High resolution cathodoluminescence spectroscopy of carbonate cementation in Khurmala Formation (Paleocene–L. Eocene) from Iraqi Kurdistan Region, Northern Iraq

Omer, Muhamed F.; Omer, Dilshad; Zebari, Bahroz G. A.

doi:10.1016/j.jafrearsci.2014.06.016

Cited by 9 publications

(4 citation statements)

References 36 publications

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“…Cathodoluminescence analyses (Fig. 4b) confirmed the nature of the clastic grains of the rhizoliths, with quartz grains in dark brown-blue (Mavris et al 2012;Omer 2015), feldspars in blue (alkali feldspar) or green (plagioclase) (Scholonek and Augustsson 2016), and lithogenic carbonates in orange (Omer et al 2014;Kolchugin et al 2016).…”

Section: Petrographymentioning

confidence: 73%

Genesis and soil environmental implications of intact in-situ rhizoliths in dunes of the Badain Jaran Desert, northwestern China

et al. 2022

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Desert rhizoliths are generally found as weathered, broken and scattered samples on dune field surface, but rarely in-situ in their initial states buried under the soil of desert in the Badain Jaran Desert, northwest China. This study offers an assessment of the morphological, mineralogical, and chemical properties of intact and in-situ rhizoliths found in soils of swales and depressions among dune chains. The characteristics of these rare and precious objects were assessed using optical polarizing microscopy, cathodoluminescence, scanning electronic microscopy, radiocarbon dating, and stable isotopic analyses, providing the opportunity for discussion of the rhizolith formation mechanisms and associated environmental conditions. Field and laboratory investigations showed that the in-situ intact rhizoliths were formed only in the places where Artemisia shrubs are living, and the remaining root relicts within rhizoliths belong to this species. The spatial distribution of rhizoliths also suggested that low topographic positions on a landscape provided soil moisture, and redox environments favored rhizolith formation. A semi-closed redox environment in the subsoil at swales and depressions, where water is always present, along with the sandy soil texture, facilitated fast water percolation to deeper depths and condensation. Such a soil environment not only provides water for Artemisia growth, but also for the weathering of minerals such as felspars and calcite from primary carbonates, and for the decomposition of root relicts. Furthermore, harsh climatic conditions, such as strong winds and solar radiation, led to water evaporation through dead root channels and triggered the calcification along the root relicts. The entrapped lithogenic carbonates and to a lesser extent the decomposition of Artemisia roots provided the carbon sources for the rhizoliths formation, while the weathering of soil minerals, particularly feldspars and carbonates, was the main source of Ca. Rhizoliths in the Badain Jaran desert formed relatively quickly, probably over a few soil drying episodes. This led to the entrapment of a large quantity of lithogenic carbonates (more than 90% of carbon) within rhizolith cement. The re-dissolution of the entrapped lithogenic carbonates in rhizolith tubes should be taken into account in the paleoenvironmental interpretation of 14C ages, the latter suggesting that rhizoliths formed during the Holocene (~ 2053 years cal BP, based on root organic relicts).

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Section: Petrographymentioning

confidence: 73%

Genesis and soil environmental implications of intact in-situ rhizoliths in dunes of the Badain Jaran Desert, northwestern China

et al. 2022

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“…Meteoric diagenesis at the top of the Ordovician Majiagou Formation in the Jingxi area is evident from four evidences of petrographic and geochemical data. Firstly, many irregular vuggy pores and fractures are developed in Sub‐members Ma5 5 and Ma5 6 , which are partly filled with karst residual fragments, argillaceous sediment, and calcite cement (Figure c–g), and the Ca1 calcite cements display complex yellow zonations occurring in otherwise dull orange luminescent calcites (Figure c,d), reflecting calcite precipitated under shallow burial conditions in a meteoric diagenetic environment that periodically changed in its chemistry (Moore, ; Omer, Omer, & Zebari, ). Secondly, the dolostone in Sub‐members Ma5 5 and Ma5 6 has higher SiO 2 , Al 2 O 3 , Fe 2 O 3 , and MnO contents than that in Sub‐member Ma5 10 , suggesting the influence of telogenetic karstification on dolomites (Huang, ), and the karstification intensity gradually decreased from Sub‐member Ma5 5 to Sub‐member Ma5 10 .…”

