III.—A Petrological Study of the Arthur's Seat Volcano

1956 ◽  
Vol 63 (1) ◽  
pp. 37-70 ◽  
Author(s):  
R. H. Clark
Keyword(s):  
Present State ◽  
Late Stage ◽  
Volcanic Rocks ◽  
Parental Magma ◽  
Magma Source ◽  
Chemical Analyses ◽  
Lower Carboniferous ◽  
Basaltic Rocks ◽  
History Of

SynopsisAethur's Seat is the remains of a dissected Lower Carboniferous volcano, from which were erupted a series of basaltic rocks representative of the province to which it belongs. The rocks occur as lavas, intrusions and tuffs, and include basalts of Dalmeny, Jedburgh, Dunsapie, Craiglockhart and Markle types, in addition to mugearite. For convenience the basalts of Dunsapie type have been subdivided into Normal and Feldspathic varieties.The volcano has been remapped; some minor departures from the six-inch Geological Survey map are recorded and certain changes in the numbering and classification of the lavas have been made.The petrographic characters of the various volcanic rocks are described in detail, with modal and chemical analyses. The composition of the parental magma of the volcano was probably very similar to that of Normal Dunsapie basalt. Markle and Craiglockhart types were produced as complementary differentiates of the parental liquid by a process of gravity differentiation, in which sinking of ferromagnesian crystals, particularly augites, played an important part. The basalts of Dalmeny and Jedburgh types, which in Arthur's Seat have strong chemical resemblances, probably represent only slightly differentiated parental magma. Concentrations of soda-rich volatiles produced intense albitisation in the Markle basalts and the mugearites. It is considered that the mugearites of Arthur's Seat crystallised initially as Jedburgh or Dalmeny types, and were altered to their present state during a deuteric phase.An attempt has been made to reconstruct the eruptive history of the volcano. The magma source appears to have been replenished with parental magma at least twice during the period of activity. The first and last eruptions were of Dunsapie basalt; the albitised products appeared at a fairly late stage.

scholarly journals IV.—The Volcanic History of Ireland

1874 ◽  
Vol 1 (5) ◽  
pp. 205-210
Author(s):  
Edward Hull
Keyword(s):  
Volcanic Rocks ◽  
Central Valley ◽  
Short Description ◽  
Lower Carboniferous ◽  
Volcanic History ◽  
The North ◽  
History Of ◽  
Similar Materials ◽  
Considerable Intensity

Carboniferous Period.—The Lower Carboniferous rocks, both of the North of England, of Scotland, and of Ireland, afford examples of contemporaneous volcanic action of considerable intensity. The so-called “toad-stones” of Derbyshire, and the great sheets of melaphyre, porphyrite, and ashes of the central valley of Scotland, forming the Kilpatrick, Campsie, and Dairy Hills, appear to have been erupted over the bed of the same sea as that in which were poured out similar materials in County Limerick, forming the well-known Carboniferous volcanic rocks of “the Limerick Basin.” These rocks have been already so fully described by several observers, that I shall confine myself to a very short description, such as is essential to the brief history of volcanic action which I am here endeavouring to draw up.

scholarly journals Genesis of Volcanic Rocks in the Zijinshan Ore District, SE China: Implications for Porphyry-Epithermal Mineralization

Minerals ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 200 ◽  
Author(s):  
Zheng-Zheng Feng ◽  
Zhong-Jie Bai ◽  
Hong Zhong ◽  
Wei-Guang Zhu ◽  
Shi-Ji Zheng
Keyword(s):  
Oxygen Fugacity ◽  
Volcanic Rocks ◽  
Crustal Contamination ◽  
Parental Magma ◽  
High Oxygen ◽  
Magma Source ◽  
High Water Content ◽  
High Oxygen Fugacity ◽  
Epithermal Mineralization ◽  
T Values

