Similarities in groundwater occurrence in weathered and fractured crystalline basement aquifers in the Channel Islands and in Zimbabwe

2014 ◽  
pp. 69-82 ◽  
Keyword(s):  
Crystalline Basement ◽  
Channel Islands ◽  
Groundwater Occurrence ◽  
Basement Aquifers

scholarly journals The role of geological structures on groundwater occurrence and flow in crystalline basement aquifers: a status review

2018 ◽  
Vol 11 (1) ◽  
pp. 155-164
Author(s):  
M.A. Idris ◽  
M.L. Garba ◽  
S.A. Kasim ◽  
I.M. Madabo ◽  
K.A. Dandago
Keyword(s):  
Hydrological Cycle ◽  
Crystalline Basement ◽  
Geological Structures ◽  
Secondary Porosity ◽  
Groundwater Movement ◽  
Remote Sensing Technique ◽  
Basement Rocks ◽  
Groundwater Occurrence ◽  
Basement Aquifers

The paper is review on the role of geological structures on groundwater occurrence and flow in Crystalline Basement aquifers. The aim was to study the existing available literatures in order to evaluate structural/lineaments (faults, joints/fractures, folds, shear zone etc.) their influences and controls of groundwater occurrence and flow of bedrock of crystalline rocks of igneous and/or metamorphic origin. Groundwater in the basement aquifers resides/occurs within the weathered overburden and fractured bedrocks which originate from rainfall through the process of hydrological cycle. Remote sensing technique uses satellite imagery or aerial photograph to identify linear features on the ground and attempts to relate these lines to geologic structures capable of transmitting and storing large quantities of groundwater. Faults, joints/fractures and folds act as conduit and make rocks excellent aquifers. These features also, served as channels for groundwater movement which may results to an increased in secondary porosity, permeability and therefore, can results as a groundwater prospective/promising zones in crystalline basement rocks. Keywords: Basement Terrain, Groundwater, Lineament, Movement, Occurrence

Review: Approaches to groundwater exploration and resource evaluation in the crystalline basement aquifers of Zimbabwe

2019 ◽  
Vol 27 (3) ◽  
pp. 915-928 ◽  
Author(s):  
Innocent Muchingami ◽  
Constant Chuma ◽  
Mervyn Gumbo ◽  
Dumisani Hlatywayo ◽  
Robin Mashingaidze
Keyword(s):  
Groundwater Exploration ◽  
Crystalline Basement ◽  
Resource Evaluation ◽  
Basement Aquifers

Crystalline basement aquifers of Ethiopia: Their genesis, classification and aquifer properties

2014 ◽  
Vol 100 ◽  
pp. 191-202 ◽  
Author(s):  
Gaddissa Deyassa ◽  
Seifu Kebede ◽  
Tenalem Ayenew ◽  
Tesfaye Kidane
Keyword(s):  
Crystalline Basement ◽  
Basement Aquifers ◽  
Aquifer Properties

scholarly journals Heterogeneity of hydrogeological conceptual models in crystalline basement aquifers under equatorial climate: case study of French Guiana

2021 ◽  
Author(s):  
Adrien Selles ◽  
Geoffrey Aertgeerts ◽  
Nicolas Brisset ◽  
Maxime Lhotelin
Keyword(s):  
French Guiana ◽  
Conceptual Models ◽  
Shear Zones ◽  
Crystalline Basement ◽  
Groundwater Resource ◽  
Guiana Shield ◽  
Confined Aquifer ◽  
Fractured Zone ◽  
Basement Rocks ◽  
Basement Aquifers

<p>Crystalline rocks aquifers are usually represented with a low porosity and hydraulic conductivity giving low well yields. Over the world, more than 880 millions people live on crystalline basement rocks. Thus, abilities to spot sufficient groundwater resource in these systems are crucial. Nevertheless, assessment of the sustainable reservoirs in crystalline basement aquifers is challenging. The well-admitted conceptual model presents a stratiform-weathered profile above a fractured zone showing a decreasing fracture density with depth. The interconnection between these two compartments defines the hydraulic parameters: the weathered profile is capacitive while the fractured zone is transmissive.</p><p>French Guiana is mostly composed of Paleoproterozoic rocks belonging to the Guiana Shield. It was formed during protracted periods of intense suprasubduction related magmatism, metamorphism and deformation, culminating with the Transamazonian orogeny, bracketed between 2.3 and 1.9 Ga. This peculiar geological history creates a large diversity of geological units from undeformed granitic units to ultramylonitized shears-zone related meta-volcano-sedimentary units and through brittle to ductile deformed units. Furthermore, over almost 200 Ma, the French Guiana recorded a deep weathering phase leading to heterogeneous and complex profiles up to 80-100 m deep. In such a context, hydrogeological exploration is thus puzzling, especially as French Guiana is covered by the Amazonian Forest, reducing direct observations.    </p><p>We use a multi-disciplinary method from remote sensing to field observations through geophysical tomography to propose conceptual models of groundwater circulation helping us to localise precisely (meter scale) exploration borewells. After 15 years of hydrogeological surveys, the BRGM has studied plural units: (i) classical isotropic unit (Mahury Massif (MM)) and Granitic unit (Mana), (ii) ductile to brittle deformed units separated by strike-slip fault (Rosebel-Bonidoro unit (RBU) and Armina Unit (AU)), (iii) ultramilonitized unit (Paramaca Unit (PU)). A large heterogeneity of hydrogeological conceptual models for each context arise from our results. Notwithstanding this diversity and thanks to these conceptualizations, we were able to propose successfully useable sustainable resources, confirming the robustness of the method.     </p><p>The MM and Mana are classical isotropic units displaying a deep weathered profile. The confined aquifer is located into the fractured layer with yield reaching 15 m<sup>3</sup>.h<sup>-1</sup>. Crosscutting dolerite dyke is attested to be an interesting hydrogeological target with yield near 20 m<sup>3</sup>.h<sup>-1</sup>. The highest yields in French Guiana for crystalline basement rocks (30 m<sup>3</sup>.h<sup>-1</sup>) are found in confined aquifer in PU context. This record could be due to the ultramylonitic deformation giving a high permeable unit. Three different places were studied for the AU (Sparouine, Roura, Beauséjour). As for the PU, aquifers are all confined. Yields are systematically low (around 2-5 m<sup>3</sup>.h<sup>-1</sup>). The RBU is an interesting and contrasting unit because it does not show developed weathered profile. It seems that an unconfined aquifer must probably recharge surroundings units (i.e. PU and AU).</p><p>This work highlights the high potential of ductile to ultramylonitic shear zones for groundwater resource. Taking together, these conceptual models highlight that, in French Guiana and probably in entire Guiana Shield, Transamazonian tectonometamorphic structures as well as early Jurassic extensive faults correspond to sustainable useable groundwater resources.</p>

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