Researchers analysed the age and chemistry of lavas from the base of the western Aleutian volcanic arc, sampled across roughly 700 kilometres, to work out when subduction began there. The results show that Aleutian subduction started at least 56 million years ago, with early lavas resembling those formed during the onset of subduction in the … Read more…
Deep-sea carbonates constitute the primary deep carbon reservoir, playing a critical role in regulating the long-term global carbon cycle. Reconstructing the temporal evolution of carbonate flux to the seafloor requires estimating the changes in carbonate compensation depth (CCD), a key proxy, revealing the depth where the rate of calcium carbonate supply from biogenic ooze equals … Read more…
Recent dredging of a 100 km long ridge along the northernmost part of the Louisiade Plateau (LP) recovered serpentinized peridotites, MORB (mid-ocean-ridge basalt) and volcaniclastic breccia–conglomerates. Clinopyroxene, Cr-spinel and bulk rocks show that the serpentinites are harzburgites to dunites, whereas hornblende phenocrysts from volcaniclastic rocks reflect hydrous, andesitic volcanism. The association of MORB, depleted mantle rocks … Read more…