small sized species from the fossil record. Using the exceptionally good fossil record of New Zealand Recent and Cenozoic Mollusca, we use a novel approach to estimate the magnitude of the bias against small body size and the effect of this bias on completeness of the fossil record. Our database of 3907 fossil species represents an original living pool of 9086 species, from which 36% have been removed by size culling, 27% from the smallest size class (
offshore west coast to offshore east coast. It overlaps in part with the original 1:250 000 Mt Cook, Hokitika, Hurunui & Christchurch geology maps compiled in the 1960s (Gair 1967, Warren 1967, Gregg 1964, Suggate 1972). Aoraki’s improvements over the earlier maps include the detail of greywacke and schist mapping, more extensive mapping of Quaternary deposits in hill and mountain country, and the recognition and detail of numerous new faults and folds, many demonstrably active. As with other QMAPs, the primary emphasis is compilation of existing data, from published (e.g. maps, papers) and unpublished (e.g. reports, theses) sources. Additional mapping as part of QMAP aimed to fill data gaps, ensure uniform levels of data detail, or resolve major conflicts of interpretation. The map has been compiled at 1:50 000 scale into a Geographic Information System (GIS), but with sufficient generalisation for legible presentation at 1:250 000 scale. New mapping has added much improved understanding of the Rakaia (Torlesse) terrane. Greywacke/schist mapping emphasises textural zonation (t.z.) rather than the mineral zonation (chlorite, biotite, garnet) of the earlier maps, although the new map also depicts mineral isograds. Alpine schist fabrics and isograds vary considerably along the plate boundary, and schist units are not parallel to the Alpine Fault. Bedding trends in t.z.1 greywacke are emphasised with formlines. A regional swing in bedding strike (from 320° to 030°) commences around 60 km SE of the Alpine Fault, mimicking the oroclinal bend of Mesozoic terranes in the southern South Island. Bedding faces mainly west or southwest, with locally eastward-facing, overturned, sections up to 10 km thick. Steeply plunging folds become progressively tighter and with shorter wavelength approaching the Alpine Fault. En echelon northeast-striking, reverse-dextral oblique-slip faults dipping 40-60° NW are common in the central Southern Alps. Steeply plunging folds are transected, overthrust and rotated by late Cenozoic displacement on these faults. Relatively few changes have been made to the mapping of Cretaceous to Pliocene sediments, a tribute to the quality of Cenozoic stratigraphy and paleontology in the 1960s. However, the QMAP Aoraki units and legend contain more lithostratigraphic information, reflecting the Cretaceous-Cenozoic transgression and regression in more detail than on the earlier maps. Quaternary map units on QMAP Aoraki include scree, colluvium & landslide debris, in addition to the glacial and fluvial deposits emphasised by earlier maps. Faults and folds are depicted as active only where there is good geomorphic evidence of late Quaternary deformation. Other structures, particularly those outcropping in the mountainous Southern Alps lack of evidence of activity, rather than showing evidence of inactivity. POSTER LATE CRETACEOUS EUSTASY AND THE EAST COAST BASIN - THE GOOD <strong>NEW</strong>S! James S. Crampton 1 ,PoulSchiøler 2 & Lucia Roncaglia 3 1 Institute of Geological & Nuclear Sciences, PO Box 30368, Lower Hutt. 2 Geol. Surv. Denmark & Greenland, Ø. Voldgade 10, DK-1350 Copenhagen, Denmark. 3 Danish Oil & Natural Gas A/S, Agern Alle 24-26, DK-2970 Hørsholm, Denmark. (j.crampton*gns.cri.nz) Distinguishing tectonic from supposedly eustatic Upper Cretaceous sequences is highly problematic for New Zealand successions that are structurally and/or stratigraphically complex and remote from well-studied Northern Hemisphere localities. The problem is largely one of resolution in chronostratigraphic correlation, and conclusions may vary depending on philosophies and approaches to correlation. A complementary study (Schiøler et al., this volume), based on palynofacies analysis and zonal correlations, found little evidence for Late Cretaceous eustatic signatures in the East Coast Basin. Here we take a different approach that employs multidimensional graphic correlation using constrained optimization (CONOP) to derive a high-resolution correlation for 15 Coniacian-Maastrichtian sections in the East Coast Basin. The resulting composite section, based on 398 well-constrained lowest- or highestoccurrence bioevents, yields 183 event levels and an average chronostratigraphic resolution of approximately 142 Kyr. The age of the composite is calibrated using seven dated bioevents; two of these events are tied to geochemical or paleomagnetic datums. CONOP cannot resolve unconformities that occur across all sampled sections. We suggest, however, that such unconformities are represented by large event-clusters at single composite levels, and 13 such event-clusters are identified. Of these, 10 lie within hiatus intervals recorded from the New Jersey coastal plain and interpreted as eustatic sequence boundaries; the probability of this coincidence arising by chance alone is c. 8%. Although provisional, these results suggest that high resolution quantitative stratigraphy can provide a potent tool for the resolution and global correlation of stratigraphic sequences. Furthermore, our findings add support for recent studies that have argued for the presence of Late Cretaceous eustatic sea-level changes. 50 th <strong>Kaikoura</strong>05 -19- <strong>Kaikoura</strong> <strong>2005</strong>
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