Northland ophiolite, New Zealand, and implications for plate- tectonic evolution of the southwest Pacific

The Northland ophiolite and coeval ocean-floor sedimentary rock form the Northland allochthon obducted from the northeast onto New Zealand in the late Oligocene. The ophiolite was probably emplaced as a single sheet and separated into individual massifs during subsequent movement of the allochthon. Chemically, the bulk of the igneous rocks are normal mid-ocean-ridge basalts, but the ophiolite also includes a younger suite of hornblende modal within-plate alkalic rocks believed to represent seamounts. Two alternative models, one involving a subduction flip, the other involving continuous westward subduction, are proposed to account for the obduction of the upper part of the Northland ophiolite. The oceanic crust from which the ophiolite originated was formed simultaneously with Tasman Sea spreading on the western rim of a once much larger South Fiji plate assemblage. -Authorslink_to_subscribed_fulltex

Detecting short-term evolution of Etnean scoria cones: a LIDAR-based approach

The 2001 and 2002–2003 flank eruptions on Mount Etna (Italy) were characterized by intense explosive activity which led to the formation of two large monogenetic scoria cones (one from each eruption) on the upper southern flank of the volcano. Continuous monitoring of Etna, especially during flank eruptions, has provided detailed information on the growth of these cones. They differ in genesis, shape, and size. A set of high resolution (1 m) digital elevation models (DEMs) derived from light detection and ranging (LIDAR) data collected during four different surveys (2004, 2005, 2006, and 2007) has been used to map morphology and to extract the morphometric parameters of the scoria cones. By comparing LIDARderived DEMs with a pre-eruption (1998) 10 m DEM, the volume of the two scoria cones was calculated for the first time. Comparison of the LIDAR-derived DEMs revealed in unprecedented detail morphological changes during scoria cone degradation. In particular, the morphologically more exposed and structurally weaker 2002–2003 cone was eroded rapidly during the first few years after its emplacement mainly due to gravitational instability of slopes and wind erosion