Artifact geochemistry demonstrates long-distance voyaging in the Polynesian Outliers.

Although the peopling of Remote Oceania is well-documented as a general process of eastward migrations from Island Southeast Asia and Near Oceania toward the archipelagos of Remote Oceania, the origin and the development of Polynesian societies in the Western Pacific (Polynesian Outliers), far away from the Polynesian triangle, remain unclear. Here, we present a large-scale geochemical sourcing study of stone artifacts excavated from archeological sites in central Vanuatu, the Solomon Islands, and the Caroline Islands and provide unambiguous evidence of multiple long-distance voyages, with exotic stone materials being transported up to 2500 kilometers from their source. Our results emphasize high mobility in the Western Pacific during the last millennium CE and offer insights on the scale and timing of contacts between the Polynesian Outliers, their neighbors in the Western Pacific, and societies of Western Polynesia.

Caldera resurgence during the 2018 eruption of Sierra Negra volcano, Galápagos Islands.

Recent large basaltic eruptions began after only minor surface uplift and seismicity, and resulted in caldera subsidence. In contrast, some eruptions at Galápagos Island volcanoes are preceded by prolonged, large amplitude uplift and elevated seismicity. These systems also display long-term intra-caldera uplift, or resurgence.

Acid digestion on river influenced shelf sediment organic matter: Carbon and nitrogen contents and isotopic ratios.

Rationale: Natural stable isotope ratios (δ C and δ N values) and associated elemental concentrations (i.e. total organic carbon and total nitrogen contents) preserved in marine sediments are frequently used for the determination of paleo-environmental processes such as the origin of organic matter.

Stream chemical dynamic and metal accumulation in a temperate watershed affected by agricultural practices (Penzé, NW France).

Rationale: Understanding the fate of metals in agricultural land is an important issue for agronomic sustainability. This study aimed at quantifying the export/retention of metals in a temperate watershed subject to important manuring activities.

Methods: The chemical composition of the Penzé stream was examined at high resolution during a 1-year study in 2012.

Biogeochemical insights into microbe-mineral-fluid interactions in hydrothermal chimneys using enrichment culture.

Active hydrothermal chimneys host diverse microbial communities exhibiting various metabolisms including those involved in various biogeochemical cycles. To investigate microbe-mineral-fluid interactions in hydrothermal chimney and the driver of microbial diversity, a cultural approach using a gas-lift bioreactor was chosen. An enrichment culture was performed using crushed active chimney sample as inoculum and diluted hydrothermal fluid from the same vent as culture medium.

Microbial colonization of basaltic glasses in hydrothermal organic-rich sediments at Guaymas Basin.

Oceanic basalts host diverse microbial communities with various metabolisms involved in C, N, S, and Fe biogeochemical cycles which may contribute to mineral and glass alteration processes at, and below the seafloor. In order to study the microbial colonization on basaltic glasses and their potential biotic/abiotic weathering products, two colonization modules called AISICS ("Autonomous in situ Instrumented Colonization System") were deployed in hydrothermal deep-sea sediments at the Guaymas Basin for 8 days and 22 days. Each AISICS module contained 18 colonizers (including sterile controls) filled with basaltic glasses of contrasting composition.