Geology Geology Geology

Sunday, November 16 2014

We are back drilling finally.  Come to find out that only one cone of the tri-cone drilling bit had been working for the past few hundred meters which means the borehole is smaller than what it originally was thought to be.  So the drillers have spent all night reaming out the borehole so that the rest of the drill string with the new collar could actually fit down the hole.  It seems that anything that could possibly go wrong has gone wrong.  The program is now over a month behind which means they are asking people to stay over the holiday.  They will not be drilling but all the equipment will still be on-site so they will need people working security.  I will not remain over the holiday but it makes me feel bad for the people that end up staying here while everyone else goes home to their family.  The one good thing that came out of the last miss-step is a large chunk of rock was caught in the drill bit, so instead of analyzing cuttings from the mud we were able to actually see solid rock from the bottom of the hole.   It is amazing how much information you can get from a rock 2 inches long and 1 in wide rather than looking at cuttings that are less than 1 cm in length.  Tim Little, our local alpine rock expert, looked at the composition of the rock as a whole specimen and then looked at the thin section that was made from the rock and was very surprised at what was seen.  He thinks we are much closer to the zone we plan to core than previously thought.  So the drilling goes on.  We had a large group of people leave this week that had been here since October and we are going to loose another 5 or so people later this week.  This means I will remain in a set position on the 3-11 pm shift doing the curation of samples and labels for the remaining time.  I would rather try to get my hands on different tasks just so I get a better feel of the types of data the team is gathering but I guess there will be a time for that later.  My field work is moving along very well.  I have gathered a few very nice samples of fault gouge that I will be sending to Dr. Reches at OU that I hope to get to run in our Rotary Shear machine next semester and I have also been spending time in the field looking at fluvial deposits along the Whataroa River.  Being near a major fault like the Alpine Fault makes interpreting depositional systems a little different.  In most places you can look at a cross section of a fluvial deposit and work out the depositional environment fairly easy by structures, grain size, grain sorting, and roundness.  But in the fluvial system I am working on, major earthquakes create large landslides along the valleys.  This deposits sediments directly on top of fluvial deposits and it is quite difficult to interpret if there was an earthquake when you see a sequence boundary or if the river had just changed directions and you are looking at a flood plain deposit.  Simon Cox, another Kiwi geologist, will be arriving tomorrow and I hope to spend some time with him in the field to help me sort this problem out.  Either way it is nice to see geology in a different part of the world with different systems at work.