Section: Discussionmentioning

confidence: 99%

Seepage reflux dolomitization and telogenetic karstification in Majiagou Formation in the Ordos Basin, China

et al. 2018

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This study investigates the characteristics of the heterogeneous carbonate reservoir of Majiagou Formation in Jingxi area, Ordos Basin, China, to explain the diagenetic control and distribution of high‐quality reservoir intervals. The carbonates of the study area mainly consist of silt‐sized crystalline dolomite, microcrystalline dolomite, and microcrystalline limey dolomite. Both dolomite content and dolomite size gradually decrease both from top to bottom and from slope to basin. Intercrystalline pores exist in the silt‐sized crystalline dolomite, and vuggy pores and fractures mainly developed in microcrystalline (limey) dolomite. Furthermore, typical geopetal infills and three stages of calcite cements could be differentiated. Based on petrographical and geochemical analysis, the reservoir is dominantly controlled by seepage reflux dolomitization and telogenetic karstification. Four reservoir evolutions could be differentiated. The reservoir in the first model is dominated by intercrystal porosity occurring in silt‐sized crystalline dolostone. It experienced strong dolomitization, telogenetic karstification, and shallow as well as deep burial cementation. The reservoir in the second model consists of only a small amount of high‐angle dissolution fissures and vertical dissolution cavities in microcrystalline (limey) dolostone. It experienced relatively weak dolomitization, strong telogenetic karstification, and two important calcite cementation events. The reservoir in the third model is marked by many vuggy pores and dissolution fractures, occurring in microcrystalline (limey) dolostone. The strata experienced relatively weak dolomitization, strong telogenetic karstification, and two weak calcite cementation episodes. The reservoir in the fourth model is dominated by fractures and their related dissolution pores, which developed in microcrystalline (limey) dolostone. These dolostones experienced relatively weak dolomitization, telogenetic karstification, and calcite cementation. From a reservoir point of view, the reservoirs represented by the first and third models, which respectively are composed of silt‐sized crystalline dolomite occurring in the top of the whole dolostone succession and the dolomite affected by telogenetic karstification, are the most vital exploration targets.

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“…The prevailing dolomitization processes are related to early dolomitization in supratidal environment, and later dolomitization processes occurring during burial. In general, fine crystalline dolomites are predominant in mudstone and wackestone microfacies at the base of the log, whereas medium to coarse crystalline dolomites are more common in grain-supported facies (Omer et al 2014), mostly dominating the upper part of the log. In all cases, the different dolomitization processes prevailing through this section enhances porosity through dissolution (intercrystalline and vuggy porosity) with respect to the porosity of the original limestone facies .…”

Section: Fa4mentioning

confidence: 97%

Geophysical Characterization of a Carbonate Platform Reservoir Based on Outcrop Analogue Study (Onshore, Lebanon)

Abbani

Adelinet²,

Inati

et al. 2022

83rd EAGE Annual Conference &Amp; Exhibition

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The end of thesis is a privileged moment to thank all the people who encouraged me and supported me to achieve this work. I would like to express my thanks to my supervisors, Ms.Mathilde Adelinet and Ms. Lama Inati. Thank you for your guidance and advice throughout this thesis project. Your efforts have been essential in guiding me and providing me with the knowledge and skills needed to complete this research, as well as to mitigating the difficulties tackled during my project. I sincerely thank you for your support that made these years enjoyable and successful. I would like to thank Mr. François Fournier and Mr. Yves Géraud as well for the time devoted to evaluating this thesis work as reviewers. I wish also to thank Mr. Jérôme Fortin, Mr. Ludovic Bodet, and Ms. Laetitia Le Pourhiet for having accepted to be the examiners of this thesis.I would like to express special thanks for Mr. Fadi Nader for contributing to this work, especially during the field work conducted at the beginning of this thesis project. The knowledge and experience he shared, as well as his comments throughout this project have indeed contributed to making this work successful. I would also like to thank Mr. Cédric Bailly for his contribution to this project, especially in the field work and the petrophysical laboratory measurements.My thanks also go to the Lebanese Petroleum Administration (LPA), for Mr. Wissam Chbat -

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High resolution cathodoluminescence spectroscopy of carbonate cementation in Khurmala Formation (Paleocene–L. Eocene) from Iraqi Kurdistan Region, Northern Iraq

Cited by 9 publications

References 36 publications

Genesis and soil environmental implications of intact in-situ rhizoliths in dunes of the Badain Jaran Desert, northwestern China

Genesis and soil environmental implications of intact in-situ rhizoliths in dunes of the Badain Jaran Desert, northwestern China

Seepage reflux dolomitization and telogenetic karstification in Majiagou Formation in the Ordos Basin, China

Geophysical Characterization of a Carbonate Platform Reservoir Based on Outcrop Analogue Study (Onshore, Lebanon)

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