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.

Abrupt Climate Events 500,000 to 340,000 Years Ago: Evidence from Subpolar North Atlantic Sediments

Abstract: Subpolar North Atlantic proxy records document millennial-scale climate variations 500,000 to 340,000 years ago. The cycles have an approximately constant pacing that is similar to that documented for the last glacial cycle. These findings suggest that such climate variations are inherent to the late Pleistocene, regardless of glacial state. Sea surface temperature during the warm peak of Marine Isotope Stage 11 (MIS 11) varied by 0.5° to 1°C, less than the 4° to 4.5°C estimated during times of ice growth and the 3°C estimated for glacial maxima. Coherent deep ocean circulation changes were associated with glacial oscillations in sea surface temperature.

Widespread active detachment faulting and core complex formation near 13° N on the Mid-Atlantic Ridge

Abstract: Oceanic core complexes are massifs in which lower-crustal and upper-mantle rocks are exposed at the sea floor1,2,3. They form at mid-ocean ridges through slip on detachment faults rooted below the spreading axis2,3,4,5,6. To date, most studies of core complexes have been based on isolated inactive massifs that have spread away from ridge axes. Here we present a survey of the Mid-Atlantic Ridge near 13° N containing a segment in which a number of linked detachment faults extend for 75 km along one flank of the spreading axis. The detachment faults are apparently all currently active and at various stages of development. A field of extinct core complexes extends away from the axis for at least 100 km. Our observations reveal the topographic characteristics of actively forming core complexes and their evolution from initiation within the axial valley floor to maturity and eventual inactivity. Within the surrounding region there is a strong correlation between detachment fault morphology at the ridge axis and high rates of hydroacoustically recorded earthquake seismicity. Preliminary examination of seismicity and seafloor morphology farther north along the Mid-Atlantic Ridge suggests that active detachment faulting is occurring in many segments and that detachment faulting is more important in the generation of ocean crust at this slow-spreading ridge than previously suspected.

Oxidative inactivation of cytochrome P-450 1A (CYP1A) stimulated by 3,3',4,4'-tetrachlorobiphenyl: production of reactive oxygen by vertebrate CYP1As.

Abstract: Microsomal cytochrome P-450 1A (CYP1A) in a vertebrate model (the teleost fish scup) is inactivated by the aryl hydrocarbon receptor agonist 3,39,4,49-tetrachlorobiphenyl (TCB). Here, the mechanism of CYP1A inactivation and its relationship to reactive oxygen species (ROS) formation were examined by using liver microsomes from scup and rat and expressed human CYP1As. In vitro inactivation of scup CYP1A activity 7-ethoxyresorufin O-deethylation by TCB was time dependent, NADPH dependent, oxygen dependent, and irreversible. TCB increased microsomal NADPH oxidation rates, and CYP1A inactivation was lessened by adding cytochrome c. CYP1A inactivation was accompanied by loss of spectral P-450, a variable loss of heme and a variable appearance of P-420. Rates of scup liver microsomal metabolism of TCB were , 0.5 pmol/ min/mg, 25-fold less than the rate of P-450 loss. Non-heme iron chelators, antioxidant enzymes, and ROS scavengers had no influence on inactivation. Inactivation was accelerated by H2O2 and azide but not by hydroxylamine or aminotriazole. TCB also inactivated rat liver microsomal CYP1A, apparently CYP1A1. Adding TCB to scup or rat liver microsomes containing induced levels of CYP1A, but not control microsomes, stimulated formation of ROS; formation rates correlated with native CYP1A1 content. TCB stimulated ROS formation by baculovirus-expressed human CYP1A1 but not CYP1A2. The results indicate that TCB uncouples the catalytic cycle of CYP1A, ostensibly CYP1A1, resulting in formation of ROS within the active site. These ROS may inactivate CYP1A or escape from the enzyme. ROS formed by CYP1A1 may contribute to the toxicity of planar halogenated aromatic hydrocarbons.

Breakup of the Newfoundland Iberia rift

Abstract: The Newfoundland–Iberia rift is considered to be a type example of a non-volcanic rift. Key features of the conjugate margins are transition zones (TZs) that lie between clearly continental crust and presumed normal (Penrose-type) oceanic crust that appears up to 150–180 km farther seaward. Basement ridges drilled in the Iberia TZ consist of exhumed, serpentinized peridotite of continental affinity, consistent with seismic refraction studies. Although the boundaries between continental crust and the TZs can be defined with relative confidence, there are major questions about the position and nature of the change from rifting to normal sea-floor spreading at the seaward edges of the TZs. Notably, drilling of presumed oceanic crust in the young M-series anomalies ( To investigate and potentially resolve these conflicts, we analysed the tectonic history and deep (pre-Cenomanian) stratigraphy of the rift using seismic reflection profiles and drilling results. Rifting occurred in two main phases (Late Triassic–earliest Jurassic and Late Jurassic–Early Cretaceous). The first phase formed continental rift basins without significant thinning of continental crust. The second phase led to continental breakup, with extension concentrated in three episodes that culminated near the end of Berriasian, Hauterivian and Aptian time. The first two episodes appear to correlate with separation of continental crust in the southern and northern parts of the rift, respectively, suggesting that the rift opened from south to north in a two-step process. The third episode persisted through Barremian and Aptian time. We suggest that during this period there was continued exhumation of subcontinental mantle lithosphere at the plate boundary, and that elevated in-plane tensile stress throughout the rift caused intraplate extension, primarily within the exhumed mantle. This rifting may have been interrupted for a time during the Barremian when melt was introduced from the southern edge of the rift by plume magmatism that formed the Southeast Newfoundland Ridge and J Anomaly Ridge, and the conjugate Madeira–Tore Rise. We propose that the rising asthenosphere breached the subcontinental mantle lithosphere in latest Aptian–earliest Albian time, initiating sea-floor spreading. This resulted in relaxation of in-plane tensile stress (i.e. a pulse of relative compression) that caused internal plate deformation and enhanced mass wasting. This ‘Aptian event’ produced a strong, rift-wide reflection that is unconformably onlapped by post-rift sediments that were deposited as a stable sea-floor-spreading regime was established. Although previously considered to be a breakup unconformity associated with separation of continental crust, the event instead marks the final separation of the subcontinental mantle lithosphere. Our analysis indicates that interpretation of tectonic events in a non-volcanic rift must consider the rheology of the full thickness of the continental lithosphere, in addition to spatial and temporal changes in extension that may occur from segment to segment along the rift.