Geo junkets: New Zealand, North Island (Part 1)

Jesse Garnet White (USA) Fig. 1. Legend/Key:1 = Sediments (Cretaceous and Cenozoic).2 = Greywacke (Permian and Triassic).3 = Schist (Carboniferous to Cretaceous).4 = Volcanic rocks (Cretaceous and Cenozoic).5 = Sediments and ophiolites (Northland and East Coast allochthon) (Cretaceous and Oligocene).6 = Pyroclastic rocks (Triassic and Jurassic).7 = Limestone, clastics and volcanic rocks (Central and Eastern sedimentary zone) (Cambrian to Devonian).8 = Granitoids (Paleozoic and Cretaceous).9 = West Fiordland metamorphic zone (Paleozoic and Cretaceous).10 = Ophiolites and pyroclastics (Permian).11 = Volcanic rocks (including pyroclastics) (Permian).12 = Mafic and ultramafic complexes (Paleozoic and Cretaceous).13 = Greywacke (Western sedimentary zone) (Cambrian to Ordovician). Auckland and the AVF In a thick brain fog, crusty eyed and yawning, I sat up in bed at 4:30 am. I was in Auckland, New Zealand. It was still dark outside when I drove to Mount Eden (Maungawhau), where I hiked up a narrow dirt trail lined by tall grass stippled with dew. Coming out of the verdure, my shoes, socks and shorts were soaked through. On top of the hill, a shadow-black grouping of trees blocked the creeping morning light from behind the Hanua Ranges. The burnt orange sunrise, obstructed by cumulous, lit up like a distant mountain wildfire. Auckland city centre was under puffy, lavender-white cirrus clouds, reflecting pastel colours across the harbour. Alone in the cool and crisp pre-dawn air, I viewed the various scoria cones in the Auckland Volcanic Field (AVF) bursting through the city neighbourhoods. Fig. 2. Map of New Zealand showing place names. … Read More

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Great Plains geology: A personal journey

Professor Emeritus Robert F Diffendal, Jr (USA) I grew up in the 1940s and 50s in the eastern US state of Maryland and went to cinemas on my own from the age of six, mostly to see what were then to me exciting western movies. In 1962, I was off to graduate school in the Great Plains state of Nebraska, a place that I pictured in my mind as it had been depicted in some of those films. Imagine my surprise when it looked nothing like the outdoor scenes in most of those films. Silly me, to have thought that films were made as closely as possible to the real subject area. From graduate school in 1962 to now, I achieved my goals and became a geologist and professor, travelling and doing research in the Great Plains and western Central Lowland physiographic provinces, and looking at geology in exotic places like the UK, China, Australia and New Zealand. Fast forward to 2013. I had enough experience and expertise on Great Plains geology by then that I was asked to write a short book of about 35,000 words on the geology of the Great Plains by the director of the Center for Great Plains Studies at the University of Nebraska, Dr Richard Edwards. After visiting and studying sites in Alberta and Saskatchewan in Canada, and in south-western Texas that I had not previously studied, I started working on the book now titled Great Plains Geology that is reviewed in this issue … Read More

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NZ Orphan mine site taken into care

Tanya Piejus (New Zealand) One of New Zealand’s most contaminated sites, the Tui Mine near Te Aroha, is to be cleaned up. The New Zealand budget for 2007 confirmed that NZ$9.88 million was available for the two-year project. The orphan mine site sits on the western flank of Mount Te Aroha, one of Waikato’s highest peaks. In Maori legend, the spirit of Te Mamoe, son of a Bay of Plenty chief, caused a stream of crystal water to flow from the heart of the mountain. However, that stream has become blighted by acid and metals from the abandoned mine workings and is now almost devoid of life. Fig. 1. Polluted water at Tui Mine Tui Mine’s story began in 1967. Norpac Mining Ltd opened it in order to extract metals, including copper, lead and zinc. The mine prospered and the company found several thousand ounces of gold and silver among the ore.  However, unacceptable levels of mercury in the ore soon proved to be the mine’s undoing. The company buying the ore pulled out in 1973 and, two years later, Norpac went into liquidation. Tui Mine was abandoned. Mining equipment was removed for reuse at other sites or was sold for scrap. Left behind was a large pile of larger ore pieces, along with sand-sized crushed ore (tailings). This was dammed to prevent it slipping down the mountainside but, through neglect, the tailings dam became unstable. In 1980, the Hauraki Catchment Board had to build a gravel embankment to stop … Read More

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