On the Enrichment of Magnetic Heavy Minerals in a Coastal Environment : Exploration, Examination, Explanation

Abstract

In this thesis, an approach for the detailed assessment of magnetic heavy mineral enrichments in a coastal environment using integrated geophysical and sedimentological data is developed, the observed enrichment patterns are interpreted, and their formation mechanisms discussed. Used methods are electromagnetic profiling of the subsurface, close-up seafloor photography, various laboratory techniques to analyze bulk and magnetic grain sizes and mineralogy, and numerical modelling of bi-fractional sediment transport. The studies take place in an exemplary study area in the western Bay of Plenty (New Zealand) with dimensions of 60 km x 7 km in water depths from 2-35 m. Primary instrument is the benthic profiler MARUM NERIDIS III. Overall, the findings of this thesis demonstrate an innovative, effective way to approach an unmapped area and reach detailed results with conclusive interpretations in a relatively short time. It shows the conditions under which natural sorting patterns due to size and density develop along the coast. The basic formation mechanisms are applicable to other areas in similar coastal settings and for a diverse range of heavy minerals.