Kiwi Cairns: Oamaru

I loaded up with a group of third year (final year) students, 2 profs (Chris, and Catherine) and 3 other TA’s (Nick, Hamish, and Sean) for the 6 hour drive to the Oamaru area. We were looking at the Tertiary seds and volcanics in the area. The seds were of course mildly interesting. There were some cool unconformities with Karst formation and subsequent deposition of a unit, followed by another unconformity such that the secondary greensand was only found in the filled Karst of the first limestone. That being said I quickly grew board of poorly consolidated sands, gravels, and limestones. It should be mentioned that NZ geologists use limestone in a very different context than American geologists. They are much more forgiving of other muds incorporated into the limestone. Mostly because they are looking at cold-water limestones, which are not nearly as pure as the warm water limestones, I’m used to seeing in the western US. What the seds lacked the volcanics made up for in spades! The volcanics are the Kakanui mineral breccias. They are a series of subaqueous volcanic eruptions. What makes them awesome is the mineralogy and some of the xenoliths that are brought up from depth. The breccia includes huge amphiboles (cms) and rounded plagioclase, plus some garnets; and then xenoliths of peridotites (lhezolite to be exact), granulites, eclogites, and tertiary seds this is all wrapped up in a silica undersaturated basalt. For those who are not geologists, basically this basalt brought up really deep metamorphic rocks and potentially portions of the lower crust/upper mantle. Needless to say it confused the devil out of myself and everyone else there. Other highlights of the trip involve a prank battle with a giant flipper of kelp (which may have ended up in my bed, though thankfully not my food) and apple picking (I now have heaps and heaps of apples). Bunch of photo’s below.