The Heavy Mineral Suites and Correlation of the Granites of Northern Brittany, the Channel Islands, and the Cotentin

1930 ◽  
Vol 67 (5) ◽  
pp. 218-240 ◽  
Author(s):  
A. W. Groves

The area studied includes the majority of the main granite masses north of the belt of Ordovician and Silurian rocks running eastwards from Quimper to around Vitré and Laval. The heavy minerals of the Channel Islands granites have already been described by the writer (1). In the present paper the work is extended to the northern half of Finistère, and the greater part of the Côtes-du-Nord, Ille-et-Vilaine, and Manche. It is confined for the most part to the granites, and comparisons are made with those of the Channel Islands in an endeavour to obtain more definite evidence as to the age of the Jersey “Newer” Granites.

1980 ◽  
Vol 17 (2) ◽  
pp. 244-253
Author(s):  
John Edward Callahan

Stream sediments from a 13 000 km2 previously glaciated area in central Labrador near Churchill Falls were examined for their heavy mineral content. The minus 0.25 mm (60 mesh) nonmagnetic heavy mineral fraction from 846 stream sediment samples consists mainly of magnetite, ilmenite. garnet, hornblende, epidote and minor clinopyroxene, orthopyroxene. kyanite. sillimanite, biotite. apatite, and zircon. Changes in the frequency distribution of epidote, hornblende, garnet, and sillimanite in the stream sediments correspond well with those reported in previously mapped underlying bedrock lithologies. The occurrence of kyanite and sillimanite, high concentrations of garnet and opaques (mainly ilmenite), and lower concentrations of hornblende and epidote were used to determine grades of regional metamorphism, resulting in revision of the geologic map of this area. Heavy minerals in glacial drift or fluvial deposits may be useful as an aid in mapping in glaciated areas.


GeoArabia ◽  
2004 ◽  
Vol 9 (4) ◽  
pp. 77-102 ◽  
Author(s):  
Mahbub Hussain ◽  
Lameed O. Babalola ◽  
Mustafa M. Hariri

ABSTRACT The Wajid Sandstone (Ordovician-Permian) as exposed along the road-cut sections of the Abha and Khamis Mushayt areas in southwestern Saudi Arabia, is a mediun to coarse-grained, mineralogically mature quartz arenite with an average quartz content of over 95%. Monocrystalline quartz is the dominant framework grain followed by polycrystalline quartz, feldspar and micas. The non-opaque heavy mineral assemblage of the sandstone is dominated by zircon, tourmaline and rutile (ZTR). Additional heavy minerals, constituting a very minor fraction of the heavies, include epidote, hornblende, and kyanite. Statistical analysis showed significant correlations between zircon, tourmaline, rutile, epidote and hornblende. Principal component R-mode varimax factor analysis of the heavy mineral distribution data shows two strong associations: (1) tourmaline, zircon, rutile, and (2) epidote and hornblende suggesting several likely provenances including igneous, recycled sedimentary and metamorphic rocks. However, an abundance of the ZTR minerals favors a recycled sedimentary source over other possibilities. Mineralogical maturity coupled with characteristic heavy mineral associations, consistent north-directed paleoflow evidence, and the tectonic evolutionary history of the region indicate a provenance south of the study area. The most likely provenances of the lower part (Dibsiyah and Khusayyan members) of the Wajid Sandstone are the Neoproterozoic Afif, Abas, Al-Bayda, Al-Mahfid, and Al-Mukalla terranes, and older recycled sediments of the infra-Cambrian Ghabar Group in Yemen to the south. Because Neoproterozic (650-542 Ma) rocks are not widespread in Somalia, Eritrea and Ethiopia, a significant source further to the south is not likely. The dominance of the ultrastable minerals zircon, tourmaline and rutile and apparent absence of metastable, labile minerals in the heavy mineral suite preclude the exposed arc-derived oceanic terrains of the Arabian Shield in the west and north as a significant contributor of the sandstone. An abundance of finer-grained siliciclastic sequences of the same age in the north, is consistent with a northerly transport direction and the existence of a deeper basin (Tabuk Basin?) to the north. The tectonic and depositional model presented in this paper differs from the existing model that envisages sediment transportation and gradual basin filling from west to east during the Paleozoic.


