Meinhold, Guido

[["dc.bibliographiccitation.artnumber","62"],["dc.bibliographiccitation.issue","1"],["dc.bibliographiccitation.journal","ARABIAN JOURNAL OF GEOSCIENCES"],["dc.bibliographiccitation.volume","9"],["dc.contributor.author","Meinhold, Guido"],["dc.contributor.author","Le Heron, Daniel Paul"],["dc.contributor.author","Elgadry, Mohamed"],["dc.contributor.author","Abutarruma, Yousef"],["dc.date.accessioned","2018-11-07T10:21:05Z"],["dc.date.available","2018-11-07T10:21:05Z"],["dc.date.issued","2016"],["dc.description.abstract","Across the Saharan platform, mudrocks of latest Ordovician-Silurian age (the Tanezzuft Formation) are a major source rock interval for Palaeozoic petroleum systems, but source rock quality is variable and difficult to predict. In the Kufra Basin of southern Libya, evidence for organic enrichment in this formation is scarce. This paper presents the results of a spectral gamma-ray study of siliciclastic sedimentary rocks in Jabal Eghei at the western margin of the basin. The study spans the Ordovician-Silurian interval together with overlying Mesozoic strata and was conducted at outcrop using a hand-held gamma-ray spectrometer. Element concentrations of potassium (K), uranium (U) and thorium (Th) were collected from mudrock and sandstone successions to identify natural background values of these elements for different formations. Uranium contents were used to identify possible 'hot shales' with source rock potential. This study shows that sandstones and mudrocks are clearly discriminated by their K, U and Th contents. Most sandstones have <0.3 % of K, <4 ppm of U and <10 ppm of Th. In contrast, the mudrocks show values of >0.3 % of K, >4 ppm of U and >10 ppm of Th. Based on gamma-ray spectrometry, the Tanezzuft Formation is divisible into lower, middle and upper members. There is a significant difference in K content between the three members. Exposures of the lower member show K contents less than 0.5 %; those from the middle member are between 1.5 and 3.6 %; and the upper member has K contents between 0.5 and 1.5 %. Notably, U values >10 ppm are restricted to the upper member, indicating the presence of 'warm shales' in Jabal Eghei. There is a progressive increase of Th/K ratios from the basal part of the Tanezzuft Formation towards the upper member. The decrease in K content and increase in Th/K ratios between the middle and the upper members of the Tanezzuft Formation can be explained by a mineralogical change, confirmed by x-ray diffraction analyses on representative samples. The total volume of clay minerals is 64 % higher in the upper member than in the middle member, with kaolinite predominant. These changes in composition suggest a change towards a more weathered sediment source, which was probably caused by increased continental weathering due to climate change from icehouse to greenhouse conditions at the Ordovician-Silurian transition."],["dc.identifier.doi","10.1007/s12517-015-2173-0"],["dc.identifier.isi","000369322200062"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/42020"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Springer"],["dc.publisher.place","Heidelberg"],["dc.relation.issn","1866-7538"],["dc.relation.issn","1866-7511"],["dc.title","The search for 'hot shales' in the western Kufra Basin, Libya: geochemical and mineralogical characterisation of outcrops, and insights into latest Ordovician climate"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","308"],["dc.bibliographiccitation.issue","4"],["dc.bibliographiccitation.journal","Journal of African Earth Sciences"],["dc.bibliographiccitation.lastpage","330"],["dc.bibliographiccitation.volume","61"],["dc.contributor.author","Morton, Andrew C."],["dc.contributor.author","Meinhold, Guido"],["dc.contributor.author","Howard, James P."],["dc.contributor.author","Phillips, Richard J."],["dc.contributor.author","Strogen, Dominic"],["dc.contributor.author","Abutarruma, Yousef"],["dc.contributor.author","Elgadry, Mohamed"],["dc.contributor.author","Thusu, Bindra"],["dc.contributor.author","Whitham, Andrew