scholarly journals Local depressions in country rock of kimberlites as a new exploration criteria (by the Example of Zolotitsa Field, Arkhangelsk, Russia)

2019 ◽  
Keyword(s):  
Country Rock ◽  
Exploration Criteria

scholarly journals Rapid alteration of fractured volcanic conduits beneath Mt Unzen

2021 ◽  
Vol 83 (5) ◽  
Author(s):  
Tim I. Yilmaz ◽  
Fabian B. Wadsworth ◽  
H. Albert Gilg ◽  
Kai-Uwe Hess ◽  
Jackie E. Kendrick ◽  
...  
Keyword(s):  
Country Rock ◽  
Geophysical Methods ◽  
Hydrothermal Fluids ◽  
Deep Drilling ◽  
Stress Regime ◽  
Argillic Alteration ◽  
Carbon And Oxygen Isotope ◽  
Propylitic Alteration ◽  
Indirect Information

AbstractThe nature of sub-volcanic alteration is usually only observable after erosion and exhumation at old inactive volcanoes, via geochemical changes in hydrothermal fluids sampled at the surface, via relatively low-resolution geophysical methods or can be inferred from erupted products. These methods are spatially or temporally removed from the real subsurface and thus provide only indirect information. In contrast, the ICDP deep drilling of the Mt Unzen volcano subsurface affords a snapshot into the in situ interaction between the dacitic dykes that fed dome-forming eruptions and the sub-volcanic hydrothermal system, where the most recent lava dome eruption occurred between 1990 and 1995. Here, we analyse drill core samples from hole USDP-4, constraining their degree and type of alteration. We identify and characterize two clay alteration stages: (1) an unusual argillic alteration infill of fractured or partially dissolved plagioclase and hornblende phenocryst domains with kaolinite and Reichweite 1 illite (70)-smectite and (2) propylitic alteration of amphibole and biotite phenocrysts with the fracture-hosted precipitation of chlorite, sulfide and carbonate minerals. These observations imply that the early clay-forming fluid was acidic and probably had a magmatic component, which is indicated for the fluids related to the second chlorite-carbonate stage by our stable carbon and oxygen isotope data. The porosity in the dyke samples is dominantly fracture-hosted, and fracture-filling mineralization is common, suggesting that the dykes were fractured during magma transport, emplacement and cooling, and that subsequent permeable circulation of hydrothermal fluids led to pore clogging and potential partial sealing of the pore network on a timescale of ~ 9 years from cessation of the last eruption. These observations, in concert with evidence that intermediate, crystal-bearing magmas are susceptible to fracturing during ascent and emplacement, lead us to suggest that arc volcanoes enclosed in highly fractured country rock are susceptible to rapid hydrothermal circulation and alteration, with implications for the development of fluid flow, mineralization, stress regime and volcanic edifice structural stability. We explore these possibilities in the context of alteration at other similar volcanoes.

Physical properties and seismic imaging of massive sulfides

Geophysics ◽  
2000 ◽  
Vol 65 (6) ◽  
pp. 1882-1889 ◽  
Author(s):  
Matthew H. Salisbury ◽  
Bernd Milkereit ◽  
Graham Ascough ◽  
Robin Adair ◽  
Larry Matthews ◽  
...  
Keyword(s):  
Physical Properties ◽  
Seismic Imaging ◽  
Country Rock ◽  
Imaging Techniques ◽  
Geometric Constraints ◽  
Eastern Canada ◽  
Massive Sulfides ◽  
Ore Bodies ◽  
Text Density ◽  
Representative Samples

Laboratory studies show that the acoustic impedances of massive sulfides can be predicted from the physical properties ([Formula: see text], density) and modal abundances of common sulfide minerals using simple mixing relations. Most sulfides have significantly higher impedances than silicate rocks, implying that seismic reflection techniques can be used directly for base metals exploration, provided the deposits meet the geometric constraints required for detection. To test this concept, a series of 1-, 2-, and 3-D seismic experiments were conducted to image known ore bodies in central and eastern Canada. In one recent test, conducted at the Halfmile Lake copper‐nickel deposit in the Bathurst camp, laboratory measurements on representative samples of ore and country rock demonstrated that the ores should make strong reflectors at the site, while velocity and density logging confirmed that these reflectors should persist at formation scales. These predictions have been confirmed by the detection of strong reflections from the deposit using vertical seismic profiling and 2-D multichannel seismic imaging techniques.

scholarly journals The Tikiusaaq carbonatite: a new Mesozoic intrusive complex in southern West Greenland