Volcanic rocks, as the extrusive counterparts of the mineralized intrusions, can provide important information on the magma source, petrogenesis, and metallogenic conditions of the coeval porphyry-epithermal system. Shanghang Basin volcanic rocks are spatially and temporally related to a series of adjacent porphyry-epithermal Cu–Au deposits, and they can be used as a window to study the related deposits. Two laser-ablation–inductively coupled plasma–mass spectrometry zircon U–Pb analyses of the volcanic rocks yield weighted mean ages of ~105 Ma, identical to the age of the coeval porphyry-epithermal mineralization. Rocks have SiO2 contents of 55.4 to 74.8 wt % and belong to the high-K to shoshonitic series, characterized by strong differentiation of light rare-earth elements (REEs) relative to heavy REEs (mean LaN/YbN = 16.88); enrichment in light REEs, Rb, Th, and U; and depletion in Nb, Ta, Zr, Hf, and Ti. The volcanic rocks display (87Sr/86Sr)i values of 0.709341 to 0.711610, εNd(t) values of −6.9 to −3.3 εHf(t) values of −3.95 to −0.30, and δ18O values of 6.07‰–6.79‰, suggesting that the parental magmas were derived from a mantle source enriched by subduction-related progress. SiO2 content shows a strong negative correlation with the contents of some major and trace elements, indicating that fractional crystallization played an important role in the generation of these rocks. A binary mixing model of Hf–O isotopes gives an estimated degree of crustal contamination of 30%. In addition, magnetite crystallized early, and the samples showed high zircon EuN/EuN* values (0.48–0.68), indicating that the parental magma had a high oxygen fugacity. The inferred suppression of plagioclase crystallization and increasing hornblende crystallization during magma evolution suggest that the magma was water rich. The high-water content and high oxygen fugacity of the magma promoted the dissolving of sulfides containing Cu and Au in the source area and contributed to the migration of ore-forming elements.

VII.—On the Base of the Sedimentary Series in England and Wales

1890 ◽  
Vol 7 (7) ◽  
pp. 308-315 ◽  
Author(s):  
J. F. Blake
Keyword(s):  
Present State ◽  
Volcanic Rocks ◽  
Sedimentary Rocks ◽  
Present Stage ◽  
England And Wales ◽  
Accurate Knowledge ◽  
Geological Magazine

As Dr. Callaway has asked in a recent Number of the Geological Magazine for the grounds on which I suggest that some of the volcanic rocks of Shropshire may perhaps be classed as Cambrian, I take this opportunity for bringing before your readers the present state of the inquiry into the nature and classification of the earliest sedimentary rocks in this country. This inquiry has been spoken of by Dr. Callaway as the “Archæan controversy”; but we must not necessarily call everything that is earlier than the Cambrian “Archasan,” any more than in old days it was right to call everything Precarboniferous “unfossiliferous greywacké”; nor should the inquiry be considered a controversy in its present stage, but rather a search for more accurate knowledge.

Paleozoic subduction of the Mongol-Okhotsk oceanic plate: insight from the petrogenesis of Ordovician to Devonian granitic plutons in the Hangay Range, central Mongolia

2021 ◽  
Author(s):  
jiaqi Ling ◽  
pengfei Li
Keyword(s):  
Tectonic Evolution ◽  
Magma Source ◽  
Oceanic Plate ◽  
Early Devonian ◽  
Central Mongolia ◽  
Middle Ordovician ◽  
Basaltic Rocks ◽  
History Of ◽  
Geochemical Studies ◽  
T Values

<p>Email: [email protected]; [email protected]</p><p> </p><p>The pre-Mesozoic subduction history of the Mongol-Okhotsk oceanic plate has been poorly understood. Here we conducted geochronological and geochemical studies on four granitic plutons in the westernmost Mongol-Okhotsk Orogen (Hangay Range), with an aim to understand their petrogenesis and role in the Paleozoic tectonic evolution of the Mongol-Okhotsk Orogen. Our geochronological results constrain four granitic plutons to be emplaced from middle Ordovician to early Devonian. Geochemically, the Ordovician pluton belongs to A2-type granites, and three Silurian to Devonian plutons show the characteristics of I-type granites. These granitic plutons were probably generated by partial melting of basaltic rocks in the lower crust given the high contents of Na<sub>2</sub>O and K<sub>2</sub>O. The negative ε<sub>Nd</sub>(t) values (-4.7 to -0.9) and variable ε<sub>Hf</sub>(t) values (-2.6 to +6.1) for the four granitic plutons suggest that ancient basement materials were possibly involved in the magma source. We further investigate the geodynamic origin of these plutons in the context of the Paleozoic tectonics of the Mongol-Okhotsk Orogen, and we conclude that they were probably formed in response to the Ordovician to Devonian subduction of the Mongol-Okhotsk oceanic plate.</p>

