Geologica Acta最新文献

{"title":"Insights into the structural evolution of the pre-Variscan rocks of the Eastern Pyrenees from La Molina quartz veins; constraints on chlorite and fluid inclusion thermometry","authors":"Eloy González-Esvertit, À. Canals, J. Casas, F. Nieto","doi":"10.1344/geologicaacta2020.18.18","DOIUrl":"https://doi.org/10.1344/geologicaacta2020.18.18","url":null,"abstract":"Quartz veins hosted in the infra and overlying series to the (Sardic) Upper Ordovician Unconformity provide new insights into the structural and thermal evolution of the pre-Variscan rocks of the Eastern Pyrenees. In the La Molina area (Canigó massif), two generations of metric quartz veins (V1 and V2) are distinguished by their distribution patterns and their relationships to the deformational macro, meso, and microstructures. P-T formation conditions are obtained by combining chlorite geothermometry and fluid inclusion microthermometry data. Discrepancy on formation temperature for chlorites located at different positions within the veins are discussed, concluding that veins grew in a low fluid/rock ratio regime. V1 veins can be related to the Late Ordovician syn-sedimentary faulting episode as revealed by their distribution patterns, formation mechanisms, and fluid-rock interactions. We propose an Alpine age for the V2 veins, based on their structure and the emplacement conditions of 318 ± 12°C and 2.4 ± 0.2kbar, with an estimated geothermal gradient of 34°C∙km-1 and a burial depth of ca. 9km. Results obtained here are compared with other quartz veins spread throughout the Paleozoic basement of the Eastern Pyrenees.","PeriodicalId":55107,"journal":{"name":"Geologica Acta","volume":" ","pages":""},"PeriodicalIF":1.5,"publicationDate":"2020-11-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41831572","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Time lag between metamorphism and crystallization of anatectic granites (Córdoba, Argentina)","authors":"F. D. 'Eramo, J. J. Estéban, M. Demartis, E. Aragón, J. Coniglio, L. Pinotti","doi":"10.1344/geologicaacta2020.18.17","DOIUrl":"https://doi.org/10.1344/geologicaacta2020.18.17","url":null,"abstract":"SHRIMP and LA-ICP-MS analyses carried out on zircons from the Río de los Sauces granite revealed their metamorphic and igneous nature. The metamorphic zircons yielded an age of 537±4.8 (2σ)Ma that probably predates the onset of the anatexis during the Pampean orogeny. By contrast, the igneous zircons yielded a younger age of 529±6 (2σ)Ma and reflected its crystallization age. These data point to a short time lag of ca. 8Myr between the High Temperature (HT) metamorphic peak and the subsequent crystallization age of the granite. Concordia age of 534±3.8 (2σ)Ma, for both types of zircon populations, can be considered as the mean age of the Pampean HT metamorphism in the Sierras de Córdoba.","PeriodicalId":55107,"journal":{"name":"Geologica Acta","volume":" ","pages":""},"PeriodicalIF":1.5,"publicationDate":"2020-11-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43700397","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Age of the basement beneath the Mesozoic Lusitanian Basin revealed by granitic xenoliths from the Papôa volcanic breccia (West Iberia)","authors":"M. F. Pereira, C. Gama, José Silva, Í. D. D. Silva","doi":"10.1344/geologicaacta2020.18.16","DOIUrl":"https://doi.org/10.1344/geologicaacta2020.18.16","url":null,"abstract":"The dyke of the Papoa volcanic breccia cross-cutting the Lower Jurassic sequence of the Lusitanian Basin (West Iberia) contains granitic xenoliths. In this study, for the first time, U-Th-Pb zircon analysis of two xenoliths yielded 298 ± 4 Ma for biotite granite and of 292 ± 2 Ma for two-mica granite, indicating that the pre-Mesozoic basement of the Lusitanian Basin includes Permian intrusions. These ages are close within the margin of error of the age of the Late Carboniferous granites of the Berlengas isle that with the Late Devonian high-grade metamorphic rocks of the Farilhoes isles, located northwest of the study area, which form the pre-Mesozoic basement of the Lusitanian Basin. These new geochronological findings enable it to be established that Permo-Carboniferous magmatism lasted at least 13 Ma, in this region of the Appalachian-Variscan belt. Furthermore, a comparison with available data from Paleozoic tectonic units of the Appalachian-Variscan belt located both in the Iberian Massif and outside it enables the suggestion to be made that the Lusitanian Basin (Peniche) most probably rests on the South Portuguese Zone, which may also be