New discoveries of vertebrate remains from the Triassic of Riba de Santiuste,Guadalajara (Spain)     

Mélani Berrocal-Casero  Julia Audije-Gil  Rui Alexandre Castanhinha  Juan Alberto Pérez-Valera  Vanda Faria dos Santos  Manuel Segura 《Proceedings of the Geologists' Association. Geologists' Association》2018,129(4):526-541

The palaeontological sites of Riba de Santiuste and Sienes (Riba de Santiuste area) are located in the province of Guadalajara, Spain. They include a stratigraphic interval in Muschelkalk facies belonging to the “Cuesta del Castillo Sandstones” Formation and “Royuela Dolostones, Marls and Mudstones” Formation. These sites include numerous fossil plants, direct vertebrate remains, and vertebrate swim traces. The vertebrate remains correspond to a multitude of anatomical elements of Sauropterygia (Nothosauroidea, Placodontia) and possible Archosauria (Rauisuchia) remains. The fossil material attributed to nothosaurs includes teeth, coracoids, a thoracic vertebra, some isolated vertebral centra, humerus, rib fragments, and some dorsal and caudal vertebrae. The remains attributed to placodonts correspond to fragments of skull, quadrate, teeth and osteoderms. Other undetermined sauropterygian remains, such as ulnas, fragments of long bones, fragments of ribs, and articular facets of ribs have been also recovered. Additionally, a fragment of mandible and an intervertebral disk of indeterminate reptiles whose size could be compatible with archosaurs are also described. These bones are exceptionally well-preserved because the fossilization processes have preserved the microstructure of the tissues. The sites also show vertebrate traces, with parallel scratch impressions interpreted as swim traces. The relative stratigraphic position and the palaeontological content of these sites suggest a Ladinian age (Middle Triassic). The interpretation of the sedimentary facies here described also suggests that the sites could correspond to detrital-carbonate mixed deposits of coastal intertidal to supratidal environments.  相似文献   

Comparison of machine learning methods for copper ore grade estimation     

Bahram Jafrasteh  Nader Fathianpour  Alberto Suárez 《Computational Geosciences》2018,22(5):1371-1388

In this study, machine learning methods such as neural networks, random forests, and Gaussian processes are applied to the estimation of copper grade in a mineral deposit. The performance of these methods is compared to geostatistical techniques, such as ordinary kriging and indicator kriging. To ensure that these comparisons are realistic and relevant, the predictive accuracy is estimated on test instances located in drill holes that are different from the training data. The results of an extensive empirical study in the Sarcheshmeh porphyry copper deposit in Southeastern Iran illustrate that specially designed Gaussian processes with a symmetric standardization of the spatial location inputs and an anisotropic kernel yield the most accurate predictions. Furthermore, significant improvements are obtained when, besides location, information on the rock type is included in the set of predictor variables. This observation highlights the importance of carrying out detailed studies of the geological composition of the deposit to obtain more accurate ore grade predictions.  相似文献   

Water-table and discharge changes associated with the 2016–2017 seismic sequence in central Italy: hydrogeological data and a conceptual model for fractured carbonate aquifers     

Petitta  Marco  Mastrorillo  Lucia  Preziosi  Elisabetta  Banzato  Francesca  Barberio  Marino Domenico  Billi  Andrea  Cambi  Costanza  De Luca  Gaetano  Di Carlo  Giuseppe  Di Curzio  Diego  Di Salvo  Cristina  Nanni  Torquato  Palpacelli  Stefano  Rusi  Sergio  Saroli  Michele  Tallini  Marco  Tazioli  Alberto  Valigi  Daniela  Vivalda  Paola  Doglioni  Carlo 《Hydrogeology Journal》2018,26(4):1009-1026

A seismic sequence in central Italy from August 2016 to January 2017 affected groundwater dynamics in fractured carbonate aquifers. Changes in spring discharge, water-table position, and streamflow were recorded for several months following nine Mw 5.0–6.5 seismic events. Data from 22 measurement sites, located within 100 km of the epicentral zones, were analyzed. The intensity of the induced changes were correlated with seismic magnitude and distance to epicenters. The additional post-seismic discharge from rivers and springs was found to be higher than 9 m³/s, totaling more than 0.1 km³ of groundwater release over 6 months. This huge and unexpected contribution increased streamflow in narrow mountainous valleys to previously unmeasured peak values. Analogously to the L’Aquila 2009 post-earthquake phenomenon, these hydrogeological changes might reflect an increase of bulk hydraulic conductivity at the aquifer scale, which would increase hydraulic heads in the discharge zones and lower them in some recharge areas. The observed changes may also be partly due to other mechanisms, such as shaking and/or squeezing effects related to intense subsidence in the core of the affected area, where effects had maximum extent, or breaching of hydraulic barriers.

