Northwest Africa 6232: Visible–near infrared reflectance spectra variability of an olivine diogenite

Visible and near-infrared (VNIR) reflectance is an important spectroscopic technique to identify minerals, and their associations, on planetary body surfaces. Howardites, eucrites, and diogenites (HED) are a class of igneous-like meteorites whose genetic connection with asteroid 4 Vesta has since long been inferred and recently confirmed by Dawn mission results. Pyroxene and olivine are the two major mafic minerals present in HED which can be identified with VNIR reflectance measurements. Thus, studying the compositional variability of those phases and their mixtures by means of laboratory spectroscopic measurements on different diogenitic or eucritic samples is one of the prime methods to better understand the evolution of 4 Vesta's crust. Here, we report the VNIR reflectance spectral analysis of a harzburgitic olivine diogenite, Northwest Africa 6232 (probably paired with Northwest Africa 5480), containing variable amounts of olivine as small grains or aggregates. We found that the olivine diogenite spectral parameters (e.g., band position) of powdered samples and polished slabs are in agreement. Moreover, the olivine diogenite band position shifts from synthetic orthopyroxene in accordance with the presence of olivine and chromite. In particular, the presence of a large olivine clast permits us to determine a linear variation of the band position from synthetic orthopyroxene and olivine, but underestimates the presence of olivine in the olivine diogenite spot.     

A detailed mineralogical,petrographic, and geochemical study of the highly reduced chondrite,Acfer 370

Among the many ungrouped meteorites, Acfer 370, NWA 7135, and El Médano 301—probably along with the chondritic inclusion in Cumberland Falls and ALHA 78113—represent a homogeneous grouplet of strongly reduced forsterite‐rich chondrites characterized by common textural, chemical, mineralogical, and isotopic features. All of these meteorites are much more reduced than OCs, with a low iron content in olivine and low‐Ca pyroxene. In particular, Acfer 370 is a type 4 chondrite that has olivine and low‐Ca pyroxene compositional ranges of Fa 5.2–5.8 and Fs 9.4–33.4, respectively. The dominant phase is low‐Ca pyroxene (36.3 vol%), followed by Fe‐Ni metal (16.3 vol%) and olivine (15.5 vol%); nevertheless, considering the Fe‐oxyhydroxide (due to terrestrial weathering), the original metal content was around 29.6 vol%. Finally, the mean oxygen isotopic composition Δ¹⁷O = +0.68‰ along with the occurrence of a silica phase, troilite, Ni‐rich phosphides, chromite, and oldhamite confirms that these ungrouped meteorites have been affected by strong reduction and are different from any other group recognized so far.     

Relation water content ratio-to-liquidity index versus the Atterberg limits ratio evaluated with the Kaniadakis exponential law

Water content ratio (WCR) is defined as the ratio water content to liquid limit (LL) and it is proved to be a good replacer of the well-known parameter liquidity index (LI) to predict shear strength of fine-grained soils. An interesting correlation between the slope of LI and WCR and LL/PL ratio was observed. However, this trend is poorly described by conventional regression functions. By employing the Kaniadakis exponential law based on the relativistic mechanics, 22 data set, considering the LL/PL vs the slope of LI and WCR, were very-well matched.     

The morphology of a Messinian valley and its hinterland (Ventimiglia,NW Italy): a Miocene to Pliocene reconstruction

Along the Ligurian coast (NW Italy), Alpine‐folded and slightly metamorphosed rocks experienced fluvial to marine erosion prior to and during the base level fall associated with the Messinian salinity crisis. Following the subsequent sea‐level rise at the onset of the Pliocene, valleys incised along the coastal margins during the Messinian salinity crisis were partly filled with Pliocene marine and continental deposits. One such valley‐infill system is exposed near Ventimiglia (NW Italy). Using geological cross‐sections and geomorphological analysis we have constrained its shape and dimensions, as well as the morphology of its hinterland. The Messinian valley was very open, ∼10 km wide and probably 500 m deep. The basal unconformity between the Pliocene sediments and the underlying substratum is characterized by a smooth surface that has on either side of the palaeo‐valley a dip between 2 and 10°. The basal unconformity in the southernmost part of the palaeo‐valley roughly coincides with present‐day sea level. The hinterland of the middle Pliocene sea was characterized by kilometres‐wide valleys surrounded by mountains with a relief gentler than at present. The shapes and dimensions of the Messinian Ventimiglia valley and the relief during Pliocene times are different from those derived from comparable structures in SE France and NW Italy. We interpret this as being due to the exhumation history that the Ventimiglia region, different from the surrounding areas, experienced over the last few million years. Copyright © 2006 John Wiley & Sons, Ltd.     

