Woods Hole Oceanographic Institution

About: Woods Hole Oceanographic Institution is a nonprofit organization based out in Falmouth, Massachusetts, United States. It is known for research contribution in the topics: Population & Mantle (geology). The organization has 5685 authors who have published 18396 publications receiving 1202050 citations. The organization is also known as: WHOI.

Kinematics and geometry of active detachment faulting beneath the Trans-Atlantic Geotraverse (TAG) hydrothermal field on the Mid-Atlantic Ridge

Abstract: Newly acquired seismic refraction and microearthquake data from the Trans-Atlantic Geotraverse (TAG) segment of the Mid-Atlantic Ridge at 26°N reveal for the first time the geometry and seismic character of an active oceanic detachment fault. Hypocenters from 19,232 microearthquakes observed during an eight month ocean bottom seismometer deployment form an ∼15-km-long, dome-shaped fault surface that penetrates to depths >7 km below the seafloor on a steeply dipping (∼70°) interface. A tomographic model of compressional-wave velocities demonstrates that lower crustal rocks are being exhumed in the detachment footwall, which appears to roll over to a shallow dip of 20° ± 5° and become aseismic at a depth of ∼3 km. Outboard of the detachment the exhumed lithosphere is deformed by ridge-parallel, antithetical normal faulting. Our results suggest that hydrothermal fluids at the TAG field exploit the detachment fault to extract heat from a region near the crust-mantle interface over long periods of time.

Animal behaviour: Elephants are capable of vocal learning

Abstract: Two animals coin unexpected sounds as a surprising form of social communication. The ability of humans, birds, bats and dolphins to imitate the calls of other members of their species may have evolved to restore bonds when animals separate and reunite. If so, vocal learning might be seen in other social species. The behaviour of a male African elephant at Basel Zoo suggests that non-primate mammals can use imitation. After spending 18 years with two female Asian elephants, Calimero makes the chirping sounds thought to be the prerogative of Asian elephants. Another African elephant, a female called Mlaika, mimics a more unlikely sound: the rumble of trucks on the nearby Nairobi–Mombasa highway. Mlaika's truck-like calls can be heard on nature.com as Supplementary Information. There are a few mammalian species that can modify their vocalizations in response to auditory experience1 — for example, some marine mammals use vocal imitation for reproductive advertisement, as birds sometimes do. Here we describe two examples of vocal imitation by African savannah elephants, Loxodonta africana, a terrestrial mammal that lives in a complex fission–fusion society2. Our findings favour a role for vocal imitation that has already been proposed for primates, birds, bats and marine mammals: it is a useful form of acoustic communication that helps to maintain individual-specific bonds within changing social groupings3,4.

Palaeo-oceanography: Deepwater variability in the Holocene epoch

Abstract: The conversion of surface water to deep water in the North Atlantic results in the release of heat from the ocean to the atmosphere, which may have amplified millennial-scale climate variability during glacial times1 and could even have contributed to the past 11,700 years of relatively mild climate (known as the Holocene epoch)2,3,4. Here we investigate changes in the carbon-isotope composition of benthic foraminifera throughout the Holocene and find that deep-water production varied on a centennial–millennial timescale. These variations may be linked to surface and atmospheric events that hint at a contribution to climate change over this period.

Morphology and tectonics of the inner rift valley at lat 36°50′N on the Mid-Atlantic Ridge

Abstract: A segment of the inner rift valley of the Mid-Atlantic Ridge was investigated in detail from the American submersible Alvin . Fifteen traverses were made across the floor and up the first major fault scarps in the valley walls. The asymmetric morphology of the inner floor is found to be the primary result of volcanic activity modified by tectonic activity. Analysis of the tectonic features revealed that the rift is evolving within a single stress field that has its least principal strain axis (the compressional axis) aligned with the valley axis of N20°E. This is in contrast to the direction normal to plate divergence (N0°E). The tectonic elements in the inner floor are primarily vertically dipping tension fractures, whereas the fault scarps of the flanking walls are closer to a 60° dip and reflect a component of downdip shear. The information base obtained from Alvin was broadened with information collected in the area with more conventional techniques. Through an analysis of this information, primarily the topography, it was possible to extrapolate the detailed observations obtained from the submersible to intervening areas to produce a comprehensive geological interpretation of the study area. An evolutionary model was developed which suggests that the inner rift is a product of axial volcanic activity. Shortly after formation, the original volcanic edifice is modified by vertical collapse, which leads to a reduction of the bottom relief. This process is reversed in the outer portions of the valley as uplift begins. Tensional extension changes into vertical shear as the volcanic blocks are incorporated into the walls and elevated. During the various stages of uplift, readjustment takes place on the terraces, which results in the preservation of the original volcanoes as recognizable units. This model, which spans 180,000 yr of inferred time, is examined in detail in an attempt to identify its weaknesses as well as to delineate the specific factual constraints upon which it is built. Alternate interpretations are proposed and tested in a similar fashion; the result is the identification of key problems that need to be solved.