G."],["dc.date.accessioned","2018-11-07T08:50:05Z"],["dc.date.available","2018-11-07T08:50:05Z"],["dc.date.issued","2011"],["dc.description.abstract","This paper presents the results of an integrated heavy mineral and mineral chemical study of Precambrian-Mesozoic clastic sediments from the eastern Murzuq Basin. The purpose of this study was to constrain the provenance of sediment and to assess the value of heavy minerals as a stratigraphic tool. Conventional heavy mineral analysis was carried out on 64 samples, tourmaline geochemical analysis on 25 samples, garnet geochemical analysis on four samples, rutile geochemical analysis on 21 samples, and clinopyroxene geochemical analysis on two samples. The study indicates that heavy mineral analysis is a valuable tool for understanding the provenance of Palaeozoic and Mesozoic clastic sediments in Libya, despite the intense weathering that surface samples have undergone. Based on heavy mineral ratios and mineral chemical data, there appear to be three key events when the provenance signature changed within the Palaeozoic-Mesozoic sedimentary succession at the eastern Murzuq Basin: (i) at the base of the Tanezzuft Formation (early Silurian), (ii) at the base of the Tadrart Formation (Early Devonian), and (iii) at the base of the Mrar Formation (Carboniferous), subdividing the succession into four intervals (Hasawnah-Mamuniyat, Tanezzuft-Akakus, Tadrart-Awaynat Wanin, and Mrar-Nubian). There is probably also an event between the Precambrian and the Hasawnah Formation (Cambrian), but there are currently insufficient data to prove this unequivocally. Comparing data of the present study with results from the previous work in the Kufra Basin it is evident that heavy mineral data provide useful evidence for differences in provenance both regionally and stratigraphically in basins of the central Sahara. (C) 2011 Elsevier Ltd. All rights reserved."],["dc.description.sponsorship","consortium of subscribing oil and gas companies"],["dc.identifier.doi","10.1016/j.jafrearsci.2011.08.005"],["dc.identifier.isi","000297891600004"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/21610"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Pergamon-elsevier Science Ltd"],["dc.relation.issn","1464-343X"],["dc.title","A heavy mineral study of sandstones from the eastern Murzuq Basin, Libya: Constraints on provenance and stratigraphic correlation"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","90"],["dc.bibliographiccitation.journal","Review of Palaeobotany and Palynology"],["dc.bibliographiccitation.lastpage","118"],["dc.bibliographiccitation.volume","197"],["dc.contributor.author","Thusu, Bindra"],["dc.contributor.author","Rasul, Syed"],["dc.contributor.author","Paris, Florentin"],["dc.contributor.author","Meinhold, Guido"],["dc.contributor.author","Howard, James P."],["dc.contributor.author","Abutarruma, Yousef"],["dc.contributor.author","Whitham, Andrew G."],["dc.date.accessioned","2018-11-07T09:18:39Z"],["dc.date.available","2018-11-07T09:18:39Z"],["dc.date.issued","2013"],["dc.description.abstract","Latest Ordovician-earliest Silurian Tanezzuft Formation shales recovered from core material of the shallow bore-hole JA-2 drilled in Jebel Asba at the eastern margin of the Kufra Basin, southeastern Libya, yielded well-diversified palynomorph assemblages with transparent and brownish to yellowish vesicles and organic matter (visual kerogen Types 1 and 2) from depth interval 4620 to 67.82 m. In addition, miospores including cryptospores, and Tasmanites sp. (\"Tasmanites with nodules\"), scolecodonts, and a stratigraphically significant palaeo-marker, the enigmatic, tubular organic structure Tortotubus protuberans, were also recorded frequently in most samples. Kerogen colour based on miospores (TAI <3) and chitinozoan reflectance indicate an immature facies for oil generation. The two uppermost samples (from 3333 m and 46.20 m depths) and the lowermost ones (from 67.92 to 7321 m depth) contain rare palynomorphs and other organic remains and have been partially affected by oxidation. Furthermore, palynological and palynofacies analyses were carried out on cuttings from an old well (UN-REMSA well), ca. 530 m towards the NNE from well JA-2. The composition of the organic residue is similar in both wells. However, the UN-REMSA well yields fairly numerous chitinozoans, scolecodonts and biofilms but lacks the \"thread-like structures\" and \"Tasmanites with nodules\" observed in well JA-2. All the investigated samples in well JA-2 are dominated by a single chitinozoan species, Euconochitina moussegoudaensis Paris (in Le Herisse et al., 2013). Based on correlation with chitinozoan-bearing strata around the Ordovician-Silurian boundary, the analysed samples from well JA-2 and from the UN-REMSA well are regarded as post-glacial, but still of either latest Hirnantian age, or at least no younger than earliest Rhuddanian. A well-diversified acritarch, miospore and cryptospore assemblage recorded in well JA-2 supports a marginal marine (nearshore) depositional environment This assemblage is no older than earliest Rhuddanian yet the latest Hirnantian age of the assemblage cannot be completely ruled out as our current knowledge on the post-glacial, latest Hirnantian acritarch and miospore assemblages is poorly documented in North Africa. (C) 2013 Elsevier B.V. All rights reserved."],["dc.identifier.doi","10.1016/j.revpalbo.2013.05.006"],["dc.identifier.isi","000324359300007"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/28449"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Elsevier Science Bv"],["dc.relation.issn","1879-0615"],["dc.relation.issn","0034-6667"],["dc.title","Latest Ordovician-earliest Silurian acritarchs and chitinozoans from subsurface samples in Jebel Asba, Kufra Basin, SE Libya"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","105"],["dc.bibliographiccitation.issue","2"],["dc.bibliographiccitation.journal","Journal of Petroleum Geology"],["dc.bibliographiccitation.lastpage","115"],["dc.bibliographiccitation.volume","36"],["dc.contributor.author","Meinhold, Guido"],["dc.contributor.author","Whitham, Andrew G."],["dc.contributor.author","Howard, J. P."],["dc.contributor.author","Stewart, J. C."],["dc.contributor.author","Abutarruma, Yousef"],["dc.contributor.author","Thusu, Bindra"],["dc.date.accessioned","2018-11-07T09:26:14Z"],["dc.date.available","2018-11-07T09:26:14Z"],["dc.date.issued","2013"],["dc.description.abstract","This paper summarizes the results of Rock-Eval pyrolysis data of 43 shale samples collected from the latest Ordovician - earliest Silurian (Tanezzuft Formation) interval in the CASP JA-2 well at Jebel Asba on the eastern margin of the Kufra Basin, SE Libya. The results are supported by analysis of cuttings samples from an earlier well of uncertain origin nearby, referred to here as the UN-REMSA well. The Tanezzuft Formation succession encountered in the JA-2 well can be divided into three intervals based on Rock-Eval pyrolysis data. Shales in the shallowest interval (20 - 46.5 m depth) are altered probably by weathering and lack significant amounts of organic matter. Total organic carbon (TOC) contents of shales from the intermediate interval (46.5 - 68.5 m depth) vary between 0.19 and 0.75 wt%. Most samples in this interval have very limited source rock potential although a few have Hydrogen Index (HI) values up to 378 mg S-2/g TOC.T-max values of 422 - 426 degrees C indicate the organic matter is immature. Shales from the deepest interval (68.5 - 73.9 m depth) are diagenetically altered, perhaps by fluids flowing along a nearby fault or along the contact between the Tanezzuft Formation and the underlying Mamuniyat Formation and apparently lack any organic matter. Cuttings samples from the UN-REMSA well have TOC contents of 0.48-0.87 wt%, HI values of 242-252 mg S-2/g TOC, and T-max