Matej Masný, Lubica Zaušková

Article number: 20150055

More Download PDF

Abstract

Socio-political changes in the countries of Easternand Central Europe in the era of socialism had significant effects on agricultural landscape. Collectivisation(1950 - 1970) lost almost all of traditional agricultural landscapes.On the other hand, the phenomenon of agriculturalabandonment started to be significant after 1989. Inthe model area (part of The Polana Biosphere Reserve)these two processes that formed the agricultural landscapestructure were analysed. The analyses were carriedout using orthophotos that represented the landscapestructure in 1949, 1986 and 2006. It was found that almostcomplete extinction of the traditional agricultural landscaperepresented by a mosaic of narrow fields and permanentgrasslands occurred during the period. At the sametime, increasing trend of abandonment processes was observed.In 2006, non-forestwoody vegetation covered 48%of agricultural land.Natural reforestation as the final stageof agricultural abandonment extended to 46% on the formeragricultural land in 2006. Abandonment processeswere the most significant already in the period of socialistagriculture. To describe the changes, landscape metricssuch as Number of patches (NP), Mean patch size (MPS),Patch size standard deviation (PSSD) and Mean shape index(MSI) were used.

Mafic-ultramafic rocks and alkaline-carbonatitic magmatism and associated hydrothermal mineralization: A special issue (Part-II)

Open Access October 29, 2015

A Special Issue (Part-II): Mafic-ultramafic rocks andalkaline-carbonatitic magmatism and associated hydrothermalmineralization - dedication to Lia Nikolaevna Kogarko

Lia N. Kogarko, Lalchand G. Gwalani, Peter J. Downes, Kirtikumar R. Randive

Article number: 20150025

More Download PDF

Abstract

This is the second part of a two-volumespecial issueof Open Geoscience (formerly Central European Journalof Geosciences) that aims to be instrumental in providingan update of Mafic-Ultramafic Rocks and Alkaline-Carbonatitic Magmatism and Associated HydrothermalMineralization. Together, these two volumes provide a detailedand comprehensive coverage of the subjects thatare relevant to the research work of P.Comin-Chiaramonti(Italy) and LiaN. Kogarko (Russia) towhomPart-I and Part-II have been respectively dedicated.To a significant extent, the development of advanced samplingtechnologies related to alkaline and carbonatiticmagmatism by Lia N. Kogarko, has allowed geoscientiststo measure and sample the deep crust of the planet notonly for the exploration for the mineral deposits, but alsoto answer basic scientific questions about the origin andevolution of alkaline rocks (kimberlites, lamproites and relatedrocks associated with carbonatites). The papers presentedin this Part-II of the special issue cover the petrologyand geochemistry of the rocks collected from the surfaceand penetrated by drilling. Lia Kogarko proposed anew theory for the evolution of alkaline magmatism in thegeological history of the Earth – that the appearance of alkalinemagmatism at the Archaean-Proterozoic boundary(~2.5 – 2.7 Ga), and its growing intensity, was related tochanges in the geodynamic regime of the Earth and oxidationof the mantle due to mantle-crust interaction.

Open Access August 11, 2015

A Special Issue (Part-II): mafic-ultramafic rocks andalkaline-carbonatitic magmatism and associated hydrothermalmineralization – dedication to Lia N. Kogarko

Lalchand Govindram Gwalani, Ken Rogers, Francesco Stoppa, Peter J. Downes, Kirtikumar Randive, K.R. Hari, Michał Bucha

Article number: 20150026

The southern part of the Bundelkhand cratoncontains a series of a E-W trending mafic and ultramaficrocks, about 40 km in length and 2–4 km wide, that occuras intrusions within the Bundelkhand Gneissic Complex(BnGC). They are confined between the Madawara-Karitoran and Sonrai-Girar shear zones. Dunite, harzburgite,lherzolite and websterite are the commonly occurringultramafic rocks that have high MgO, Ni, Cr, PGE andlow Al2O3, CaO, K2O, TiO2 and V contents, and showsperidotitic affinity. A distinct trend of crystallization fromperidotite to komatiitic basalt has been inferred from geochemicalplots, which also indicates the occurrence ofat least two varieties among the ultramafic suite of theMadawara ultramafic complex, namely, Group I comprisingdunite, spinel peridotite, harzburgite and lherzolite,and Group II consisting of pyroxenite, websterite andolivine websterite. In several places, the rocks of Group IIhave an intrusive relationship with Group I, and are relativelyenriched in total platinum group elements (PGE ~300 ppb). The discrimination diagrams suggest that thePGE are enriched in low sulphur-fugacity source magma atmoderate to deeper depths by high degree of partial meltingof the mantle.

About this journal

Open Geosciences is an open access, peer-reviewed journal publishing original research results from all fields of Earth Sciences. The aim of the journal is to become the premier source of high-quality research from all over the world. Open Geosciences is designed to facilitate the exchange of ideas between experienced and young researchers from different countries.

Aims and Scope

Subject areas suitable for publication include, but are not limited to, the following: Atmospheric Sciences, Geology, Geophysics, Geochemistry, Geography, Oceanography and Hydrology, Glaciology, Speleology, Volcanology, Soil Science, Palaeoecology, Geotourism, Geoinformatics, Geostatistics, Geoengineering, and Remote Sensing.