2006 ◽  
Vol 10 ◽  
pp. 41-44 ◽  
Author(s):  
Agnete Steenfelt ◽  
Julie A. Hollis ◽  
Karsten Secher
Keyword(s):  
Lithospheric Mantle ◽  
Chemical Elements ◽  
Country Rock ◽  
Alkaline Rock ◽  
Geological Mapping ◽  
Carbonatite Complex ◽  
West Greenland ◽  
Alkaline Rocks ◽  
Kimberlite Indicator Minerals ◽  
Indicator Minerals

Ultrabasic alkaline magmatic rocks are products of melts generated deep within or at the base of the lithospheric mantle. The magmas may reach the surface to form lavas and pyroclastic deposits; alternatively they crystallise at depth to form dykes or central complexes. The rocks are chemically distinct and may contain high concentrations of economically interesting minerals and chemical elements, such as diamonds, niobium, tantalum, rare earth elements, phosphorus, iron, uranium, thorium, and zirconium. Ultrabasic alkaline rocks are known from several provinces in Greenland, but extrusive facies have only been preserved at a few places; e.g. at Qassiarsuk in South Greenland where pyroclastic rocks occur, and in the Maniitsoq region, where a small volcanic breccia (‘Fossilik’) contains fragments of Palaeozoic limestone. Ultramafic lamprophyre and kimberlite are mainly emplaced as dykes, whereas carbonatite forms large intrusive bodies as well as dykes. The ultrabasic alkaline magmas that have been emplaced at certain times during the geological evolution of Greenland can be related to major episodes of continental break-up (Larsen & Rex 1992). The oldest are Archaean and the youngest dated so far are Palaeogene. Figure 1 shows the distribution of known ultrabasic alkaline rocks in West Greenland. The large and well-exposed bodies of alkaline rocks and carbonatites in the Gardar Province were discovered already in the early 1800s (Ussing 1912), while less conspicuous bodies were discovered much later during geological mapping and mineral exploration. Many alkaline rock bodies, particularly dykes, are difficult to identify in the field because they weather more extensively than the country rock gneisses and form vegetated depressions in the landscape. However, their distinct chemistry and mineralogy render alkaline rocks identifiable in geochemical and geophysical survey data. Thus, the Sarfartôq carbonatite complex was discovered during regional airborne gamma-spectrometric surveying owing to its elevated uranium and thorium contents (Secher 1986). The use of kimberlite indicator minerals has led to the discovery of alkaline rocks such as kimberlites and ultramafic lamprophyres that carry fragments of deep lithospheric mantle. Such rocks may also contain diamonds. Kimberlite indicator minerals are high-pressure varieties of minerals, such as garnet, clinopyroxene, chromite and ilmenite that were formed in the lithospheric mantle. Exploration companies have processed thousands of till samples from southern West Greenland for kimberlite indicator minerals and found many new dykes.

scholarly journals The Impact of Rock Music on Indian Young Adults: A Qualitative Study on Emotions and Moods

2021 ◽  
Vol 11 (4) ◽  
pp. 5361-5374
Author(s):  
Manaswini Tripathy ◽  
Mithunchandra Chaudhari
Keyword(s):  
Young Adults ◽  
Interpersonal Relationships ◽  
Rock Music ◽  
Qualitative Methodology ◽  
Social Issues ◽  
Country Rock ◽  
Vital Role ◽  
Self Control ◽  
Positive Effects ◽  
The Impact

Music has proven to play a vital role in social and emotional development in teenagers and young adults. From contemplation, developing self-identity, understanding interpersonal relationships, and providing possibilities of experience mastery, agency, and self-control with the help of self-directed activities, music helps its audience develop in all aspects of life. In specific, Rock music, since its existence has been more than entertainment, artists expressed themselves and shared their opinions through their musical pieces. Infamous for promoting drugs and alcohol, Rock Music used its platform to enlighten the audience about taboo topics like racism, inequality, and other social issues. This research paper uses a qualitative methodology approach to understand Rock Music listeners’ points of view. Data was collected through ‘in-depth interviews’ of 15 participants hailing from different parts of the country. Rock Music has several positive effects on the listeners. Rock can elevate moods, induce emotions, helps the listeners be more productive and creative with their everyday work, and constantly motivate them to do better in every aspect of life. Rock provides a platform to express feelings and vent out all the angst, especially for those who otherwise do not voice their opinions because of their nature in general. Rock Music has been able to shape personalities, characteristics, and thought processes. Moreover, majorly, Rock Music helps people with anger management.