correlated with the Rhenohercynian Zone present in southwest England, and the Meguma terrane of Nova Scotia.","PeriodicalId":55107,"journal":{"name":"Geologica Acta","volume":"18 1","pages":"1-14"},"PeriodicalIF":1.5,"publicationDate":"2020-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47947282","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Source rock and shale oil potential of the Pabdeh Formation (Middle–Late Eocene) in the Dezful Embayment, southwest Iran","authors":"B. Alizadeh, A. Opera, M. Kalani, M. Alipour","doi":"10.1344/geologicaacta2020.18.15","DOIUrl":"https://doi.org/10.1344/geologicaacta2020.18.15","url":null,"abstract":"The Pabdeh Brown Shale Unit (BSU) is an organic-rich calcareous mudstone within the Paleogene Pabdeh Formation, which has not yet been investigated in detail. A total of 166 core and cutting samples were selected from four wells in the Dezful Embayment to investigate the organic geochemical and the mineralogical compositions, as well as the shale oil potential of the BSU. XRD results show that it is mainly comprised of calcite (53wt.%), clay minerals (25wt.%), and quartz (14wt.%). TOC contents generally range from 1 to 9wt.% (avg. 4.2, 2.9, 5.2 and 3.3wt.%, for GS, KR, RR and RS wells, respectively) with HI values ranging between 400 and 650 mg HC/g TOC. Based on average values of T max and vitrinite reflectance, as well as saturate biomarker ratios, the BSU is immature at wells RR and RS (ranging from 0.3 to 0.53%) and its maturity increases northward at wells KR and GS (ranging from 0.5% to 0.67%). The organic matter is dominated by Type ΙΙ kerogen and is generally composed of liptinite and amorphous material with minor terrestrial input. Based on various biomarker parameters, the organic matter was most likely deposited under anoxic marine conditions. The mineralogical characteristics ( i.e. presence of brittle minerals) and organic geochemical properties ( i.e . TOC >2wt% and Type II kerogen) support the conclusion that the Pabdeh BSU displays a considerable shale oil potential where it attains appropriate thermal maturity.","PeriodicalId":55107,"journal":{"name":"Geologica Acta","volume":"18 1","pages":"1-22"},"PeriodicalIF":1.5,"publicationDate":"2020-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47125364","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Foraminifera of shallow and very shallow facies from the upper Eocene–lower Oligocene Kazandere Member, Soğucak Formation, Thrace Basin, northwest Turkey","authors":"E. Sirel, T. Ayyıldız, A. Deveciler","doi":"10.1344/GEOLOGICAACTA2020.18.14","DOIUrl":"https://doi.org/10.1344/GEOLOGICAACTA2020.18.14","url":null,"abstract":"The middle−upper Eocene to lower Oligocene Kazandere Limestone Member of the Sogucak Formation is widely represented in the Thrace Basin and rich in shallow-water marine foraminifera. Very shallow-water Priabonian facies described here include Borelis vonderschimitti, Borelis laxispira sp. nov., Chapmanina gassinensis, Chapmanina elongate sp. nov., Pfendericonusglobulus sp. nov., Orbitolites minimus,Coscinospira sp. Last occurrences of the aforementioned Priabonian species and first appearances of the shallow-water marine Rupelian species Nummulites fichteli, Nummulites vascus and Operculina complanata define the Eocene−Oligocene boundary in the new Kazandere Member at the northeast Thrace Basin.","PeriodicalId":55107,"journal":{"name":"Geologica Acta","volume":"18 1","pages":"1-21"},"PeriodicalIF":1.5,"publicationDate":"2020-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48133276","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The building stone of the Roman city of Lixus (NW Morocco): provenance, petrography and petrophysical characterization","authors":"T. Ajanaf, D. G. Grás, A. Navarro, J. Martín‐Martín, Joan Ramon Rosell, A. Maate","doi":"10.1344/geologicaacta2020.18.13","DOIUrl":"https://doi.org/10.1344/geologicaacta2020.18.13","url":null,"abstract":"The characterization of building materials is a key tool to assess deterioration processes and improve potential restoration works of archaeological sites. The aim of this paper is to identify and characterize the most important building stones used in the construction of the Roman city of Lixus (Larache, Morocco) by means of petrographic and petrophysical techniques. Based on the visual analysis of the monuments, three major building stones (i.e. lithotypes) have been identified: i) Oligocene sandstones, ii) Quaternary sandstones and iii) Quaternary conglomerates. Based on the analysis of the regional geology and exploitation