干旱区生态环境知识资源中心(Arid): Mineralogical and geochemical characteristics of the Paleozoic source rocks, Akkas gas field, Western Desert of Iraq: Implications for their origin, maturation and Ordovician-Silurian transition

Arid

DOI	10.1016/j.marpetgeo.2020.104432
	Mineralogical and geochemical characteristics of the Paleozoic source rocks, Akkas gas field, Western Desert of Iraq: Implications for their origin, maturation and Ordovician-Silurian transition
	Mohammed, Ibrahim Q.; Farouk, Sherif; Baioumy, Hassan; Lotfy, Naira Magdy; Al-Hadidy, Aboosh Hussain
通讯作者	Farouk, S
来源期刊	MARINE AND PETROLEUM GEOLOGY
ISSN	0264-8172
EISSN	1873-4073
出版年	2020
卷号	118
英文摘要	Ordovician-Silurian black shales are the source rocks in the Palaeozoic petroleum system in Iraq. However, their source and depositional conditions from their mineralogy and inorganic geochemistry are quite lacking in previous works. These shales also provide an opportunity to examine the changes in paleoenvironment, paleoclimate and paleoredox conditions across the Ordovician-Silurian transition. The Ordovician black shales comprise of kaolinite, illite, chlorite, quartz, dolomite, calcite, and traces of feldspars and siderite, while the Silurian black shales comprise of illite, quartz, calcite, dolomite and pyrite. Calculated SiO2 (wt %) and Al2O3/TiO2 ratios suggest felsic source rocks for the Ordovician black shales and intermediate source rocks for Silurian hot shales. The shallow marine setting for the Ordovician black shales that changed to a deeper environment during the Silurian time was interpreted from the V, P2O5, and Al2O3 diagrams is consistent with the abundance of trace fossils Monocraterion sp., Cruziana problematica, Diplichnites sp., and Skolithos sp. which refer to proximal shallow marine conditions and abundance of graptolites monograptus in the Silurian black shales, which refer to an open-marine environment. Paleoredox indicators such as TOC and Mn contents as well as Ni/Co, V/Ni, U/Th, and V/Cr ratios prove fluctuation of redox conditions from oxic in the Ordovician shales to anoxic in the Silurian black shales. Late Ordovician glaciation in Iraq can be indicated from the low values of chemical index of weathering (CIA = 52-58) in the samples from the upper part of the upper part of the Khabour Formation that refer to cold and arid climate conditions that prevailed during the late Ordovician time. Abundance of extrabasinal and poor-sorted mud clasts in this interval might support the glaciogenic origin of this part. The black shales in the Khabour Formation is considered as fair source rock (average TOC = 0.9 wt%), while that in the Akkas Formation is an excellent source rock (average TOC = 13.2 wt%) for hydrocarbon generation. Kerogen in the Ordovician and Silurian black shales were derived from marine organic matter as indicated by the binary plot and total C1-C15-n-C6-n-C14-n-C15 + ternary diagram. Organic matter in the Ordovician black shales is highly matured compared to that in the Silurian black shales due to higher illite crystallinity (IC) values in the Ordovician (0.61-0.75 degrees D2 theta) relative to that in the Silurian (0.45-0.55 degrees D2 theta) black shales.
英文关键词	Black shales Iraq Origin Organic matter Ordovician-silurian transition Glaciation Maturation
类型	Article
语种	英语
收录类别	SCI-E
WOS记录号	WOS:000537736900029
WOS关键词	MARINE BLACK SHALES ; SEDIMENTARY-ROCKS ; TRACE-ELEMENTS ; YANGTZE PLATFORM ; CHINA ; ENVIRONMENTS ; STRATIGRAPHY ; ENRICHMENT ; DEPOSITION ; SEQUENCE
WOS类目	Geosciences, Multidisciplinary
WOS研究方向	Geology
资源类型	期刊论文
条目标识符	http://119.78.100.177/qdio/handle/2XILL650/324633
作者单位	[Mohammed, Ibrahim Q.] Iraqi Geol Survey, Erbil, Iraq; [Farouk, Sherif; Lotfy, Naira Magdy] Egyptian Petr Res Inst, 1 Ahmed El Zomor St, Cairo, Egypt; [Baioumy, Hassan] Cent Met R&D Inst, POB 87, Cairo, Egypt; [Al-Hadidy, Aboosh Hussain] Immam Jafar Alsaq Univ, Baghdad, Iraq
推荐引用方式 GB/T 7714	Mohammed, Ibrahim Q.,Farouk, Sherif,Baioumy, Hassan,et al. Mineralogical and geochemical characteristics of the Paleozoic source rocks, Akkas gas field, Western Desert of Iraq: Implications for their origin, maturation and Ordovician-Silurian transition[J],2020,118.
APA	Mohammed, Ibrahim Q.,Farouk, Sherif,Baioumy, Hassan,Lotfy, Naira Magdy,&Al-Hadidy, Aboosh Hussain.(2020).Mineralogical and geochemical characteristics of the Paleozoic source rocks, Akkas gas field, Western Desert of Iraq: Implications for their origin, maturation and Ordovician-Silurian transition.MARINE AND PETROLEUM GEOLOGY,118.
MLA	Mohammed, Ibrahim Q.,et al."Mineralogical and geochemical characteristics of the Paleozoic source rocks, Akkas gas field, Western Desert of Iraq: Implications for their origin, maturation and Ordovician-Silurian transition".MARINE AND PETROLEUM GEOLOGY 118(2020).