Recurring Patterns of Sea Level Changes within a Palynological-Based Sequence Stratigraphy Framework of the Middle Jurassic Organic Matter-Rich Khatatba Formation, Egypt
The Middle Jurassic was a time of marginal to shallow shelf settings dominated by organic matter-rich deposition in northern Egypt, southern Tethys. Paleoenvironmental and sequence stratigraphic reconstructions are of paramount significance for a better understanding of basin history and related res...
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MDPI AG
2023-06-01
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| Online Access: | https://www.mdpi.com/2075-163X/13/6/827 |
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| author | Ahmed Mansour Sameh S. Tahoun Aya Raafat Mohamed S. Ahmed Thomas Gentzis |
| author_facet | Ahmed Mansour Sameh S. Tahoun Aya Raafat Mohamed S. Ahmed Thomas Gentzis |
| author_sort | Ahmed Mansour |
| collection | DOAJ |
| description | The Middle Jurassic was a time of marginal to shallow shelf settings dominated by organic matter-rich deposition in northern Egypt, southern Tethys. Paleoenvironmental and sequence stratigraphic reconstructions are of paramount significance for a better understanding of basin history and related reservoirs and source rock units. For this purpose, a detailed palynomorph and palynofacies analysis of the Middle Jurassic Khatatba Formation in the Dahab-Mireir Basin, north Western Desert, was conducted. A moderately to well-preserved, moderately diverse palynomorph assemblage of spores, pollen, and dinoflagellate cysts is identified. Marker dinoflagellate cysts, including <i>Dichadogonyaulax sellwoodii</i>, <i>Escharisphaeridia pocokii</i>, <i>Gonyaulacysta adecta</i>, <i>Korystocysta gochtii</i>, <i>Pareodinia ceratophora</i>, and <i>Wanaea acollaris</i>, defined a Bajocian to Callovian age. Palynofacies analysis of the Khatatba Formation revealed two assemblages, whereby PFA-1 is the most abundant in the study well and is comprised mainly of terrestrial phytoclasts deposited nearby fluvio-deltaic sources. The infrequently reported PFA-2 consists of moderate abundances of phytoclasts and AOM, deposited in an inner shelf environment. A more reliable paleoenvironmental interpretation was indicated based on three palynomorph assemblages. The spore-dominated assemblage indicated deposition in a deltaic environment, while the mixed palynomorph assemblage revealed fluvio-deltaic to marginal shallow marine conditions. The microplankton-dominated assemblage is represented by minor samples and reflects an offshore inner shelf condition. Furthermore, the Middle Jurassic relative sea level was reconstructed based on the quantitative variations in the terrestrial/marine (T:M) ratios and abundances of spores, pollen, and dinoflagellate cysts. This led to the subdivide of the Khatatba Formation into thirteen third-order transgressive-regressive sequences, which can be correlated with the global Jurassic short-term sea level changes. Active tectonics and accelerated drifting of the Eurasian Plate during the Middle Jurassic are suggested to control basin uplift/subsidence and, therefore, recurring patterns of relative sea level change. |
| first_indexed | 2024-03-11T02:07:27Z |
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| issn | 2075-163X |
| language | English |
| last_indexed | 2024-03-11T02:07:27Z |
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| spelling | doaj.art-8a4944cf3ea84664994438093131b1f42023-11-18T11:46:05ZengMDPI AGMinerals2075-163X2023-06-0113682710.3390/min13060827Recurring Patterns of Sea Level Changes within a Palynological-Based Sequence Stratigraphy Framework of the Middle Jurassic Organic Matter-Rich Khatatba Formation, EgyptAhmed Mansour0Sameh S. Tahoun1Aya Raafat2Mohamed S. Ahmed3Thomas Gentzis4School of Geoscience and Technology, Southwest Petroleum University, Chengdu 610500, ChinaGeology Department, Faculty of Science, Cairo University, Giza 12613, EgyptGeology Department, Faculty of Science, Cairo University, Giza 12613, EgyptGeology and Geophysics Department, College of Science, King Saud University, P.O. Box 2455, Riyadh 11451, Saudi ArabiaCore