Sediments in the ocean basin provide a record of the earth’s climate and tectonic history. Much of the lab research conducted by San José State University Geological Oceanography Professor Dr. Ivano Aiello and his graduate students is focused on analyzing rock outcrops and the deep-sea core sediment record to understand their composition and sources. Dr. Aiello and his marine geology students identify shape, size and composition of the (biogenic) particles that settle through the water column as a result of productivity in the surface waters and the (terrigenous) particles that come from the weathering on the continents. The findings from examining the sediment record collected by international scientific groups such as the Integrated Ocean Discovery Program (IODP) can provide information on terrestrial climate and atmospheric conditions (e.g., rain intensity) as well as tectonic processes such as mountain uplift.
During 2019, Aiello took part in two IODP-NSF (National Science Foundation) deep-seafloor drilling cruises. Both occurred in the Pacific region but in opposite hemispheres.
That summer, he was in the waters off Chile to study the evolution of the Patagonia icefields and the oceanographic and hydrologic change along the northern margin of the Antarctic Circumpolar Current and on the South American continent during the last million years. The Patagonian icefields are an important, yet poorly known component of the global cryosphere. Outside of Antarctica, they are one of the few glaciated regions of the Southern Hemisphere. Previous studies have suggested that the relatively small glaciers that occupy Patagonia are important to global climate because they acted as pacemakers during past episodes of global climate change. This included times when the Gulf Stream was weak or absent (a major oceanic conveyor of heat on our planet). The sediment record collected during the cruise allows, for the first time, the ability to reconstruct the timing and extent of waxing and waning of the ice sheets in Patagonia; the study is currently underway.
In the fall, Aiello sailed on an IODP expedition in the Gulf of California (Guaymas Basin) to investigate the subsurface of this young oceanic basin that is slowly separating the Baja California Peninsula from North America. One of the goals of this deep-sea exploration was to establish the history of precipitation and droughts in the Mesoamerican region for the last two million years, which Aiello’s lab will determine by identifying the sources and types of minerals present in the sediment. Another goal of the expedition was to advance understanding of the conditions that limit life in the deep biosphere. The sediments that fill the ocean basins (two-thirds of the earth’s surface) are some of the largest habitats for life on earth. Yet they pose extreme chemical and physical conditions that would be lethal for life at the surface of our planet. Aiello’s collaboration with an international team of microbiologists aims to shed light on the relationships and interactions between subseafloor sediments and the life they host.