The mafic mineralogy of the Pandé massif, Tikar plain, Cameroon: implications for a peralkaline affinity and emplacement from highly evolved alkaline magma

2000 ◽  
Vol 64 (3) ◽  
pp. 525-537 ◽  
Author(s):  
E. Njonfang ◽  
C. Moreau
Keyword(s):  
Late Stage ◽  
Volcanic Rocks ◽  
Parental Magma ◽  
Coarse Grained ◽  
Water Dissociation ◽  
Magmatic Differentiation ◽  
Volcanic Sequence ◽  
Granite Basement ◽  
Volatile Loss ◽  
Intrusive Suite

AbstractThe Pandé massif is a small (4.9×63.4 km) subvolcanic complex of the Cameroon Line striking W – E and intrudes a Panafrican granite basement. It comprises a syenite-granite suite, where coarse- to finegrained syenites are predominant and the granites are the product of residual melt after syenite crystallization, and two volcanic (trachyte-rhyolite and trachyte) sequences. Amphibole and pyroxene are the dominant mafic silicates, the first occurring mainly in rhyolites and coarse- to medium-grained syenites, and the second, principally in all syenites, trachytes and granites. Rare biotite flakes are encountered in the coarse-grained or alkaline syenites and fayalite rimmed with oxides occurs in trachyte from the first volcanic sequence (T1). Apatite and zircon are common accessories, whereas some titanite occurs in the medium-grained syenites. The plutonic rocks are drusy, intrude the first volcanic sequence but pre-date the second (T2).All the mafic minerals are Fe-rich. Detailed studies of amphibole and pyroxene show that their compositions define relatively limited trends, amphibole varying from ferro-richterite to arfvedsonite and pyroxenes along the acmite-hedenbergite join of the Ac-Hd-Di diagram, in both the intrusive suite and volcanic rocks. Where the two minerals coexist, pyroxene crystallized subsequent to amphibole, a situation generally found in late-stage or subsolidus aegirines. The overlap in plutonic and volcanic pyroxene trends suggests their crystallization from magmas of the same composition. However, the presence of quartz and fayalite in T1 and of pure aegirine in T2 and the occurrence of Zr-bearing aegirine (NaZr0.5Fe0.52+Si2O6) in the early crystallizing alkaline syenites evolving towards pure aegirine from medium- to fine-grained quartz syenites and granites, are consistent with changes in oxygen fugacities during magmatic differentiation. Two stages are distinguished: fO2 increasingly decreased from T1 to alkaline syenite emplacement (from 10−16 to 10−24 bracketed by WM and QFM buffers) where a disequilibrium, probably caused by water dissociation with volatile loss (H2) during magma degassing, favoured crystallization of Zr-bearing aegirine; a decrease in amphibole proportions towards medium-grained quartz syenites and an increase in fO2 from the medium-grained quartz syenites to granites and T2 sequence.The Mg-poor nature of all the mafic silicates, subsolidus origin of amphiboles, crystallization of pyroxene subsequent to amphibole and subsolidus trends defined by pyroxenes are compatible with the parental magma having itself been a late-stage derivative magma, e.g. the last product of an alkaline melt from which the voluminous Mayo Darlé granite bodies crystallized.

scholarly journals Composição, leis de macla e estado estrutural dos plagioclásios de rochas vulcânicas da Bacia do Paraná

1980 ◽  
Vol 2 (2) ◽  
pp. 105
Author(s):  
Pedro Luiz Pretz Sartori
Keyword(s):  
Volcanic Rocks ◽  
Lava Flows ◽  
Optical Measurements ◽  
Basaltic Rocks ◽  
First Case ◽  
History Of ◽  
Paraná Basin ◽  
High Or Low Temperature ◽  
Parana Basin ◽  
Selection Of

Plagioclases of distinct lava flows of the Southern Paraná basin were optically determined through the laws of Albite-CarIsbad, Carlsbad and Albite twin, which are the most frequent.In the basaltic rocks of uniform granulation of the composition is in the range between An45-An65, with a concentration of values in the interval An50-An55. In the inequigranular types the phenocrysts, in general, display values above An60. In the first case, the plagioclases are of the volcanic and transition types; in the latter, the phenocrysts, commounly, are of the plutonic or transition types, in this way showing the thermic history of the rocks.The knowledge of the structural state of the plagioclase of volcanic rocks of the Paraná basin favours the precision of the optical measurements for the calculation of anorthite, allowing the selection of the most adequate determining curve (high or low temperature).