2020 ◽  
Vol 5 (1) ◽  
pp. 12-21
Author(s):  
Ali Mohammad ◽  
E.N. Dhanamjayarao

Pre and post monsoonal changes in the environment have led to a noticeable variation in sediment characteristics, heavy mineral concentrations and their distribution. The current study aimed to find out the effect of seasonal fluctuations on the concentration of heavy minerals along the coast and the variations in sediment textures and distribution. The study has revealed the effect of seasons on the sediments supply and its distribution along coast in the study area. The total heavy minerals concentrations are more in post monsoon than in pre monsoon and the concentration also increases from south to north in parts of the study area because of seasonal circulation of currents from south to north along the shore. The micro textural study of the heavy mineral grains from different locations in the study area revealed the mechanical and chemical erosions on the grain surfaces.


Clay Minerals ◽  
1984 ◽  
Vol 19 (3) ◽  
pp. 287-308 ◽  
Author(s):  
A. C. Morton

AbstractIntrastratal solution of detrital heavy minerals in North Sea Tertiary sandstones takes place in two different diagenetic settings, deep burial and acidic weathering. These are characterized by different orders of mineral stability: apatite, chloritoid, garnet, sphene and spinel are less stable in acidic weathering than in deep burial, whereas the reverse is true for andalusite, kyanite and sillimanite. Heavy-mineral dissolution patterns, therefore, do not follow one single order of stability but several, depending on the diagenetic environment in which the dissolution occurs. It seems from this that the relative order of stability for detrital heavy minerals is controlled by the chemistry of the interstitial waters, whereas the limits of persistence depend on pore-fluid temperature, rate of water throughput, and geological age. Because different diagenetic environments lead to differing orders of mineral stability, it may prove possible to elucidate certain aspects of the diagenetic history of a sandstone by heavy-mineral dissolution patterns.


2020 ◽  
Author(s):  
Hatice Nur Bayram ◽  
Asli Nur Uslu ◽  
Ali Erdem Bakkalbasi ◽  
Demet Kiran Yildirim ◽  
Zeynep Doner ◽  
...  

<p><strong>Geochemical and mineralogical characteristics of beach sand sediments in southwestern Black Sea: An approach to heavy mineral placers  </strong></p><p><strong> </strong><strong>Hatice Nur Bayram (1*), Aslı Nur Uslu (1), Ali Erdem Bakkalbaşı (1), Demet Kiran Yildirim (1), </strong><strong>Zeynep Doner (1), Ali Tugcan Unluer (1)</strong></p><p><strong> </strong>(1) Istanbul Technical University, Faculty of Mines, Department of Geological Engineering, Istanbul, Turkey (*[email protected])</p><p><strong>Abstract: </strong><strong> </strong></p><p>Coastal or beach placer deposits are enrichments of heavy minerals with significant metal content that have been mechanically formed. This work studies the geochemical and mineralogical characteristics of beach sand sediments of southwestern Black Sea, Turkey which cover approximately 20 km<sup>2</sup> area. The study area has 4 main geological units: Upper Cretaceous moderately-K kalkalkaline Istanbul volcanics, Oligocene Danismen Formation which is dominated by flood plain, marshy and lake environments, Upper Miocene-Pliocene Belgrad Formation which is dominated by terrestrial deposits, mostly gravel, sand and clay dominated and Quaternary formations which include sandy beaches, sand dunes and river alluvials.</p><p>A total of 8 beach sand samples were analyzed by X-ray Diffraction (XRD) and X-ray Fluorecance (XRF). Mineralogical compositions are mainly dominated by quartz, siderite, albite, calcite and minor amount of magnetite. Siderite-rich beach sands are observed in western part of the study area and mostly derived from Danismen Formation. Fe<sub>2</sub>O<sub>3</sub> contents of this area are determined up to 40%.  On the other hand, in eastern part of the study area REE-Th-U content of beach sands are relatively higher than source rocks which is defined as a high-Al moderately-K kalkalkaline felsic rocks. The highest HFSE concentration were determined in -250+125µm fraction which consists of 16.5% of eastern beach sand. In this fraction LREE-Zr-U content rise drastically. It can be considered that REE-LREE contents is related with monazite minerals and U contents is related with zircon minerals, considering the monazite and zircon minerals are resistant to weathering and likely to occur in the orthomagmatic phase in the source volcanics.</p><p><strong>Key words</strong>: Beach sand sediments; REE-Th-U; heavy minerals; southwestern of Black Sea; Turkey</p>


