Major Sedimentational Environments of Carbonate Rocks in Sedimentary Basins

2015 ◽  
pp. 13-28
Keyword(s):  
Carbonate Rocks ◽  
Sedimentary Basins

scholarly journals Trace element geochemistry of carbonates in the Jurassic Lusitanian Basin records mineral-fluid interactions

2019 ◽  
Vol 98 ◽  
pp. 01017
Author(s):  
Mário A. Gonçalves ◽  
Maja Vuckovic ◽  
Alfonso Fiorelli ◽  
Pedro Barrulas ◽  
José Mirão
Keyword(s):  
Trace Elements ◽  
Fluid Flow ◽  
Carbonate Rocks ◽  
Sedimentary Basins ◽  
Trace Element Geochemistry ◽  
Element Geochemistry ◽  
Chemical Signatures ◽  
Icp Ms ◽  
Mineral Interaction ◽  
Lusitanian Basin

Carbonate rocks in sedimentary basins are reactive and can record complex histories of events associated with fluid flow in these basins. These include processes of dolomitization and dedolomitization. In this work we provide some preliminary data where distinct calcite and dolomite generations in the Jurassic Lusitanian Basin were analysed by LA-ICP-MS for trace elements in order to characterize chemical signatures of fluid-mineral interaction. It was observed that different carbonate generations can preserve the range of certain trace metal concentrations, but later calcites have distinctly higher contents in REE, Th and U, and Ba. Dolomites also show distinct chemical signatures but lack of analytical and spatial resolution does not allow quantification of the precursor calcite relicts. However, these processes point to the action of basinal fluids triggered by distinct tectonic episodes and associated volcanic activity.

scholarly journals Origin of Drusy Dolomite Cement in Permo-Triassic Dolostones, Northern United Arab Emirates

Water ◽  
2021 ◽  
Vol 13 (14) ◽  
pp. 1908
Author(s):  
Howri Mansurbeg ◽  
Mohammad Alsuwaidi ◽  
Shijun Dong ◽  
Salahadin Shahrokhi ◽  
Sadoon Morad
Keyword(s):  
Stable Isotopes ◽  
Fluid Inclusion ◽  
United Arab Emirates ◽  
Carbonate Rocks ◽  
Sedimentary Basins ◽  
86Sr Ratio ◽  
Homogenization Temperatures ◽  
Calcite Cement ◽  
Dolomite Cement ◽  
Carbonate Deposits

While the characteristics and origin of drusy calcite cement in carbonate deposits is well constrained in the literature, little attention is paid to drusy dolomite cement. Petrographic observations, stable isotopes, and fluid-inclusion microthermometry suggest that drusy dolomite cement in Permo-Triassic conglomerate/breccia dolostone beds in northern United Arab Emirates has precipitated as cement and not by dolomitization of drusy calcite cement. The low 18OVPDB (−9.4‰ to −6.2‰) and high homogenization temperatures of fluid inclusions in drusy dolomite (Th = 73–233 °C) suggest that dolomitization was caused by hot basinal brines (salinity = 23.4 wt% NaCl eq.). The 13CVPDB values (+0.18‰ to +1.6‰) and 87Sr/86Sr ratio (0.708106 to 0.708147) indicate that carbon and strontium were derived from the host marine Permo-Triassic carbonates. Following this dolomitization event, blocky calcite (Th = 148 °C; salinity = 20.8 wt% NaCl eq.) precipitated from the hot basinal brines. Unravelling the origin of drusy dolomite cement has important implications for accurate construction of paragenetic sequences in carbonate rocks and decipher the origin and chemistry of diagenetic waters in sedimentary basins.

Silicification and mechanical stratigraphy control on flow pathways and hypogenic karst development in carbonate rocks

2021 ◽  
Author(s):  
Luca Pisani ◽  
Marco Antonellini ◽  
Francisco Hilario Bezerra ◽  
Augusto Auler ◽  
Jo De Waele
Keyword(s):  
Carbonate Rocks ◽  
Sedimentary Basins ◽  
Hydrocarbon Exploration ◽  
Northeastern Brazil ◽  
Petrophysical Properties ◽  
High Permeability ◽  
Mechanical Stratigraphy ◽  
Lithostratigraphic Units ◽  
Conduit System ◽  
Flow Pathways

<p>Fractured and karstified carbonate rocks are important targets for the hydrocarbon exploration industry as they usually represent very productive reservoirs. Most of the karst features in carbonate reservoirs are the result of rising fluid flow in deeply buried settings (i.e., hypogenic karst), whose origin and solutional efficiency are not connected to surface processes. Hypogenic conduits are often intercepted by drilling during hydrocarbon exploration, and their occurrence is sometimes associated with high-permeability horizons characterized by intense silicification. Silicification is a common diagenetic process in sedimentary basins, in which Si-rich fluids modify textures, mineralogy, and petrophysical properties of the host rock.  </p><p>We present the preliminary results of a multidisciplinary study performed in a cave developed within a mixed carbonate-siliciclastic succession of the Salitre Formation, in Northeastern Brazil (Calixto Cave). This cave offers the opportunity to study an accessible and extensive (more than 1 km long) conduit system associated with silicification. We performed a detailed stratigraphic and structural characterization of the sedimentary sequence in the cave, identifying different SiO<sub>2</sub> facies and textural associations. Furthermore, we described cave geometry and pattern by topographic and morphometric observations using terrestrial laser scanner 3D models. Petrographic observations at the optical microscope were complemented with porosity-permeability analyses on rock plugs, XRD, XRF, and SEM-EDX analyses to highlight composition and petrophysical properties of the different lithostratigraphic units in the cave.</p><p>We found that silicification and mechanical stratigraphy determined the formation of high-permeability and seal units, whose distribution was fundamental for controlling paleo-flow pathways, karstification, and the spatial-morphological organization of the resultant conduit system. Cave morphologies, evidence of silica dissolution, crystalline quartz deposits and their associated paragenesis suggest that the speleogenetic phase contributing to the main karst formation happened in deeply buried hypogenic conditions, involving rising alkaline fluids probably of hydrothermal origin.</p>

A general inverse method for modelling extensional sedimentary basins

2000 ◽  
Vol 12 (3-4) ◽  
pp. 219-226 ◽  
Author(s):  
P. Bellingham ◽  
N. White
Keyword(s):  
Inverse Method ◽  
Sedimentary Basins
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