TECTONIC IMPLICATIONS OF PALEOENVIRONEMT FROM DEEP SEA LIMESTONE AND PLANKTONIC FORAMINIFERA OF THE NEW CALEDONIA BASIN FROM DSDP SITE 206

The tectonics of the New Caledonia region are complex and its true nature is not agreed upon by scientists. The origin of the subjecting plate, its location and the direction of subduction are debated with various features not fitting into geologic models. To better constrain the deformation, planktonic foraminifera in Paleocene and Eocene pelagic limestones from DSDP site 206 are under study. By studying the planktonic foraminifera within the Paleocene and Eocene rocks found at DSDP site 206 a more precise correlation between the rocks of the New Caledonia Basin and the “Globigerina Limestones” of the island of New Caledonia can be produced. Further, a paleoceanographic model based on the abundance of specific planktonic foramifera taxa can be employed to better understand the interaction of tectonic and paleoceanographic processes.

Planktonic Foraminifera have distinct time frames they lived in due to their sensitivity to ocean temperatures, depth and salinity. By studying the planktonic foraminifera within the Paleocene and Eocene epochs found at DSDP site 206 and fitting the results into a paleoceanographic model, a better idea of tectonic plate confluence can be deduced. A probable and important correlation and better understanding of the paleoceanography will be attained for this time period and serve specifically to connect the New Caledonia trough with onland exposures. The initial hypothesis is the Globigerina studied in this core will correlate with the Globigerina seen on land in New Caledonia at locations such as Rocher et Voiles, Illot Brun Section, Noumea and Koumac indicating the forced tectonic uplift in this region. Thin sections are to be analyzed from DSDP site 206 under a petrographic microscope for any Paleocene-Eocene planktonic foraminifera. The identified taxa will then be compared to paleoceanographic models of the South Pacific in order to better constrain the tectonic deformation of the region.

Initial examination of the 66 thin sections produced indicate these samples do correlate with onland exposures; comprising of 70% or more of Globigerina species, what is to be expected if these samples are to match those seen at New Caledonia. Since the samples are so densely packed with Globigerina, a 300 point count using a mechanical stage will be used to ensure a thorough examination of each slide.