scholarly journals Influence of Clay, Calcareous Microfossils, and Organic Matter on the Nature and Diagenetic Evolution of Pore Systems in Mudstones

2019 ◽  
Vol 124 (1) ◽  
pp. 149-174 ◽  
Author(s):  
Eliza J. Mathia ◽  
Thomas F. T. Rexer ◽  
K. Mark Thomas ◽  
Leon Bowen ◽  
Andrew C. Aplin
Keyword(s):  
Organic Matter ◽  
Diagenetic Evolution ◽  
Calcareous Microfossils

Diagenetic evolution of a Late Silurian reef platform, Gaspé Basin, Quebec, based on cathodoluminescence petrography

1989 ◽  
Vol 26 (4) ◽  
pp. 791-806 ◽  
Author(s):  
Martine Savard ◽  
Pierre-André Bourque
Keyword(s):  
Organic Matter ◽  
Stable Isotope ◽  
Light Microscope ◽  
West Point ◽  
Burial Depth ◽  
Back Reef ◽  
Diagenetic Evolution ◽  
Reef Platform ◽  
Colour Alteration ◽  
Stable Isotope Data

Carbonate units of two facie of the platformal upper reef complex of the Late Silurian West Point Formation, Gaspé Peninsula, Quebec, were studied to decipher their diagenetic evolution. The two facies were a reef-margin facies and a back-reef to lagoonal facies. Under the light microscope, only three broad cement phases were recognized. In contrast, cathodoluminescence observation revealed seven distinct generations of cements and a plethora of additional diagenetic features such as fracturing, internal brecciation, sulfatization, and stylolitization. The first four generations of cement were early marine and confined to the reef-margin facies. The subsequent three cement generations evolved in shallow to deeper burial environments and affected the reef-margin facies and the back-reef to lagoonal facies. C and O stable-isotope data support these deductions. Fracturing, internal brecciation, stylolitization, sulfatization, and the generation of the latest cements occurred during compaction and postcompaction stages. Lithification of the facies was rapid, with the pores completely occluded before a maximum burial depth of about 1 km was attained (based on conodont colour-alteration indices, organic-matter maturation data, and overall post-Silurian paleogeography).

Lithofacies, Depositional Environment and Diagenetic Evolution of the Paleocene Patala Formation, Potwar Basin, Pakistan: Implication for Shale Gas Potential

2021 ◽  
Author(s):  
Nasar Khan ◽  
Rudy Swennen ◽  
Gert Jan Weltje ◽  
Irfan Ullah Jan
Keyword(s):  
Organic Matter ◽  
Shale Gas ◽  
Gas Reservoirs ◽  
Shallow Marine ◽  
Anoxic Conditions ◽  
Fine Grained ◽  
Potwar Basin ◽  
Diagenetic Evolution ◽  
Reservoir Assessment ◽  
Gas Potential

<p><span><strong>Abstract:</strong> Reservoir assessment of unconventional reservoirs poses numerous exploration challenges. These challenges relate to their fine-grained and heterogeneous nature, which are ultimately controlled by depositional and diagenetic processes. To illustrate such constraints on shale gas reservoirs, this study focuses on lithofacies analysis, paleo-depositional and diagenetic evolution of the Paleocene Patala Formation at Potwar Basin of Pakistan. Integrated sedimentologic, petrographic, X-ray diffraction and TOC (total organic carbon) analyses showed that the formation contained mostly fine-grained carbonaceous, siliceous, calcareous and argilaceous siliciclastic-lithofacies, whereas carbonate microfacies included mudstone, wackestone and packstone. The silicious and carbonaceous lithofacies are considered a potential shale-gas system. The clastic lithofacies are dominated by detrital and calcareous assemblage including quartz, feldspar, calcite, organic matter and clay minerals with auxiliary pyrites and siderites. Fluctuations in depositional and diagenetic conditions caused  lateral and vertical variability in lithofacies. Superimposed on the depositional heterogeneity are spatially variable diagenetic modifications such as dissolution, compaction, cementation and stylolitization. The δ</span><sup>13</sup><span>C and δ</span><sup>15</sup><span>N stable isotopes elucidated that the formation has been deposited under anoxic conditions, which relatively enhanced the preservation of mixed marine and terrigenous organic matter. Overall, the Patala Formation exemplifies deposition in a shallow marine (shelfal) environment with episodic anoxic conditions.</span></p><p><strong>Keywords</strong><strong>:</strong> Lithofacies, Organic Matter, Paleocene, Potwar Basin, Shale Gas, Shallow Marine.</p>

scholarly journals Unexpected enrichment of nitrogen during the diagenetic evolution of sedimentary organic matter

Fuel ◽  
1984 ◽  
Vol 63 (11) ◽  
pp. 1508-1510 ◽  
Author(s):  
Jean-Paul Boudou ◽  
André Mariotti ◽  
Jean-Louis Oudin
Keyword(s):  
Organic Matter ◽  
Sedimentary Organic Matter ◽  
Diagenetic Evolution

A model of the diagenetic evolution of coaly sedimentary organic matter

1984 ◽  
Vol 48 (6) ◽  
pp. 1357-1362 ◽  
Author(s):  
Jean-Paul Boudou ◽  
Régis Pelet ◽  
René Letolle
Keyword(s):  
Organic Matter ◽  
Sedimentary Organic Matter ◽  
Diagenetic Evolution

Mechanical extraction of microfossils

1989 ◽  
Vol 4 ◽  
pp. 99-100 ◽  
Author(s):  
Jean M. Berdan
Keyword(s):  
Sewing Needle ◽  
Binocular Microscope ◽  
Calcareous Microfossils ◽  
Working Distance ◽  
Mechanical Extraction ◽  
Ordinary Steel

The described techniques for extraction of microfossils are directed primarily at the extraction of calcareous microfossils from various types of limestone, although the same techniques may beused for some sandstones and shales. The equipment needed is not complicated; the most obvious is a good binocular microscope with a working distance of three or more inches, to allow manipulation of the rock from which the specimens are to be extracted. The magnification required depends on the size of the specimens, but should go up to at least 80x. Other essential tools are a pin vise with a chuck which will hold an ordinary steel sewing needle and a rotary dental machine or other grinding device which will accept a small thin carborundum wheel. The latter is useful for sharpening needles as well as for cutting specimens out of the rock. An additional useful item is a percussive device such as a mechanical engraver fitted with a chuck which will hold an old fashioned steel phonograph needle. This instrument is described in detail by Palmer (this volume, chapter 20). A dish of water and a fine (00000) camel's hairbrush are necessary to move the specimens, once freed, to a slide or other receptacle. A rock trimmer is useful for reducing large blocks of fossiliferous rock into pieces that can be handled under the microscope, although with some collections this can be done with a hammer and cold chisel. Some paleontologists prefer to crush their samples and then pick through the chips to find specimens; however, this technique tends to break spines and frills from highly ornamented forms and is not recommended unless the microfauna is known to consist mostly of smooth species. Most of the equipment mentioned above can be found in catalogs such as that of the Edmund Scientific Co., 101 E. Gloucester Pike, Barrington, N.J. 08007.

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