In 2007-2008 the ANtarctic DRILLing Program completed the second drilling in the Southern McMurdo Sound region.

The core recovered several stratigraphic intervals from early Miocene to Pliocene and it collected a variety of terrigenous clastic lithologies; the constant volcanic constituent let to achieve a series of absolute ages by ⁴⁰Ar-³⁹Ar method.

The clay mineral assemblages of the 1138,54 m thick sedimentary succession have been analyzed to reconstruct the paleoclimate and the glacial history of this region of Antarctica. Sampling has been performed collecting 78 samples, one sample every 10 m, along drill core.

XRD analyses on the clay fraction and SEM-FESEM observations on the whole rocks have been performed. The clay mineral assemblages are dominated by illite and smectite, with minor chlorite and kaolinite. Illite and smectite are negatively correlated; smectite reaches values up to 100% from ca. 800 mbsf down to the bottom. Textural investigations indicate that authigenic and detrital smectites occur throughout the whole core. Smectites, below 800 mbsf, are predominantly authigenic and reach the highest percentages. Authigenic smectites show a significant deviation toward trioctahedral compositions, since probably they formed from the alteration of volcanic material (in part, pyroxenes, glasses), which produced the coexistence of tri- and dioctahedral areas; they occur as coatings on detrital grains and as replacements of glass shards. Detrital smectites, instead, show a dioctahedral and more variable nature.

Since clay minerals represent indicators of paleoclimate only when they are of detrital origin, the large abundance of authigenic smectites within the whole core requires that paleoenvironmental and paleoclimatic reconstruction must be approached with care.