Palaeomagnetic and physical properties records from Foulden Maar, New Zealand

This dataset includes palaeomagnetic inclination directions and density, reflectance (CIEL*a*b*) and red intensity (RGB) measurements from 100 metres of diatomaceous lake sediments from the Oligocene/Miocene Foulden Maar, New Zealand.

Response of nannoplankton to major changes in sea-surface temperature at the South Chatham Rise, southeastern New Zealand

A high-resolution history of paleoceanographic changes in the subpolar waters of the southern margin of the Subtropical Convergence Zone during the last 130 kyr, is present in foraminiferal assemblages of DSDP Site 594. The foraminifera indicate that sea-surface temperatures during the Last Interglacial Climax were warmer than today, and that between substage 5d through to the end of isotope stage 2, temperatures were mostly cooler than Holocene temperatures. The paleotemperatures suggest that (1) the Subtropical Convergence was located over the site during substage 5e, later moving further north, then moving southwards to near the site during the Holocene, and (2) the Polar Front was positioned over the Site during glacial stages 6, 4, 2 and possibly parts of stage 3. Several major events are indicated by the nannofloral assemblages during these large changes in sea-surface temperature and associated reorganization of ocean circulation. First, the time-progressive trends between E. huxleyi and medium to large Gephyrocupsa are unique to this site, with E. huxleyi dominating over medium Gephyrocupsa during stages 5c-a, middle part of stage 4 and after the middle point of stage 3. This unusual trend may (at least partly) be caused by the shift of the Polar Front across the site. Second, upwelling flora (E. huxleyi and small placoliths) increase in abundance during stages 1, 3 and 5, suggesting that upwelling or disturbance of water stratification took place during the interglacials. Thirdly, there are no significant differences between the distribution patterns of the various morphotypes of medium to large Gephyrocupsu, and the combined value of all medium Gephyrocupsu increases in abundance during glacials (stages 2 and 4 and the end of stage 6), similar to the abundance trends in benthic foraminifera. Finally, subordinate nannofossil taxa also show distinctive climatic trends during the last glacial cycle: (1) Syrucosphaera spp. are present in increased abundance during warmer extremes in climate (substages 5e, 5a, and stage 1); (2) Coccolithus pelagicus and Culcidiscus leptoporus dominate the subordinate nannofossil taxa, and their relative proportions seem to provide a useful paleoceanographic index, with C. pelagicus dominating when the Polar Front Zone is over the site (stages 6, 4 and 2), whilst C. leptoporus is relatively more abundant when the STC is positioned over the site (stages 1 and 5e). Increased abundance of C. pelagicus also can indicate intensified coastal upwelling.

In-situ geotechnical measurements with the dynamic penetrometer Nimrod on the continental shelf off the Coromandel Peninsula, New Zealand

We tested the ability of a small dynamic penetrometer, Nimrod, to infer geotechnical properties of sediment mixtures in the inner shelf. The penetrometer is light and easy to operate, and its operation by scuba divers ensures a greater degree of precision than ship-based penetrometer deployments. We have studied selected positions along a sorted bedform (~ 100 m wide) on the continental shelf off the Coromandel Peninsula close to Tairua, North Island of New Zealand, and additionally took sediment samples at the exact positions of penetrometer impact, also by scuba divers. The derived dynamic penetrometer signatures (i) measured deceleration of the probe and estimated quasi-static bearing capacity as a measure of sediment strength, (ii) reflected changes in grain-size distribution ranging from very fine to very coarse sands, and (iii) revealed the uppermost seafloor stratification (top layer 2-6 cm) potentially being an indicator for sediment dynamics. In this manner, the device proved to be suitable for spatially fine-scaled surveys using divers' support and might deliver complementary information about sediment dynamics, in this case sorted-bedform maintenance.

Nimrod (dynamic penetrometer) measurements of a sandbar at Raglan, New Zealand in 2009

Dynamic penetrometer data obtained with the Nimrod penetrometer (MARUM). Data is presented as (i) penetration depth (including for different layers if present), (ii) measured deceleration and (iv) estimated quasi-static bearing capacity including range of uncertainty due to the processing method. Lat/Long coordinates are given.