X-Ray Fluorescence of Rock Samples as Applied to Geological Problems

1968 ◽  
Vol 22 (5) ◽  
pp. 420-422 ◽  
Author(s):  
Richard A. Laidley
Keyword(s):  
Volcanic Rocks ◽  
Analytical Techniques ◽  
Compositional Variation ◽  
Chemical Analyses ◽  
Geologic History ◽  
X Ray ◽  
History Of ◽  
Precision And Accuracy ◽  
Rock Specimens

Three methods of sample preparation of rock specimens have been evaluated for precision and accuracy. A fusion technique was found to give the best precision. Standard deviations (1 σ) using this method and expressed as percent of the amount present for several elements are: Al 0.83, Si 0.64, K 0.43, Ca 0.43, Mn 0.48, Fe 0.24. Three recent studies of compositional variation were performed on volcanic rocks. Analyses of samples from the Hopi Buttes, Arizona, on obsidian flows from Newberry Caldera, Oregon, and on igneous rocks collected from grids or linear traverses give data which, in each case, are useful in making significant interpretations about the geologic history of the rocks concerned. These examples illustrate the rapidity and high quality of quantitative chemical analyses which can be obtained by application of x-ray fluorescence analytical techniques.

Tissue microarray based classification of early and late stage colorectal cancer in optical and virtual microscopy

2007 ◽  
Vol 45 (05) ◽  
Author(s):  
F Sipos ◽  
S Spisák ◽  
T Krenács ◽  
O Galamb ◽  
B Galamb ◽  
...  
Keyword(s):  
Colorectal Cancer ◽  
Tissue Microarray ◽  
Late Stage ◽  
Virtual Microscopy

To Understand the Informal (on the Book BY V. L. Tambovtsev “Economics of Informal Institutions”)

2015 ◽  
pp. 151-158
Author(s):  
A. Zaostrovtsev
Keyword(s):  
Social Psychology ◽  
Detailed Analysis ◽  
Human Behavior ◽  
Interdisciplinary Approach ◽  
Informal Institutions ◽  
Economic Thought ◽  
History Of ◽  
Original Classification

The review considers the first attempt in the history of Russian economic thought to give a detailed analysis of informal institutions (IF). It recognizes that in general it was successful: the reader gets acquainted with the original classification of institutions (including informal ones) and their genesis. According to the reviewer the best achievement of the author is his interdisciplinary approach to the study of problems and, moreover, his bias on the achievements of social psychology because the model of human behavior in the economic mainstream is rather primitive. The book makes evident that namely this model limits the ability of economists to analyze IF. The reviewer also shares the author’s position that in the analysis of the IF genesis the economists should highlight the uncertainty and reject economic determinism. Further discussion of IF is hardly possible without referring to this book.

Assessment criteria for aggregate social welfare

2020 ◽  
Vol 19 (12) ◽  
pp. 2358-2371
Author(s):  
S.A. Moskal'onov
Keyword(s):  
Social Welfare ◽  
Mathematical Analysis ◽  
Exchange Economy ◽  
Assessment Criteria ◽  
Impossibility Theorem ◽  
New Approaches ◽  
History Of Development ◽  
Arrow's Impossibility Theorem ◽  
History Of

Subject. The article addresses the history of development and provides the criticism of existing criteria for aggregate social welfare (on the simple exchange economy (the Edgeworth box) case). Objectives. The purpose is to develop a unique classification of criteria to assess the aggregate social welfare. Methods. The study draws on methods of logical and mathematical analysis. Results. The paper considers strong, strict and weak versions of the Pareto, Kaldor, Hicks, Scitovsky, and Samuelson criteria, introduces the notion of equivalence and constructs orderings by Pareto, Kaldor, Hicks, Scitovsky, and Samuelson. The Pareto and Samuelson's criteria are transitive, however, not complete. The Kaldor, Hicks, Scitovsky citeria are not transitive in the general case. Conclusions. The lack of an ideal social welfare criterion is the consequence of the Arrow’s Impossibility Theorem, and of the group of impossibility theorems in economics. It is necessary to develop new approaches to the assessment of aggregate welfare.

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