The geochemical evolution of Nb–Ta–Sn oxides from pegmatites of the Cape Cross–Uis pegmatite belt, Namibia

2018 ◽  
Vol 83 (02) ◽  
pp. 161-179 ◽  
Author(s):  
Warrick C. Fuchsloch ◽  
Paul A. M. Nex ◽  
Judith A. Kinnaird
Keyword(s):  
Country Rock ◽  
Minor Element ◽  
Aqueous Fluid ◽  
Geochemical Evolution ◽  
Rare Element ◽  
Fractionation Process ◽  
North Central ◽  
Mineral Inclusions ◽  
Late Stages ◽  
Zonation Patterns

AbstractThe Cape Cross–Uis pegmatite belt, Damara Orogen, north-central Namibia hosts multiple Ta–Nb- and Sn-oxide-bearing pegmatites. Columbite-group minerals, tapiolite, cassiterite and minor ixiolite and wodginite occur in abundance within pegmatites and display various compositional and internal structural mineralogical variations. Ta–Nb oxides display various zonation patterns indicative of multiple crystallisation phases, whereas cassiterite is dominantly homogeneous with minor euhedral columbite-group mineral inclusions. Ta–Nb oxides are mostly rich in Fe, with fractionation patterns in the columbite quadrilateral being sub parallel to the Ta/(Ta + Nb) axis; increasing Ta/(Ta + Nb) with little change in Mn/(Mn + Fe), which is consistent with classical trends in beryl-to-spodumene rare-element pegmatites. In addition, these trends suggest that co-crystallising minerals compete with Ta–Nb oxides for elements such as Mn, preventing Ta–Nb oxides from attaining Mn-rich compositions during the fractionation process. Cassiterite shows similar fractionation patterns with Fe > Mn and notable increases in the Ta content. Minor-element substitution in Ta–Nb oxides shows sharp decreases with increasing fractionation supporting the hypothesis that newly stabilised co-occurring minerals compete with columbite-group minerals for certain elements. Tapiolite shows the same minor-element trend, however, only for Sn and Ti suggesting cassiterite was a dominant competing mineral. Although crystallisation of Ta–Nb oxides from an aqueous fluid at the late-stages of pegmatite genesis is highly debated, significantly elevated Ta contents in metasomatised country rock, compared to unaltered country rock, may give new insight, suggesting that Ta may indeed partition into, and be transported by, an exsolved aqueous fluid. However, further studies of the country rock metasomatic contacts are required as currently the dataset is limited. The degree of fractionation as depicted by Ta–Nb and Sn oxides within pegmatites, indicate that a zonation from primitive to evolved pegmatites surrounding granites is not present and that pegmatites are probably not related to granites in the typical parent–daughter relationship.

Late Carboniferous Schlingen in the Gotthard nappe (Central Alps) and their relation to the Variscan evolution

2021 ◽  
Author(s):  
Mario Buehler ◽  
Roger Zurbriggen ◽  
Alfons Berger ◽  
Marco Herwegh ◽  
Daniela Rubatto
Keyword(s):  
Shear Zone ◽  
Country Rock ◽  
Structural Evolution ◽  
Point Of View ◽  
Swiss Alps ◽  
Low Grade ◽  
Central Alps ◽  
Structural Investigations ◽  
Alpine Belt ◽  
Main Cluster

<p>Many pre‐Mesozoic basements of the Alpine belt contain kilometre‐scaled folds with steeply inclined axial planes and fold axes. Those structures are referred to as Schlingen folds. They deform polymetamorphic gneisses, often Late‐Ordovician metagranitoids and are cross‐cut themselves by Permian intrusions. However, the structural evolution of such Schlingen is still not completely understood and their geodynamic significance for the Variscan evolution is not clear. To close this gap, this study investigates in detail a well-preserved Schlingen structure in the Gotthard nappe (Central Swiss Alps). This Schlingen fold evolved by a combination of shearing and folding under amphibolite facies conditions. Detailed digital field mapping coupled with petrological and structural investigations reveal local synkinematic migmatisation in the fold hinges parallel to axial planes. U‐Pb dating of zircons separated from associated leucosomes reveal cores that record a detrital country rock age of 450 ± 3 Ma, and rims with a range of dates from 270 to 330 Ma. The main cluster defines an age of 316 ± 4 Ma. We ascribe this Late‐Carboniferous age to peak metamorphic conditions of the late‐Variscan Schlingen phase.</p><p>The pre-Schlingen structures are subdivided into three older deformation events, which are connected to the Cenerian and post-Cenerian deformations. In addition, until now unknown, post Schlingen-, but pre-Alpine transpressional deformation have been detected and described. This superimposed deformation produced locally a low-grade foliation and minor undulation of the Schlingen structures.</p><p>The detail data of the investigated fold structures are linked with already described Schlingen folds in the wider Alpine realm, which all are concentrated in the most southern parts of the Variscides. From a geodynamic point of view and based on the new tectono-metamorphic constraints, we propose Schlingen formation preceded and concurred the crustal-scale transpressional tectonics of the East Variscan Shear Zone. This scenario separates, at least in a structural sense, the Southern Variscides from more northern parts (also Gondwana derived) inside Pangea, where Schlingen folds are absent.</p>

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