marks, these three lithotypes have been recognised to crop out in the surroundings of Lixus and the quarries, presumably Roman in origin, recognized. The Oligocene sandstone is the primary building stone in Lixus as it forms and crops out extensively in the Tchemmis hill, at the top of which the city is settled. The Quaternary sandstones and conglomerates, which represent nearshore deposits and eolianites, crop out along the Atlantic coast where they form part of the cliffs next to Larache. Petrographic results indicate that lithotypes differ notably in grain size, ratio of detrital to allochemical components, and the configuration of their porous system. Mechanical analysis shows that the Oligocene sandstones are more resistant to compression than the Quaternary sandstones and conglomerates, the latter exhibiting relatively low compressive strength. The Oligocene sandstones, which display scarce porosity and permeability, show a hydric behaviour characterized by a very low degree of absorption and desorption water, likely resulting from a poor connectivity of the pore network. Contrary to the latter lithotype, the Quaternary sandstones, which exhibit very high porosity and permeability, display a hydric behaviour characterized by high degree of both absorption and desorption of water. This is attributed to the low degree of cementation compared to porosity of this lithotype and the excellent connectivity of the porous network. Finally, Oligocene and Quaternary sandstones do not show a significant weight loss after the accelerated artificial aging test, indicating that both are slightly affected by salt crystallization and presumably ice formation. Results indicate that the relatively fine state of conservation of the building rocks of Lixus is linked to intrinsic factors such as mineralogy and petrophysical characteristics together with the favourable effect of the climatic condition of the study area.","PeriodicalId":55107,"journal":{"name":"Geologica Acta","volume":"18 1","pages":"1-16"},"PeriodicalIF":1.5,"publicationDate":"2020-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44125896","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Geometry and kinematics of the Baza Fault (central Betic Cordillera, South Spain): insights into its seismic potential","authors":"I. Medina-Cascales, I. Martin-Rojas, F. García-Tortosa, J. Peláez, P. Alfaro","doi":"10.1344/geologicaacta2020.18.11","DOIUrl":"https://doi.org/10.1344/geologicaacta2020.18.11","url":null,"abstract":"The geometry and kinematics of active faults have a significant impact on their seismic potential. In this work, a structural characterization of the active Baza Fault (central Betic Cordillera, southern Spain) combining surface and subsurface data is presented. Two sectors are defined based on their surface geometry: a northern sector striking N–S to NNW–SSE with a narrow damage zone and a southern sector striking NW–SE with a wide damage zone. A kinematic analysis shows pure normal fault kinematics along most of the fault. Geometric differences between the northern and southern sectors are caused by i) a heterogeneous basement controlling the fault geometry at depth and in the cover; ii) different orientations of the Baza Fault in the basement with respect to the regional extension direction and iii) interaction with other active faults. We use this structural characterization to analyse the segmentation of the Baza Fault. According to segmentation criteria, the entire Baza Fault should be considered a single fault seismogenic segment. Consequently, the seismic potential of the fault is defined for a complete rupture. Magnitude for the Mmax event is calculated using several scale relationships, obtaining values ranging between Mw 6.6 and Mw 7.1. Recurrence times range between approximately 2,000 and 2,200 years for Mmax events and between 5,300 and 5,400 years for palaeo-events. A geodetic scenario modelled for an Mmax event of Mw 6.7 shows permanent vertical displacements of more than 0.40m and an overall WSW–ENE extension during entire ruptures of the Baza Fault.","PeriodicalId":55107,"journal":{"name":"Geologica Acta","volume":"18 1","pages":"1-25"},"PeriodicalIF":1.5,"publicationDate":"2020-08-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45323768","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Wildfire evidence from the Middle and Late Permian Hanxing Coalfield, North China Basin","authors":"L. Xiao, Q. Zhao, J. Wang, V. Mishra, S. Arbuzov, M. Zhang","doi":"10.1344/geologicaacta2020.18.12","DOIUrl":"https://doi.org/10.1344/geologicaacta2020.18.12","url":null,"abstract":"Earth