Microimaging spectroscopy and scanning electron microscopy of Northwest Africa 8657 shergottite: Interpretation of future in situ Martian data

Microimaging spectroscopy is going to be the new frontier for validating reflectance remote sensed data from missions to solar system bodies. In this field, microimaging spectroscopy of Martian meteorites can provide important and new contributions to interpret data that will be collected by next instruments onboard rover missions to Mars, such as for example Exomars‐2020/Ma_MISS spectrometer. In this paper, a slab from the Northwest Africa (NWA) 8657 shergottite was studied using the SPectral IMager (SPIM) microimaging spectrometer, in the visible‐infrared (VIS‐IR) range, with the aim to subsequently validate the spectral data by means of different independent techniques. The validation was thus carried out, for the first time, comparing SPIM spectral images, characterized by high spatial and spectral resolution, with mineralogical–petrological analyses, obtained by scanning electron microscopy (SEM). The suitability of the SPIM resolution to detect and map augite, pigeonite, maskelynite, and other minor phases as calcite, Ca‐phosphates, and troilite/pyrrhotite with no loss of information about mineral distribution on the slab surface, was ascertained. The good agreement found between spectral and mineralogical data suggests that spectral‐petrography of meteorites may be useful to support in situ investigations on Martian rocks carried out by MaMiss spectrometer during Exomars2020 mission. Moreover, micro spectral images could be also useful to characterize, in a nondestructive way, Martian meteorites and other rare minerals occurring in meteorites. The results obtained in this work represent not only a methodological contribution to the study of meteorites but furnish also elements to reconstruct the history of this sample. The finding of zoned pyroxene, symplectitic texture, amorphous phases as maskelynite, and Fe‐merrillite permits us to hypothesize four stages, i.e., (1) igneous formation of rimmed pyroxenes and other minerals, (2) retrograde metamorphism, (3) shock by impact, and (4) secondary minerals by terrestrial contamination.     

Instrument Calibration of the <Emphasis Type="Italic">Interface Region Imaging Spectrograph</Emphasis> (IRIS) Mission

The Interface Region Imaging Spectrograph (IRIS) is a NASA small explorer mission that provides high-resolution spectra and images of the Sun in the 133?–?141 nm and 278?–?283 nm wavelength bands. The IRIS data are archived in calibrated form and made available to the public within seven days of observing. The calibrations applied to the data include dark correction, scattered light and background correction, flat fielding, geometric distortion correction, and wavelength calibration. In addition, the IRIS team has calibrated the IRIS absolute throughput as a function of wavelength and has been tracking throughput changes over the course of the mission. As a resource for the IRIS data user, this article describes the details of these calibrations as they have evolved over the first few years of the mission. References to online documentation provide access to additional information and future updates.     

Sampling Density in Regional Exploration and Environmental Geochemical Studies: A Review

Natural Resources Research - A variety of factors contribute to the proper and efficient evaluation of geochemical programs including sampling medium, sample size and sample fraction, sampling...     

Artificial Fracture Stimulation of Rock Subjected to Large Isotropic Confining Stresses in Saline Environments: Application in Deep-Sea Gas Hydrate Recovery

Natural Resources Research - The low permeability of gas hydrate deposits leads to poor extraction rates. Artificial fracture stimulation could significantly improve the recovery rate of an...     

Yielding seismic response of code-designed single-storey asymmetric structures

A study on the seismic performance of asymmetric structures with non-linear behaviour and random properties is presented. The structural response of single-storey models, designed using different code criteria is studied using both a deterministic and a probabilistic approach. The worst structural behaviour, in terms of ductility demands, is obtained for symmetric models considering uncertain properties. It is shown that an arbitrary increase of the total lateral strength of the structures does not lead to an increment of the structural safety proportional to the total lateral strength increase, implying that an expensive structure is not always the safest. © 1998 John Wiley & Sons, Ltd.     

黄渤海近海海藻养殖规模及固碳强度时空分布

定量研究黄渤海近海大型经济海藻的面积、产量及其固碳能力和空间分布,对海洋牧场建设和海藻固碳强度研究具有重要意义。基于2001—2016年《中国渔业统计年鉴》和2016年《山东渔业统计年鉴》数据,对2001—2015年黄渤海近海和全国近海养殖大型经济海藻的产量、面积及结构进行了对比分析,采用CCI指数计算了黄渤海近海及全国近海大型经济海藻的固碳能力,并分析了2016年山东省养殖海藻的空间分布特征。研究表明:2001—2015年海藻养殖面积、产量整体呈上升趋势,其中全国海藻养殖面积在2005—2007年,产量在2006—2007年出现间断性下降,黄渤海海藻养殖面积在2005—2007年,产量在2001—2003年、2005—2008年出现阶段性下降;黄渤海近海海藻养殖产量占全国近海海藻养殖产量年均约45.53%,固碳总量占全国海藻固碳总量年均约51.75%,其中裙带菜,海带及紫菜为黄渤海海藻养殖的主要经济藻类;以山东省为典型省份的海藻固碳强度在海岸带间表现出明显的空间分布差异,其中威海市荣成区域人工养殖海藻固碳总量最多。     

A model for pore‐fluid‐sensitive rock behavior using a weathering state parameter

Chalk and other porous rocks are known to behave differently when saturated with different pore fluids. The behavior of these rocks varies with different pore fluids and additional deformation occurs when the pore fluid composition changes. In this article, we review the evidence that behavior in porous rocks is pore‐fluid‐dependent, present a constitutive model for pore‐fluid‐dependent porous rocks, and present a compilation of previously published data to develop quantitative relationships between various pore fluids and mechanical behavior. The model proposed here is based on a state parameter approach for weathering and has similarities to models previously proposed for weathering‐sensitive rocks in that the values for parameters that characterize material behavior vary as a function of weathering. Comparisons with published experimental data indicate that the model is capable of reproducing observed behavior of chalk under a variety of loading conditions and changes in pore fluid composition. Copyright © 2008 John Wiley & Sons, Ltd.