HIGH-RESOLUTION PALEOARCHEAN (3.22 GA) COASTAL ECOLOGY: THE ICDP BASE (BARBERTON ARCHEAN SURFACE ENVIRONMENTS) PROJECT
In order to avoid the effects of oxidative weathering (a particular problem in fine-grained strata) and to obtain continuous sections suitable for geochemical and time-series analyses, we will drill five key sections. Nine inclined drillholes, each of 350-600 m length (MD), will investigate (1) conformable terrestrial-marine transitions for environmental proxies, (2) diagnostic lithologies (such as various paleosols, nearshore BIFs, evaporites and basaltic lavas) for their environmental significance, (3) the compositional, facies and morphological variability of thick and laterally extensive microbial mats, and (4) sedimentary and mineralogical responses to surface variables, such as tides, climate, potential meteorite impacts, and radiation, in particular in deep-water strata. Principal questions address the ecology, 3-D morphology and metabolism(s) of the abundant (oxygenic photosynthetic ?) microbial mats, stratigraphic rhythmicity, the redox state (sulfate, redox-sensitive metal isotopes), temperature and composition of ocean water and of early diagenetic fluids, and the relevance and processes of weathering and early diagenesis.