has a long geological history and palaeo-wildfire is one of the key factors which is responsible for the evolution and extinction of our earth systems. The most important extinction of our earth systems is the Permian-Triassic mass extinction. The objective of this paper is to evaluate the product of wildfire in terms of distribution and occurrences from the Late Permian North China basin. Fourteen rock samples were collected from a drill core of Hanxing Coalfield of North China basin. The samples were analyzed by macro and micro petrography, Scanning Electron Microscopy (SEM), Gas Chromatography (GC) and Gas Chromatography–Mass Spectrometry (GC-MS) in order to study the evidence of wildfire. Charcoal (inertinite) particles are observed in the samples, which established the occurrences of wildfire during the upper Middle and Late Permian time in North China. Additionally, high-molecular-weight Polycyclic Aromatic Hydrocarbons (PAHs) were detected in the studied samples which also reinforce the presence of palaeo–wildfire events in the North China basin in Late Permian due to the fact that these aromatic compounds were formed under high temperatures.","PeriodicalId":55107,"journal":{"name":"Geologica Acta","volume":"18 1","pages":"1-11"},"PeriodicalIF":1.5,"publicationDate":"2020-08-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41502968","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Neogene and Quaternary deposits of the Barcelona city through the high-speed train line","authors":"J. M. Salvany, J. Aguirre","doi":"10.1344/geologicaacta2020.18.10","DOIUrl":"https://doi.org/10.1344/geologicaacta2020.18.10","url":null,"abstract":"A total of 208 boreholes with continuous core sampling, drilled for the construction of the high-speed train line through the city of Barcelona and other nearby infrastructures, were studied. The correlation of the lithologic logs of these boreholes allows identifying five main depositional sequences bounded by sharp erosional surfaces: i) lower Miocene, of alluvial origin; ii) middle Miocene, of deltaic-lacustrine origin; iii) lower Pliocene, of beach-shelf origin; iv) Pleistocene, of alluvial origin and v) Holocene, of deltaic origin. The erosive surfaces that separate these sequences represent important erosive hiatus linked to prolonged sea level falls at regional scale, which eliminated the upper part of each one. Sedimentation took place during decreasing intensity of extensional tectonic activity that mainly affected the Miocene deposits. The Plio-Quaternary units show their original structure apparently without tectonic alterations. Some new biostratigraphic data based on foraminifer assemblages allowed making accurate estimate of the age of the deposits.","PeriodicalId":55107,"journal":{"name":"Geologica Acta","volume":"18 1","pages":"1-19"},"PeriodicalIF":1.5,"publicationDate":"2020-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45644614","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Customization, extension and reuse of outdated hydrogeological software","authors":"A. Serrano-Juan, R. Criollo, E. Vázquez-Suñé, M. Alcaraz, C. Ayora, V. Velasco, L. Scheiber","doi":"10.1344/geologicaacta2020.18.9","DOIUrl":"https://doi.org/10.1344/geologicaacta2020.18.9","url":null,"abstract":"Each scientist is specialized in his or her field of research and in the tools that he or she uses during the research in a specified site. Thus, he or she is the most suitable person for improving the tools by overcoming their limitations to realize faster and higher quality analysis. However, most scientists are not software developers. Hence, it is necessary to provide them with an easy approach that enables non-software developers to improve and customize their tools. This paper presents an approach for easily improving and customizing any hydrogeological software. It is the result of experiences with updating several interdisciplinary case studies. The main insights of this approachhave been demonstrated using four examples: MIX (FORTRAN-based), BrineMIX (C++-based), EasyQuim and EasyBal (both spreadsheet-based). The improved software has been proven to be a better tool for enhanced analysis by substantially reducing the computation time and the tedious processing of the input and output data files.","PeriodicalId":55107,"journal":{"name":"Geologica Acta","volume":"1 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2020-06-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41537003","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}