The 1895 Ljubljana earthquake: can the intensity data points discriminate which one of the nearby faults was the causative one?

The earthquake (Mw 6 from the SHEEC defined by the MDPs) that occurred in the central part of Slovenia on 14 April, 1895, affected a broad region, causing deaths, injuries, and destruction. This event was much studied but not fully explained; in particular, its causative source model is still debated. The aim of this work is to contribute to the identification of the seismogenic source of this destructive event, calculating peak ground velocity values through the use of different ground motion prediction equations (GMPEs) and computing a series of ground motion scenarios based on the result of an inversion work proposed by Juki? in 2009 and on various fault models in the surroundings of Ljubljana: Vi?, ?elimlje, Borovnica, Vodice, Ortnek, Mi?jedolski, and Dobrepolje faults. The synthetic seismograms, at the basis of our computations, are calculated using the multi-modal summation technique and a kinematic approach for extended sources, with a maximum peak ground velocity value of 1 Hz. The qualitative and quantitative comparison of these simulations with the macroseismic intensity database allows us to discriminate between various sources and configurations. The quantitative validation of the seismic source is done using ad hoc ground motion to intensity conversion equations (GMICEs), expressly calculated for this study. This study allows us to identify the most probable causative source model of this event, contributing to the improvement of the seismotectonic knowledge of this region. The candidate fault that has the lowest values of average differences between observed and calculated intensities and chi-squared is a strike slip fault with a toward-north rupture as the Ortnek fault.     

Multi-frequency Electromagnetic Induction Survey for Archaeological Prospection: Approach and Results in Han Hangu Pass and Xishan Yang in China

This study presents the potential of multi-frequency electromagnetic induction (EMI) in archaeology. EMI is currently less employed for archaeological prospection with respect to other geophysical techniques. It is capable of identifying shallow subsurface relics by simultaneously measuring the apparent electrical conductivity (EC_a) and apparent magnetic susceptibility (MS_a). Moreover, frequency sounding is able to quantify the depths and vertical shapes of buried structures. In this study, EMI surveys with five frequencies were performed at two heritage sites with different geological conditions: Han Hangu Pass characterized by cinnamon soil and Xishan Yang by sandy loams. In the first site, high EC_a values were observed with variations in depth correlated to archaeological remains. Moreover, electromagnetic anomalies related to an ancient road and five kiln caves were identified. In the second site, an ancient tomb, indicating extremely low EC_a and high MS_a, was discovered. Its electromagnetic properties are attributed to the cavity and ferroferric oxides.     

Improvement of Ground Penetrating Radar (GPR) Data Interpretability by an Enhanced Inverse Scattering Strategy

This paper is inserted into the framework of inverse scattering with application to Ground Penetrating Radar (GPR) data and is meant to provide a method helping to apply inverse scattering algorithms to electrically large investigation domains. In particular, we focus on the depth slices that are particularly important in application on cultural heritage and propose in relationship with the depth slices a strategy that we will call “shifting zoom” that is specifically a method to mitigate the effects of the limited view angle in the linear tomographic inversion applied to GPR data. In particular, this paper is an extended version of the contribution (Persico et al. in: Proceedings of Imeko international conference on metrology for archaeology and cultural heritage, Lecce, Italy, 2017a), published in the Proceedings of the conference metrology for archaeology 2017. We propose here a validation of the shifting zoom versus experimental data gathered in a controlled test site, and we will show the effect of the shifting zoom on depth slices achieved from these data after a linear inverse scattering processing has been applied for their focusing.