Browsing Earth Science by Title
Now showing items 63-82 of 121
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Large-Amplitude Variations in Carbon Cycling and Terrestrial Weathering during the Latest Paleocene and Earliest Eocene: The Record at Mead Stream, New Zealand
(2012)The late Paleocene to early Eocene was marked by major changes in Earth surface temperature and carbon cycling. This included at least two, and probably more, geologically brief (<200-k.yr.) intervals of extreme warming, ... -
Large-scale tectonic cycles in Europe revealed by distinct Pb isotope provinces
(2016)Lead isotopic systematics of U-poor minerals, such as sulfides and feldspars, can provide unique insights into the origin and evolution of continents because these minerals “freeze in” the Pb isotopic composition of the ... -
Late Holocene climate change recorded in proxy records from a Bransfield Basin sediment core, Antarctic Peninsula
(2014)The glacimarine environment of the Antarctic Peninsula region is one of the fastest warming places on Earth today, but details of changes in the recent past remain unknown. Large distances and widespread variability separate ... -
Lg attenuation in northeast China using NECESSArray data
(2015)The 127 station NorthEast China Extended SeiSmic Array (NECESSArray) provides large quantities of high quality seismic data in northeast China that allow us to resolve lateral variations of Lg Q or crustal attenuation at ... -
Lithosphere versus asthenosphere mantle sources at the Big Pine Volcanic Field, California
(2012)[1] Here we report the first measurements of the H2O content of magmas and mantle xenoliths from the Big Pine Volcanic Field (BPVF), California, in order to constrain the melting process in the mantle, and the role of ... -
Lithospheric expression of cenozoic subduction, mesozoic rifting and the Precambrian Shield in Venezuela
(2015)We have combined surface wave tomography with Ps and Sp receiver-function images based on common-conversion-point (CCP) stacking to study the upper mantle velocity structure, particularly the lithosphere–asthenosphere ... -
Lithospheric structure of Iberia and Morocco using finite-frequency Rayleigh wave tomography from earthquakes and seismic ambient noise
(2017)We present a new 3-D shear velocity model of the western Mediterranean from the Pyrenees, Spain, to the Atlas Mountains, Morocco, and the estimated crustal and lithospheric thickness. The velocity model shows different ... -
Low wave speed zones in the crust beneath SE Tibet revealed by ambient noise adjoint tomography
(2014)We present a refined 3D crustal model beneath SE Tibet from ambient noise adjoint tomography. Different from ray-theory-based tomography, adjoint tomography in this study incorporates a spectral-element method (SEM) and ... -
Magma flow between summit and Pu‘u ‘ Ō ‘ō at Kīlauea Volcano, Hawai‘i
(2013)[1] Volcanic eruptions are often accompanied by spatiotemporal migration of ground deformation, a consequence of pressure changes within magma reservoirs and pathways. We modeled the propagation of pressure variations ... -
Magmatic recharge in continental flood basalts: Insights from the Chifeng igneous province in Inner Mongolia
(2015)Eruptive sequences can be used as windows into the thermal and chemical evolution of magma chambers. We examined a continuous vertical section of the Baichahe basalt flow associated with the late Cenozoic Chifeng flood ... -
The Malpelo Plate Hypothesis and implications for nonclosure of the Cocos-Nazca-Pacific plate motion circuit
(2017)Using global multiresolution topography, we estimate new transform-fault azimuths along the Cocos-Nazca plate boundary and show that the direction of relative plate motion is 3.3° ± 1.8° (95% confidence limits) clockwise ... -
Mantle-driven uplift of Hangai Dome: New seismic constraints from adjoint tomography
(2015)The origin of Hangai Dome, an unusual large-scale, high-elevation low-relief landform in central Mongolia, remains enigmatic partly due to lack of constraints on its underlying seismic structure. Using adjoint tomography—a ... -
Measurement of Rayleigh wave ellipticity and its application to the joint inversion of high-resolutionﾠSwave velocity structure beneath northeast China
(2016)We present a new 3-D S wave velocity model of the northeast (NE) China from the joint inversion of the Rayleigh wave ellipticity and phase velocity at 8–40 s periods. Rayleigh wave ellipticity, or Rayleigh wave Z/H (vertical ... -
Midinfrared third-harmonic generation from macroscopically aligned ultralong single-wall carbon nanotubes
(2013)We report the observation of strong third-harmonic generation from a macroscopic array of aligned ultralong single-wall carbon nanotubes (SWCNTs)with intensemidinfrared radiation. Through power-dependent experiments, we ... -
Missing Lead and High 3He/4He in Ancient Sulfides Associated with Continental Crust Formation
(2014)Major terrestrial reservoirs have Pb isotopes more radiogenic than the bulk silicate Earth. This requires a missing unradiogenic Pb reservoir, which has been argued to reside in the lower continental crust or dissolved in ... -
Modeling flow and sediment transport dynamics in the lowermost Mississippi River, Louisiana, USA, with an upstream alluvial-bedrock transition and a downstream bedrock-alluvial transition: Implications for land building using engineered diversions
(2015)The lowermost Mississippi River, defined herein as the river segment downstream of the Old River Control Structure and hydrodynamically influenced by the Gulf of Mexico, extends for approximately 500?km. This segment ... -
Modern rates of glacial sediment accumulation along a 15° S-N transect in fjords from the Antarctic Peninsula to southern Chile
(2013)[1] Rates of glacial erosion in temperate climates rank among the highest worldwide, and the sedimentary products of such erosion record climatic and tectonic signals in many glaciated settings, as well as temporal changes ... -
Multiparameter adjoint tomography of the crust and upper mantle beneath East Asia: 1. Model construction and comparisons
(2015)We present a 3-D radially anisotropic model of the crust and mantle beneath East Asia down to 900 km depth. Adjoint tomography based on a spectral element method is applied to a phenomenal data set comprising 1.7 million ... -
NanoSIMS results from olivine-hosted melt embayments: Magma ascent rate during explosive basaltic eruptions
(2014)The explosivity of volcanic eruptions is governed in part by the rate at which magma ascends and degasses. Because the time scales of eruptive processes can be exceptionally fast relative to standard geochronometers, magma ... -
A new bubble dynamics model to study bubble growth, deformation, and coalescence
(2014)We propose a new bubble dynamics model to study the evolution of a suspension of bubbles over a wide range of vesicularity, and that accounts for hydrodynamical interactions between bubbles while they grow, deform under ...
