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doi:10.2204/iodp.proc.310.101.2007

Preliminary scientific assessment

During the Expedition 310 Onshore Science Party, emphasis was placed on visual description, measurement of physical properties, and sampling of the cores. Thus, this “Expedition Reports” section of IODP Proceedings volume 310 contains a descriptive framework for subsequent postcruise research.

The primary objectives of Expedition 310 require the use of specialized geochemical techniques, paleomagnetic analyses, and detailed investigation of lithological and biological assemblages. These types of analyses were not conducted during the Onshore Science Party but will be conducted over the coming months at the institutions of the Expedition Scientists as part of their postcruise research.

Fulfillment of the Expedition 310 scientific objectives is as follows:

1. Establish the course of postglacial sea level rise at Tahiti (i.e., define the exact shape of the deglaciation curve for the period 20,000–10,000 cal. y BP).

During the offshore phase, cores were recovered from the last deglacial reef sequence from 40 to 121 m below current sea level. Therefore, most, if not all, of the last deglacial sequence was recovered. During the Onshore Science Party, high-quality coral samples were taken for dating and sea level change investigations, the results of which are expected to fulfill the first objective.

2. Define SST variations for the region over the period 20,000–10,000 cal. y BP.

During the offshore phase, massive coral colonies suitable for paleoclimate studies and spanning most of the last deglacial sequence were recovered in the cores. During the Onshore Science Party, these massive coral colonies were slab-sampled for paleoclimate studies, the results of which are expected to fulfil the second objective.

3. Analyze the impact of sea level changes
on reef growth and geometry.

During the offshore phase, cores were recovered from holes in various water depths and situated on transects in three different areas around Tahiti. Therefore, results of analyses of samples taken during the Onshore Science Party will be interpreted in broad temporal and spacial contexts and studies will consider a wide range of carbonate-secreting organisms as witnesses of ecologic change, which will allow better understanding of the development of the Tahiti reef.

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