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Correction to: A Class-Kriging Predictor for Functional Compositions with Application to Particle-Size Curves in Heterogeneous Aquifers     

Alessandra Menafoglio  Piercesare Secchi  Alberto Guadagnini 《Mathematical Geosciences》2018,50(2):247-247

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Tsunami Early Warning Within Five Minutes     

Anthony Lomax  Alberto Michelini 《Pure and Applied Geophysics》2013,170(9-10):1385-1395

Tsunamis are most destructive at near to regional distances, arriving within 20–30 min after a causative earthquake; effective early warning at these distances requires notification within 15 min or less. The size and impact of a tsunami also depend on sea floor displacement, which is related to the length, L, width, W, mean slip, D, and depth, z, of the earthquake rupture. Currently, the primary seismic discriminant for tsunami potential is the centroid-moment tensor magnitude, M _w ^CMT , representing the product LWD and estimated via an indirect inversion procedure. However, the obtained M _w ^CMT and the implied LWD value vary with rupture depth, earth model, and other factors, and are only available 20–30 min or more after an earthquake. The use of more direct discriminants for tsunami potential could avoid these problems and aid in effective early warning, especially for near to regional distances. Previously, we presented a direct procedure for rapid assessment of earthquake tsunami potential using two, simple measurements on P-wave seismograms—the predominant period on velocity records, T _d , and the likelihood, T ₅₀ ^Ex , that the high-frequency, apparent rupture-duration, T ₀, exceeds 50–55 s. We have shown that T _d and T ₀ are related to the critical rupture parameters L, W, D, and z, and that either of the period–duration products T _d T ₀ or T _d T ₅₀ ^Ex gives more information on tsunami impact and size than M _w ^CMT , M _wp, and other currently used discriminants. These results imply that tsunami potential is not directly related to the product LWD from the “seismic” faulting model, as is assumed with the use of the M _w ^CMT discriminant. Instead, information on rupture length, L, and depth, z, as provided by T _d T ₀ or T _d T ₅₀ ^Ex , can constrain well the tsunami potential of an earthquake. We introduce here special treatment of the signal around the S arrival at close stations, a modified, real-time, M _wpd(RT) magnitude, and other procedures to enable early estimation of event parameters and tsunami discriminants. We show that with real-time data currently available in most regions of tsunami hazard, event locations, m _b and M _wp magnitudes, and the direct, period–duration discriminant, T _d T ₅₀ ^Ex can be determined within 5 min after an earthquake occurs, and T ₀, T _d T ₀, and M _wpd(RT) within approximately 10 min. This processing is implemented and running continuously in real-time within the Early-est earthquake monitor at INGV-Rome (http://early-est.rm.ingv.it). We also show that the difference m _b  ? log₁₀(T _d T ₀) forms a rapid discriminant for slow, tsunami earthquakes. The rapid availability of these measurements can aid in faster and more reliable tsunami early warning for near to regional distances.  相似文献   

Hydrogeological and geochemical characterisation of the Rock of Orvieto     

Alberto Tazioli  Pietro Conversini  Angelo Peccerillo 《Environmental Earth Sciences》2012,66(1):55-65

The town of Orvieto, located on the Rock of the same name, is an example of “vulnerable town”; problems of slope instability connected with the lithological and morphological characteristics of the Rock have been thoroughly examined and discussed during previous research studies. Hydrogeochemical data about groundwater recharging the springs present in the area were never taken into account. Pollution of the springs is well known but still occurs for unclear reasons. The aim of this work is therefore to present the results of a hydrogeological and geochemical investigation of all the springs along the slopes of Orvieto hill and at the foot of the tuffaceous Rock, to characterize the groundwater flow paths and to suggest a possible source of contamination. The research study was carried out during three hydrogeochemical surveys in the years 1998–1999, 2003–2004, and 2007–2008.  相似文献   

Solid phases controlling the mobility of potentially toxic elements and the generation of acid drainage in abandoned mine gold wastes from San Antonio–El Triunfo mining district,Baja California Sur,México     

Ernesto Hernández-Mendiola  Francisco Martín Romero  Margarita Gutiérrez-Ruiz  Carlos Alberto Magdaleno Rico 《Environmental Earth Sciences》2016,75(11):969

