Contribution a la geologie des gisements de thorianite a Madagascar

1958 ◽  
Vol S6-VIII (5) ◽  
pp. 511-530
Author(s):  
Pierre Brenon
Keyword(s):  
Precambrian Basement ◽  
Basement Complex

Abstract Thorianite occurrences of southern Madagascar are found in diopside pyroxenites, plagioclasites, or marbles of the Tranomaro group in the Androyen series of the Precambrian basement complex. The mineralization shows very few features in common with the phlogopite mineralization of the Ampandrandava group, but both were probably contemporaneous. Origin of the thorianite is most simply and logically explained as due to precipitation of thorium hydrate in the magnesian marly-limy sediments which became the rocks of the Tranomaro group.

Electromagnetic Profiling for Groundwater in Precambrian Basement Complex Areas of Nigeria

1990 ◽  
Vol 21 (3) ◽  
pp. 205-216 ◽  
Author(s):  
A. Idowu Olayinka
Keyword(s):  
Water Supply ◽  
Complex Terrain ◽  
High Conductivity ◽  
The Other ◽  
Precambrian Basement ◽  
Basement Complex ◽  
Rural Water Supply ◽  
Well Yield ◽  
Rural Water ◽  
Borehole Drilling

Ground electromagnetic profiling, using a Geonics EM34-3 instrument, has been employed to identify areas of high conductivity in a Precambrian basement complex terrain of Nigeria. Field examples, conducted as part of a rural water supply programme, are presented. They indicate that the apparent conductivities are generally lower than about 60 mmho m−1. Subsequent borehole drilling suggests a good correlation between high EM34 anomalies, deep weathering and high well yield (> 1 1 s−1). On the other hand, boreholes sited on conductivity lows penetrated a thinner regolith with relatively lower yields.

Integrating aeromagnetic and Landsat™ 8 data into subsurface structural mapping of Precambrian basement complex

2017 ◽  
Vol 125 ◽  
pp. 202-213 ◽  
Author(s):  
John Stephen Kayode ◽  
M.N.M. Nawawi ◽  
Khiruddin B. Abdullah ◽  
Amin E. Khalil
Keyword(s):  
Precambrian Basement ◽  
Basement Complex ◽  
Structural Mapping

scholarly journals Mineralogy and Geochemistry of Residual Clay Occurrences in Idi-Ayunre and Akure Areas, Southwestern Nigeria

2015 ◽  
Vol 7 (4) ◽  
pp. 23 ◽  
Author(s):  
Adewole J. Adeola
Keyword(s):  
Raw Materials ◽  
Thermal Characteristic ◽  
Granite Gneiss ◽  
Industrial Applications ◽  
Precambrian Basement ◽  
X Ray Diffraction ◽  
Basement Complex ◽  
Southwestern Nigeria ◽  
X Ray ◽  
Porphyritic Granite

<p class="zhengwen">Three residual clay occurrences in Idi-Ayunre, and Akure areas which belong to the Precambrian basement complex of southwestern Nigeria were investigated for their mineralogical, chemical and industrial properties. The investigation was to evaluate their industrial applications and economic importance. The clay within the weathered profiles above banded gneiss at Idi-Ayunre is whitish with red spots, whereas the clays derived from profiles above porphyritic granite and granite gneiss in Akure are grayish and brown in color respectively.</p><p class="zhengwen">The X-ray diffraction studies show that kaolinite is the dominant clay mineral, goethite, microcline, quartz, albite are the major non clay minerals in the samples. Chemical data showed that the average values of SiO<sub>2</sub>, Al<sub>2</sub>O<sub>3</sub>, and Fe<sub>2</sub>O<sub>3</sub> were 52.3. 30.29 and 3.54 wt% respectively constituting 86.13% of the bulk compositions.</p>Evaluation of the clay thermal characteristic, firing colour, water absorption capacities and shrinkage values show that the brownish Idi-Ayunre clay, gray and brown Akure kaolinitic clays could serve as raw materials for ceramics, building bricks, and other structural wares

SEISMIC SURVEY IN THE REGION OF RECENT EARTHQUAKE ACTIVITY NEAR DENVER, COLORADO

Geophysics ◽  
1968 ◽  
Vol 33 (6) ◽  
pp. 915-925
Author(s):  
Ben F. Rummerfield ◽  
A. Peter Olson ◽  
D. B. Hoover
Keyword(s):  
Seismic Activity ◽  
Seismic Reflection ◽  
Geological Survey ◽  
Seismic Survey ◽  
Earthquake Activity ◽  
Precambrian Basement ◽  
Basement Complex

A seismic‐reflection survey was carried out near Denver, Colorado, for the U. S. Geological Survey, to determine if structures exist in the 12,000‐ft sedimentary section or in the Precambrian basement that might explain the recent earthquake activity. No major faults were revealed in the sedimentary section. Reflections from a steeply dipping horizon believed to be in the basement complex may be indicative of faulting; however, the magnitude cannot be ascertained, as reflection events cannot be correlated at these depths. The results of the survey suggest the possibility of monitoring and studying subsurface structural conditions and related parameters in regions of seismic activity and/or suspected zones of tectonic instability.

On the Origin and Deformation of the Fleur de Lys Metaconglomerate, Appalachian Fold Belt, Northwest Newfoundland

1974 ◽  
Vol 11 (8) ◽  
pp. 1168-1180 ◽  
Author(s):  
Maarten J. de Wit
Keyword(s):  
Finite Strain ◽  
Three Dimensional ◽  
The State ◽  
Precambrian Basement ◽  
Fold Belt ◽  
Basement Complex ◽  
Glacial Deposit ◽  
Metamorphic Zone

The results of a study of a deformed metaconglomerate from the Fleur de Lys Supergroup, which occupies the northwest metamorphic zone of the Appalachian–Caledonian orogen in northwest Newfoundland, are described.This Eocambrian conglomerate unconformably overlies a Precambrian basement complex and has previously been interpreted as a glacial deposit. Sedimentological evidence does not support such an interpretation, and the present study shows the conglomerate to be of probable fluviatile origin.The deformation of the deposit, reflected in the state of finite strain of the clasts, is clearly inhomogeneous on all scales. The clasts range from nondeformed to intensely deformed and their shapes vary from oblale to prolate ellipsoids. The finite strain is thought to be due to buckling and three-dimensional differential flattening at the basement-conglomerate interface.

U–Th–Pb and Rb–Sr ages in granite reference sample from southwestern Saskatchewan

1970 ◽  
Vol 7 (1) ◽  
pp. 184-187 ◽  
Author(s):  
J. N. Rosholt ◽  
Z. E. Peterman ◽  
A. J. Bartel
Keyword(s):  
Reference Sample ◽  
Biotite Granite ◽  
Drill Core ◽  
Precambrian Basement ◽  
Basement Complex

Concordant total rock 206Pb–238U, 207Pb–235U, 207Pb–206Pb, 208Pb–232Th and 87Sr–87Rb ages of 1805 ± 40, 1815 ± 55, 1820 ± 110, 1790 ± 60, and 1810 ± 50, in millions of years, respectively, were obtained on the reference sample of biotite granite. The sample is a piece of drill core from a depth of 7300 ft (~2225 m), about 80 ft (~24.4 m) below the top of the Precambrian basement complex, in southwestern Saskatchewan.

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