Pituffik Titanium Project: Results of 2016 Fieldwork. Onshore sampling and sedimentology

Samuel Weatherley, Peter N. Johannessen

Publikation: Bog/rapportRapport (offentligt tilgængelig)

Abstrakt

In July and August 2016 a geological sampling and observational program was conducted on raised and active beaches close to Moriusaq in the Pituffik region of North West Greenland (figure 1). The purpose of the investigation was to (i) sample onshore sediment units that are known to hold high concentrations of ilmenite sand, and (ii) understand the processes that are key to the formation of the placer deposit. The work was conducted by GEUS for FinnAust Mining Plc.

The results presented in this report build on recent onshore sampling activities (Weatherley, 2015) and offshore geophysical surveys (Jensen & Rödel, 2015), and complement an onshore GPR survey (Jakobsen et al, 2016), near-shore sediment echo sounding survey (Jensen et al., 2016) and offshore sampling program (Bennike et al, 2016) that were run concurrently during the 2016 field season. During this field season, a total of 244 samples were collected using an auger drill and from hand-dug trenches. The maximum depth below the surface from which material was taken is 1.1 m. Additionally, sedimentary profiles were studied in stream cuts, cliff sections and in trenches.

The beach systems were observed to be enriched to variable degrees in metallic sand. In-field estimates suggest that the metallic fraction can be higher than 80%, although metallic fractions of 20-40% are more common. Cliff sections reveal that the raised beach systems can have thicknesses in excess of 3 m. This thickness, however, is not necessarily representative of the whole study area. For example, the sediment body making up the angle foreland at Iterlak is possibly closer to 12 m in thickness. Additional work is needed to make a regional determination of the sediment thickness and estimate sediment volumes.

New field observations revealed that ilmenite is concentrated in placer system by a positive feedback loop involving (i) erosion of previously enriched raised beach sediments and transportation of those sediments to active beaches, (ii) further refinement of the sediment on active beaches by wave action and longshore currents, (iii) preservation of ilmenite-enriched active beach sediment by long-term change in relative sea level. Fluvial systems that cut through the raised beaches are thought to be the most important mechanism for transporting ilmenite-enriched sediment to the active beaches. Many of the onshore deposits have been preserved by an overall fall in relative sea level. New observations show that the overall marine regression was punctuated by short periods of marine transgression. These observations lend support to suggestions from earlier work (Jensen & Rödel, 2015) that additional ilmenite-rich beach systems can be found offshore.
OriginalsprogEngelsk
UdgivelsesstedCopenhagen
ForlagGEUS
Rekvirerende organisationFinnAust Mining Plc
Antal sider105
Vol/bind2016
DOI
StatusUdgivet - 15 feb. 2017

Publikationsserier

NavnDanmarks og Grønlands Geologiske Undersøgelse Rapport
ForlagGEUS
Nr.69
Vol/bind2016

Emneord

  • Greenland

Programområde

  • Programområde 4: Mineralske råstoffer

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