values of 421-425 degrees C. These results offer little support for the presence of the basal Silurian (Tanezzuft Formation) source rock which is prolific elsewhere in SW Libya and eastern Algeria and, together with the overall immaturity of the equivalent section, reduces the probability of finding major oil reserves in the eastern part of the Kufra Basin."],["dc.description.sponsorship","consortium of oil and gas industry subscribers"],["dc.identifier.doi","10.1111/jpg.12546"],["dc.identifier.isi","000320644900001"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/30254"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Wiley-blackwell"],["dc.relation.issn","0141-6421"],["dc.relation.issn","0141-6421"],["dc.title","HYDROCARBON SOURCE ROCK POTENTIAL OF LATEST ORDOVICIAN - EARLIEST SILURIAN TANEZZUFT FORMATION SHALES FROM THE EASTERN KUFRA BASIN, SE LIBYA"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","224"],["dc.bibliographiccitation.journal","Marine and Petroleum Geology"],["dc.bibliographiccitation.lastpage","246"],["dc.bibliographiccitation.volume","48"],["dc.contributor.author","Meinhold, Guido"],["dc.contributor.author","Howard, James P."],["dc.contributor.author","Strogen, Dominic"],["dc.contributor.author","Kaye, Matthew D."],["dc.contributor.author","Abutarruma, Yousef"],["dc.contributor.author","Elgadry, Mohamed"],["dc.contributor.author","Thusu, Bindra"],["dc.contributor.author","Whitham, Andrew G."],["dc.date.accessioned","2018-11-07T09:17:08Z"],["dc.date.available","2018-11-07T09:17:08Z"],["dc.date.issued","2013"],["dc.description.abstract","A shallow borehole was drilled in lower Silurian (Rhuddanian lower Aeronian) Tanezzuft Formation siliciclastic sediments at the eastern margin of the Murzuq Basin. Shale samples were retrieved from the borehole to study their source rock potential and trace element geochemical composition. Thirty shale samples analysed from borehole CDEG-2a reveal three geochemically distinct intervals. Shales from the top (23-38 m) interval are weathered and have negligible organic content. Shales from the middle (38-42 m) interval have moderate to good organic richness (0.6-1.7 wt.% TOC) with Hydrogen Index (HI) values up to 443 mg S2/g TOC. Shales from the bottom (42-51 m) interval have poor to moderate organic richness (0.07-0.8 wt.% TOC) with HI values up to 277 mg S2/g TOC. All samples have limited source rock potential and are immature to early mature for hydrocarbon generation. It is unlikely that they have ever been buried deeper than similar to 2 km. Low TOC values (< 2 wt.%) together with low concentrations of uranium (< 10 ppm) indicate the absence of organic-rich black shale ('hot shale') source rocks in the studied interval. Inorganic geochemical redox proxies (Ce-anomaly, authigenic U, Th/U, V/Cr, Ni/Co, and V/Sc) indicate that the lower Silurian Tanezzuft Formation shales from borehole CDEG-2a were deposited under oxic bottom waters, explaining their relatively low TOC values. Deposition took place in a shallow marine environment, in a proximal position with regard to an early Silurian palaeo-shoreline. This combined Rock-Eval pyrolysis and whole-rock geochemical study provides new insights into the Silurian source rock distribution and hydrocarbon prospectivity in central North Africa. (c) 2013 Elsevier Ltd. All rights reserved."],["dc.identifier.doi","10.1016/j.marpetgeo.2013.08.010"],["dc.identifier.isi","000328095100019"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/28092"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Elsevier Sci Ltd"],["dc.relation.issn","1873-4073"],["dc.relation.issn","0264-8172"],["dc.title","Hydrocarbon source rock potential and elemental composition of lower Silurian subsurface shales of the eastern Murzuq Basin, southern Libya"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","1"],["dc.bibliographiccitation.journal","Review of Palaeobotany and