Laboratories, Houston, TX 77040, USAThe Middle Jurassic was a time of marginal to shallow shelf settings dominated by organic matter-rich deposition in northern Egypt, southern Tethys. Paleoenvironmental and sequence stratigraphic reconstructions are of paramount significance for a better understanding of basin history and related reservoirs and source rock units. For this purpose, a detailed palynomorph and palynofacies analysis of the Middle Jurassic Khatatba Formation in the Dahab-Mireir Basin, north Western Desert, was conducted. A moderately to well-preserved, moderately diverse palynomorph assemblage of spores, pollen, and dinoflagellate cysts is identified. Marker dinoflagellate cysts, including <i>Dichadogonyaulax sellwoodii</i>, <i>Escharisphaeridia pocokii</i>, <i>Gonyaulacysta adecta</i>, <i>Korystocysta gochtii</i>, <i>Pareodinia ceratophora</i>, and <i>Wanaea acollaris</i>, defined a Bajocian to Callovian age. Palynofacies analysis of the Khatatba Formation revealed two assemblages, whereby PFA-1 is the most abundant in the study well and is comprised mainly of terrestrial phytoclasts deposited nearby fluvio-deltaic sources. The infrequently reported PFA-2 consists of moderate abundances of phytoclasts and AOM, deposited in an inner shelf environment. A more reliable paleoenvironmental interpretation was indicated based on three palynomorph assemblages. The spore-dominated assemblage indicated deposition in a deltaic environment, while the mixed palynomorph assemblage revealed fluvio-deltaic to marginal shallow marine conditions. The microplankton-dominated assemblage is represented by minor samples and reflects an offshore inner shelf condition. Furthermore, the Middle Jurassic relative sea level was reconstructed based on the quantitative variations in the terrestrial/marine (T:M) ratios and abundances of spores, pollen, and dinoflagellate cysts. This led to the subdivide of the Khatatba Formation into thirteen third-order transgressive-regressive sequences, which can be correlated with the global Jurassic short-term sea level changes. Active tectonics and accelerated drifting of the Eurasian Plate during the Middle Jurassic are suggested to control basin uplift/subsidence and, therefore, recurring patterns of relative sea level change.https://www.mdpi.com/2075-163X/13/6/827dinoflagellate cyststransgression-regression cyclesBajocianBathonian–CallovianDahab-Mireir Basinnorth Western Desert |
| spellingShingle | Ahmed Mansour Sameh S. Tahoun Aya Raafat Mohamed S. Ahmed Thomas Gentzis Recurring Patterns of Sea Level Changes within a Palynological-Based Sequence Stratigraphy Framework of the Middle Jurassic Organic Matter-Rich Khatatba Formation, Egypt Minerals dinoflagellate cysts transgression-regression cycles Bajocian Bathonian–Callovian Dahab-Mireir Basin north Western Desert |
| title | Recurring Patterns of Sea Level Changes within a Palynological-Based Sequence Stratigraphy Framework of the Middle Jurassic Organic Matter-Rich Khatatba Formation, Egypt |
| title_full | Recurring Patterns of Sea Level Changes within a Palynological-Based Sequence Stratigraphy Framework of the Middle Jurassic Organic Matter-Rich Khatatba Formation, Egypt |
| title_fullStr | Recurring Patterns of Sea Level Changes within a Palynological-Based Sequence Stratigraphy Framework of the Middle Jurassic Organic Matter-Rich Khatatba Formation, Egypt |
| title_full_unstemmed | Recurring Patterns of Sea Level Changes within a Palynological-Based Sequence Stratigraphy Framework of the Middle Jurassic Organic Matter-Rich Khatatba Formation, Egypt |
| title_short | Recurring Patterns of Sea Level Changes within a Palynological-Based Sequence Stratigraphy Framework of the Middle Jurassic Organic Matter-Rich Khatatba Formation, Egypt |
| title_sort | recurring patterns of sea level changes within a palynological based sequence stratigraphy framework of the middle jurassic organic matter rich khatatba formation egypt |
| topic | dinoflagellate cysts transgression-regression cycles Bajocian Bathonian–Callovian Dahab-Mireir Basin north Western Desert |
| url | https://www.mdpi.com/2075-163X/13/6/827 |
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