ALBERT

Description: Up until the late 1980s geology contributed very little to the study of tsunamis because most were generated by earthquakes which were mainly the domain of seismologists. In 1987–88 however, sediments deposited as tsunamis flooded land were discovered. Subsequently they began to be widely used to identify prehistorical tsunami events, providing a longer-term record than previously available from historical accounts. The sediments offered an opportunity to better define tsunami frequency that could underpin improved risk assessment. When over 2200 people died from a catastrophic tsunami in Papua New Guinea (PNG) in 1998, and a submarine landslide was controversially proven to be the mechanism, marine geologists provided the leadership that led to the identification of this previously unrecognized danger. The catastrophic tsunami in the Indian Ocean in 2004 confirmed the critical importance of sedimentological research in understanding tsunamis. In 2011, the Japan earthquake and tsunami further confirmed the importance of both sediments in tsunami hazard mitigation and the dangers from seabed sediment failures in tsunami generation. Here we recount the history of geological involvement in tsunami science and its importance in advancing understanding of the extent, magnitude and nature of the hazard from tsunamis.

Description: Microanalysis can provide rapid, quantitative characterization of mineral systems that complements the field- and core-scale observations traditionally made in ore deposits. We review recent innovations in microanalytical procedures and their application to studies of ore deposits. Case studies are presented examining how microanalysis can provide constraints on macroscopic processes within mineral systems. Synchrotron X-ray fluorescence shows centimetre-scale chemical variations associated with proximity to mineralization in samples from Sunrise Dam Gold Mine, Western Australia. Pseudomorphs of igneous plagioclase and chemically driven recrystallization interpreted from electron backscatter diffraction suggest that the system was dominated by fluid-driven brecciation with very little shearing. Both the fluid chemistry and fluid pressure evolved during a protracted sequence of vein formation and alteration accompanying gold mineralization. A second case study of sulphide mineralogy at the Mt Keith nickel sulphide deposit, Western Australia demonstrates how X-ray computed tomography combined with trace element mapping can constrain the chemistry and dynamics of magmatic systems. Large-scale interaction between silicate and sulphide melts, shown by homogenous palladium enrichment in pentlandite, leads to a large proportion of globular ores with a high nickel content. Increasing use of microanalysis in ore deposit geology is resulting in the constant reassessment of established models for ore genesis though a combination of micro- and macroscale datasets.

Description: This paper focuses on the submerged landscapes of the southern North Sea, an area often referred to as Doggerland, which was inundated as a result of relative sea-level rise at the start of the Holocene. The timing, pattern and process of environmental changes and the implications for prehistoric (Mesolithic) human communities living in this area have long been a subject of debate and discussion. Recent developments in marine geophysics have permitted the mapping of the pre-submergence landscape, leading to the identification of landforms including river channels and other contexts suitable for the preservation of palaeoecological records. The paper describes multi-proxy (pollen, foraminifera, plant macrofossil and insect) palaeoenvironmental analyses of a vibrocore sequence recovered from a palaeochannel feature c. 80 km off the coast of eastern England. The palaeochannel preserves sediments of Late Pleistocene and Holocene age (MIS2/1); the record suggests that channel incision, probably during the early Holocene, was followed by a phase of peat formation (c. 9–10 cal ka BP) indicating paludification and the subsequent reactivation of the channel (c. 9–6 cal ka BP), initially under freshwater and increasingly brackish/saline conditions, and a final transition to full marine conditions (6–5 cal ka BP). The pollen, macrofossil and beetle records indicate the presence of pre-submergence deciduous woodland, but detailed interpretation of the data is hindered by taphonomic complications. The paper concludes with a discussion of the problems and potentials of using palaeoenvironmental data to reconstruct complex patterns of environmental change across Doggerland in four dimensions, and considers specific questions concerning the implications of such processes for Mesolithic human communities.