Uncovering the mineralogy of the Australian Continent: the AuScope National Virtual Core Library. A national hyperspectrally derived drill core archive
The National Virtual Core Library (NVCL) is a unique mineralogical and image record of thousands of drill cores from more than 50 years of exploratory drilling across the Australian continent. Just over 10 years ago, and in order to maintain Australia's international competitiveness, the federal government established the National Collaborative Research Infrastructure Strategy (NCRIS) to facilitate research, create new applications and build wealth across a range of economic sectors. This included the earth and geospatial sciences and led to the establishment of AuScope, a not for profit entity to manage the funds (www.auscope.org) AuScope comprises a suite of components embracing technologies and capabilities in data acquisition, management, modelling and simulation across the geospatial and geoscience spectrum for the benefit of all Australians. One of AuScope's components is the NVCL to 'bring alive' and make more accessible decades of exploratory drilling into the Australian continent by private and public entities. Through enlightened legislation and significant past investment, huge physical drill core archives from past and present exploration are preserved in every State and Territory across Australia. However, these are essentially static assets, require travel to access and comprise analogue records, still requiring on the spot subjective interpretation. The NVCL goal is to image and digitise these cores, objectively extract their mineralogy and publish their content online, thus exposing or uncovering the mineralogical composition of the top 2 km or so of the continent's crust. The mineralogical mapping is achieved using innovative non invasive, robotic, visible and infrared spectroscopy and semi automated software. The rebirthing of thousands of these cores in this way is intended to foster new applications and new understanding about Australia's natural resources and environment. Exposing the mineralogical content and increasing access also provide unparalleled resources and data for teaching and in service training in a seamless manner across the entire continent. Furthermore, rather than duplicate those enormous past drilling investments with new drilling, the project aims to foster learning from those past efforts and expenditures so that future resource exploration is progressively better targeted. This special issue brings together a series of papers drawn from the wide body of research and development undertaken on the underpinning technologies and, ultimately more importantly, the applications, so far, of the ongoing NVCL Project. The reader should consider these as examples only of the very wide range of topics and opportunities that this unique resource offers all earth scientists. Other examples will be found in conference proceedings and professional papers in a variety of journals. The NVCL view of mineral spectroscopy is substantially different, by necessity, from most of its predecessors. The NVCL is not guided by narrowly defined mineral deposit environments, such as just porphyry systems. Taking a national and highly optimistic view, our aim is to be able to characterise all the (spectroscopically active) minerals likely to be encountered in day to day, multi commodity exploration and development across a whole continent's geology; no mean undertaking! Given the appropriate spatial and spectral resolution, visible and infrared reflectance spectroscopy is one of the most powerful and information rich sources of mineralogical information. Furthermore, today it can be undertaken with little sample preparation, rapidly and at low acquisition cost to deliver near real time results. In the earth sciences, mineral spectroscopy is far from new, and today's endeavours can be traced back to pioneering laboratory work by Hunt and Salisbury (Graham Hunt was Australian born) co authors and many others, published during the 1970s and largely in the journals Modern Geology and Geophysics (e.g. Hunt, 1979; Hunt Salisbury, 1970; Hunt Salisbury, 1976; Hunt, Salisbury, and Lenhoff, 1971; Salisbury, 1989) This work, and that of many others, led to interest in the use of shortwave infrared spectroscopy, first with luggable, then with portable, then hand held instruments (such as the PIMA, Terraspec and oreXpress instruments) focusing on the hard to recognise clay minerals formed during hydrothermal alteration of certain mineral deposits, most notably porphyry and epithermal systems. These underpinning studies also drew attention to what might be possible with airborne and spaceborne remote sensing. While these early developments were essential steps (and we would not be where we are today without them) the research was commonly motivated by grants to government and academia from space focused agencies and less on asking, 'If, as a geologist, I could design a remote, non invasive mineralogical sensing system, what would it need to be? Of course, the answer to this has to be modulated by the state of technology at the time, but fundamentally what Australia has been able to bring to the general advancement of mineralogical sensing has been an economy that is very resource focused and a mining sector ready to embrace new