Palynology"],["dc.bibliographiccitation.lastpage","26"],["dc.bibliographiccitation.volume","174"],["dc.contributor.author","Paris, Florentin"],["dc.contributor.author","Thusu, Bindra"],["dc.contributor.author","Rasul, Syed"],["dc.contributor.author","Meinhold, Guido"],["dc.contributor.author","Strogen, Dominic"],["dc.contributor.author","Howard, James P."],["dc.contributor.author","Abutarruma, Yousef"],["dc.contributor.author","Elgadry, Mohamed"],["dc.contributor.author","Whitham, Andrew G."],["dc.date.accessioned","2018-11-07T09:11:08Z"],["dc.date.available","2018-11-07T09:11:08Z"],["dc.date.issued","2012"],["dc.description.abstract","This work presents palynological and palynofacies analyses from early Silurian Tanezzuft Formation shales recovered from core material of borehole CDEG-2a drilled in Dor el Gussa at the eastern margin of the Murzuq Basin, southern Libya. The material has yielded well-diversified palynomorph and chitinozoan assemblages and organic matter from a depth interval of 37.41 to 50.64 m. The interval above 37.41 m is weathered and barren of palynomorphs. The palynomorph assemblage present from the 37.41-50.64 m interval is early Llandovery (Rhuddanian-early Aeronian) in age and was deposited in a shallow, open marine (but proximal) environment with a minor landward shift between 43.02 and 46.13 m. The oldest chitinozoan assemblage recorded in the studied core samples can be referred to the fragilis regional Biozone. However, because the relative abundance of Spinachitina fragilis is low, it is considered here that the deepest part of the borehole (at 50.64 m) does not penetrate the actual base of the Rhuddanian. Thus, a Rhuddanian-earliest Aeronian age is retained here for the corresponding strata in borehole CDEG-2a. The core includes the boundary between the fragilis and nuayyimensis biozones, which was until now unknown from southern Libya. Furthermore, we describe a new chitinozoan species, Angochitina murzukensis sp. nov. The intervals 37.41-42.36 m and 46.48-50.64 m show a dominance of amorphous organic matter (AOM) Types 1 and 2, suggesting an oil-prone potential, in contrast to interval 43.02-46.13 m, which is dominated by land-derived (vitrinite) Type 3 suggesting a gas-prone potential. The Ordovician-Silurian boundary and therefore the glacial-related Late Ordovician deposits have not been penetrated by the borehole. In all likelihood, this boundary is not far below the bottom of borehole CDEG-2a. (C) 2012 Elsevier B.V. All rights reserved."],["dc.description.sponsorship","consortium of oil and gas industry"],["dc.identifier.doi","10.1016/j.revpalbo.2012.02.002"],["dc.identifier.isi","000303185600001"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/26655"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Elsevier Science Bv"],["dc.relation.issn","0034-6667"],["dc.title","Palynological and palynofacies analysis of early Silurian shales from borehole CDEG-2a in Dor el Gussa, eastern Murzuq Basin, Libya"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.artnumber","S1464343X2100279X"],["dc.bibliographiccitation.firstpage","104378"],["dc.bibliographiccitation.journal","Journal of African Earth Sciences"],["dc.bibliographiccitation.volume","184"],["dc.contributor.author","Meinhold, Guido"],["dc.contributor.author","Howard, James"],["dc.contributor.author","Abutarruma, Yousef"],["dc.contributor.author","Thusu, Bindra"],["dc.contributor.author","Whitham, Andrew G."],["dc.date.accessioned","2021-12-01T09:24:12Z"],["dc.date.available","2021-12-01T09:24:12Z"],["dc.date.issued","2021"],["dc.identifier.doi","10.1016/j.jafrearsci.2021.104378"],["dc.identifier.pii","S1464343X2100279X"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/94880"],["dc.language.iso","en"],["dc.notes.intern","DOI-Import GROB-478"],["dc.relation.issn","1464-343X"],["dc.title","Mineralogical and geochemical changes in subsurface shales straddling the Ordovician–Silurian boundary in the eastern Kufra Basin, Libya"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dspace.entity.type","Publication"]]