1979 ◽  
Vol 16 (12) ◽  
pp. 2219-2235 ◽  
Author(s):  
Q. H. J. Gwyn ◽  
A. Dreimanis

Two main source areas of heavy minerals in tills have been defined in the Great Lakes region: a source in the Superior and Southern Provinces and another in the Grenville Province. The Superior–Southern source is typified by low heavy mineral content and high epidote percentage in contrast to the Grenville source which has a high content of heavy minerals of which garnet, tremolite, and to a lesser extent sphene and orthopyroxene are characteristic. The Huron lobe tills have a mineral suite characteristic of the Superior–Southern source. Two subsources can be distinguished in the Superior–Southern area; however, they are too limited in extent to be characteristic of major glacial lobes. Two other subsources have been identified in the Grenville provenance area: a western Grenville subsource containing abundant garnet and having a low purple–red garnet ratio; and an eastern Grenville subsource distinguished by high garnet and tremolite content and a garnet ratio generally greater than one. The western and eastern Grenville subsources are the provenance areas for the tills of the Georgian Bay lobe and the Ontario–Erie lobe respectively. A possible third Grenville subsource in the Adirondack Mountains is distinguished from other Grenville sources by a lower heavy mineral content and more abundant orthopyroxene and magnetic minerals. This assemblage may be characteristic of the southern portion of the Ontario–Erie lobe.


Geologos ◽  
2013 ◽  
Vol 19 (1-2) ◽  
pp. 5-23 ◽  
Author(s):  
Bogusław Marcinkowski ◽  
Elżbieta Mycielska-Dowgiałło

Abstract The composition of heavy-mineral assemblages is one of the main textural features of sediments because they can have significant value for the interpretation of, among others, their depositional environment, their depositional processes, and their stratigraphic position. Distinctive features of heavy minerals include their resistance to chemical weathering and mechanical abrasion, their habit, and their density. These parameters are the most widely used in the heavy-mineral research of Quaternary deposits in Poland, as well as in such research in other countries conducted by Polish scientists. Several other heavy-mineral parameters can also be used in various types of interpretation. It is discussed whether heavy-mineral analysis is decisive in the evaluation of deposits or whether it plays mainly a role that may support evidence obtained by other types of analysis. The attention is mainly devoted to transparent heavy minerals; the significance of opaque heavy minerals for interpretational purposes is only mentioned.


2016 ◽  
Vol 2 (1) ◽  
Author(s):  
Udaya Kamiludin ◽  
Maman Surachman ◽  
Wayan Lugra

Sedimen permukaan dasar laut di perairan Paciran dan sekitarnya umumnya mengandung magnetit, hematit, limonit, piroksen, amfibol, biotit, pirit dan rutil. Ragam mineral berat ini terdapat pada satuan lanau pasiran, pasir lanauan dan pasir. Unsur utama pembentuk mineral berat yang terlihat dari analisis kimia berupa SiO2, Al2O3, Fe2O3, CaO, MgO, K2O,Na2O dan TiO2. Selain terbentuk secara mekanik endapan mineral berat ini, terutama magnetit dan pirit sebagian terbentuk secara insitu. The surficial sediments Paciran waters and its vicinity consist of magnetite, hematite, limonite, pyroxene, amphibole, biotite, pyrite and rutile. These heavy minerals can be found in sandy silt, silty sand and sand. The major elements of these heavy minerals can be seen from the chemical analysis as SiO2, Al2O3, Fe2O3, CaO, MgO, K2O,Na2O and TiO2. Another mechanical processes of these heavy mineral deposits, especialy magnetite and pyrite, some are formed authogenically.


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