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A Class-Kriging Predictor for Functional Compositions with Application to Particle-Size Curves in Heterogeneous Aquifers     

Alessandra Menafoglio  Piercesare Secchi  Alberto Guadagnini 《Mathematical Geosciences》2016,48(4):463-485

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Activities permitted cartography: the integration of groundwater protection into land-use planning     

Alberto Jiménez-Madrid  Francisco Carrasco  Carlos Martínez 《Environmental Earth Sciences》2016,75(20):1372

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Alteration patterns of chromian spinels from La Cabaña peridotite,south-central Chile     

Fernando Barra  Fernando Gervilla  Elkin Hernández  Martin Reich  José Alberto Padrón-Navarta  José Maria González-Jiménez 《Mineralogy and Petrology》2014,108(6):819-836

La Cabaña peridotite is part of a dismembered ophiolite complex located within the metamorphic basement of the Coastal Cordillera of south-central Chile, and is the only location in Chile were Cr-spinels have been described so far. The La Cabaña peridotite is part of the Western Series unit, which comprises meta-sedimentary rocks, metabasites, and serpentinized ultramafic rocks. This unit has been affected by greenschist-facies metamorphism with reported peak PT conditions of 7.0–9.3 kbar and 380°–420 °C. Within La Cabaña peridotite Cr-spinels are present in two localities: Lavanderos and Centinela Bajo. In Lavanderos, Cr-spinel occurs in small chromitite pods and as accessory/disseminated grains with a porous or spongy texture in serpentinite, whereas in Centinela Bajo Cr-spinel is present as accessory zoned grains in partly serpentinized dunites, and in chromitite blocks. All Cr-spinels display variable degrees of alteration to Fe²⁺-rich chromite with a variation trend of major elements from chromite to Fe²⁺-rich chromite similar to those observed in other locations, i.e., an increase in Fe₂O₃ and FeO, a decrease in Al₂O₃ and MgO. Cr₂O₃ content increases from chromite to Fe²⁺-rich chromite in chromitite pods from Lavanderos and chromitite blocks from Centinela Bajo, but decreases in ferrian chromite zones in accessory grains from Centinela Bajo. The minor element (Ti, V, Zn, Ni) content is mostly low and does not exceed 0.4 wt.%, with the exception of MnO (<0.9 wt.%), which shows a correspondence with increasing degree of alteration. Cr# (Cr/Cr?+?Al) versus Mg# (Mg/Mg?+?Fe²⁺) and Fe³⁺/Fe³⁺+Fe²⁺ versus Mg# plots are used to illustrate the Cr-spinel alteration process. Overall, the Cr-spinels from Lavanderos (chromitite pods and disseminated grains) exhibit Cr# values ranging from 0.6 to 1.0, Mg# (Mg/Mg?+?Fe²⁺) below 0.5, and (Fe³⁺/Fe³⁺+Fe²⁺) <0.4. Cr-spinels from chromitites in Centinela Bajo have Cr# and Mg# values that range from 0.65 to 1.0, and 0.7-0.3, respectively, and (Fe³⁺/Fe³⁺+Fe²⁺)?3+/Fe³⁺+Fe²⁺) ratio is less than 0.4 in chromite cores and Fe²⁺-rich chromite, and >0.5 in ferrian chromite and Cr-magnetite. Interpretation of the data obtained and Cr-spinel textures indicate that the alteration of Cr-spinel is a progressive process that involves in its initial stages the reaction of chromite with olivine under water-saturated conditions to produce clinochlore and Fe²⁺-rich chromite. During this stage the chromite can also incorporate Ni, Mn, and/or Zn from the serpentinization fluids. As alteration progresses, Fe²⁺-rich chromite loses mass resulting in the development of a spongy texture. In a later stage and under more oxidizing conditions Fe³⁺ is incorporated in chromite/Fe²⁺-rich chromite shifting its composition to an Fe³⁺-rich chromite (i.e., ferrian chromite). Depending on the fluid/rock and Cr-spinel/silicate ratios, Cr-magnetite can also form over Fe²⁺-rich chromite and/or ferrian chromite as a secondary overgrowth. The compositional changes observed in Cr-spinels from La Cabaña reflect the initial stages of alteration under serpentinization conditions. Results from this study show that the alteration of Cr-spinels is dependent on temperature. The degree and extent of alteration (formation of Fe²⁺-rich and/or ferrian chromite) are controlled by the redox nature of the fluids, the Cr-spinel/silicate and the fluid/rock ratios.  相似文献