remember we are dealing with met rocks here - this means they will have been heated, they will have been squashed and probably multiple times.
And here I detect the danger to my success in this course - I am actually interested in everything and I am having to fight myself not to become side tracked - again on Weds I sat in Carina's office - I was going to do some reading but instead found I was far to interested in the talk she was having with one of her colleges on disastor and risk management - we're talking volcanoes and Tsunarmis here - I was supposed to be reading but ended up listening avidly and then even offering my opinion which I probably shouldn't have done.
It is vitally important that I do not become side tract as I have my first essay due on the 3rd of Nov and it can not be late - at all (unless I get a drs note they hastily added whilst looking at me - I can't think why). Word limit is 3000 words which I feel is going to be hard to stay within. I still have no libary access but found I had some papers on the topics I want to write about anyway which is cool. To say I am panicking is probably an under statement but I am also enjoying this - my brain is being stretched and I like it 🙂
Sorry about the incoherent bable!
Thu 2nd Oct 2008 9:05 am 
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