Search results for "boundary"

Pressure solution compaction of sodium chlorate and implications for pressure solution in NaCl

1999

Sodium chloride (NaCl) has been extensively used as a material to develop, test and improve pressure solution (PS) rock deformation models. However, unlike silicate and carbonate rocks, NaCl can deform plastically at very low stresses (0.5 MPa). This could mean that NaCl is less suitable for use as an analogue for rocks that do not deform plastically at conditions where PS is important. In order to test the reliability of NaCl as a rock analogue, we carried out a series of uniaxial compaction experiments on sodium chlorate (NaClO3) at room pressure and temperature (P‐T) conditions and applied effective stresses of 2.4 and 5.0 Mpa. NaClO3 is a very soluble, elastic‐brittle salt, that cannot …

Domain boundary migration at multiple scales in experiment and nature

2000

Quantification of the microstructural evolution of polycrystalline fabrics using FAME: Application to in situ deformation of ice

2014

Abstract In geology, glaciology and material science new technological advances result in an ever increasing amount of data and datasets, in particular when in situ experiments are conducted. Rapid, rigorous and reliable statistical treatment is needed to allow researchers to access these large datasets for further analysis. Here, we present FAME (Fabric Analyser based Microstructure Evaluation), a suite of Matlab® scripts that utilize the Matlab® open-source toolboxes MTEX and PolyLX (optional) for rapid quantification of thin section data. The data has been collected using an automated Fabric Analyser at a spatial resolution of 5 μm/pixel. From the dataset, grain maps are reconstructed an…

Integrated stratigraphy of the Oligocene pelagic sequence in the Umbria- Marche basin (north-eastern Apennines, Italy): A potential Global Stratotype…

2008

The Oligocene represents an important time period from a wide range of perspectives and includes signifi cant climatic and eustatic variations. The pelagic succession of the Umbria-Marche Apennines (central Italy) includes a complete and continuous sequence of marly limestones and marls, with volcaniclastic layers that enable us to construct an integrated stratigraphic framework for this time period. We present here a synthesis of detailed biostratigraphic, magnetostratigraphic, and hemostratigraphic studies, along with geochronologic results from several biotite-rich volcaniclastic layers, which provide the means for an accurate and precise radiometric calibration of the Oligocene time sca…

The Global Stratotype Section and Point (GSSP) of the Serravallian Stage (Middle Miocene)

2009

The Global Stratotype Section and Point (GSSP) for the Base of the Serravallian Stage (Middle Miocene) is defined in the Ras il Pellegrin section located in the coastal cliffs along the Fomm Ir-Rih Bay on the west coast of Malta (35°54'50"N, 14°20'10"E). The GSSP is at the base of the Blue Clay Formation (i.e., top of the transitional bed of the uppermost Globigerina Limestone). This boundary between the Langhian and Serravallian stages coincides with the end of the major Mi-3b global cooling step in the oxygen isotopes and reflects a major increase in Antarctic ice volume, marking the end of the Middle Miocene climate transition and the Earth's transformation into an "Icehouse" climate sta…

Conodont association of the Bashkirian-Moscovian boundary interval of the Donets Basin, Ukraine

2018

Ten sections spanning the Bashkirian-Moscovian boundary interval were studied in the Donets Basin. Six of them contain most representative conodont and foraminifer associations. In this paper we focused on three the most complete sections that include stratigraphically important conodont species, which belong to the Declinognathodus, Idiognathoides, Idiognathodus, Neognathodus, “Streptognathodus”, Mesogondolella and Diplognathodus genera. The majority of those species are widely distributed, which makes the correlation to other areas reliable. Two biotic events in conodont evolution were discovered in these sections. Two conodont lineages established here are considered as potential markers…

‘‘Distinguishing eustatic and epeirogenic controls on Lower-Middle Cambrian boundary successions in West Gondwana (Morocco and Iberia)’’, by Ed Landi…

2008

A sub-supersolution approach for Neumann boundary value problems with gradient dependence

2020

Abstract Existence and location of solutions to a Neumann problem driven by an nonhomogeneous differential operator and with gradient dependence are established developing a non-variational approach based on an adequate method of sub-supersolution. The abstract theorem is applied to prove the existence of finitely many positive solutions or even infinitely many positive solutions for a class of Neumann problems.

Unified thermodynamic framework for nonlocal/gradient continuum theories

2003

Abstract A thermodynamic framework, equipped with the concept of nonlocality (energy) residual, is utilized to address nonlocal/gradient internal variable material models. A unified procedure is provided for either nonlocal and gradient materials, which makes it possible to determine the thermodynamic restrictions upon the constitutive equations, and in particular the pertinent state equations, the consistent form of the dissipation power and the constitutive expression of the nonlocality residual. Additionally, for gradient models, the associated nonstandard boundary conditions are derived, pointing out their basically constitutive nature and their substantial differences from the standard…

Modeling of anisotropic grain growth in minerals

2001

The role of surface energy anisotropy during grain growth is investigated using both physical experiments on octachloropropane and numerical experiments using the Elle microstructural modelling system. In particular the effects of anisotropy on growth rates, grain shapes and lattice preferred orientations are analysed. Anisotropic growth in thin polycrystalline sheets of octachloropropane is found to systematically remove certain c-axis orientations from the sample, without obviously modifying the grain shapes. By comparison with equivalent numerical experiments, we can explain these observations with a simple boundary layer model that treats each side of each grain boundary as an independe…