Muwaqqar Chalk Marl Research Articles

Upper Cretaceous-Paleocene Unconventional Oil Shales in Egypt and Jordan: Insights into Organic Geochemistry

The present paper investigates the unconventional hydrocarbon potential and characteristics of Campanian–Paleocene oil shales at five outcrop sections in central Egypt and Jordan. One-hundred and seven outcrop samples were analyzed for their content of total organic carbon and total sulfur. Twenty-four samples were selected for further geochemical treatment, including Rock-Eval pyrolysis, and six samples were subjected to molecular analyses using gas Chromatography (GC) and Gas Chromatography-Mass Spectrometry (GC-MS). The distribution of aliphatic hydrocarbon biomarkers indicated that most of the organic matter in the studied samples had a marine origin under anoxic to suboxic conditions. The results indicated that the upper Campanian Duwi Formation in the Quseir area of central Egypt and the Maastrichtian-Paleocene Muwaqqar Chalk Marl (MCM) Formation in the Lajjun area of central Jordan had a relatively high hydrocarbon generating potential with a TOC content of up to 20%wt of immature Type I/II kerogen. Biomarker studies of the investigated formations revealed that the origin of the organic matter is marine algae with a minor contribution of bacterial biomass. The terrigenous/aquatic ratio (TAR) indicated the marine origin of the Jordanian organic matter (MCM and Al-Hisa Phosphorite Formation formations). By contrast, the Duwi Formation in Egypt and the Amman silicified limestone Formation in the Umm Qais section of Jordan showed that these localities were affected by a more terrigenous influx to the principal marine organic matter compared with other rock units. In addition, in the Abu Tartur section the Duwi Formation showed a significant microbial reworking of organic matter reducing the actual amount of organic matter and its hydrocarbon generating potentiality. Clear correlations between nature and the preservation of organic matter is noticed, where the high organic matter mainly occurs in regional paleo-upwelling areas, strongly related to an increase in marine phytoplanktonic/algal and bacterial productivity.

Geochemical characteristics of carbonaceous chalk near the Cretaceous/Paleogene transition, central Jordan: Strong metal enrichment of redox-sensitive and biophile elements from remineralized calcitic plankton

Carbonaceous calcitic chalk from a 50-m stratigraphic section of the Maastrichtian-Danian Muwaqqar Chalk Marl (MCM) Formation, Jordan, has elevated concentrations of biophile and/or redox-sensitive trace metals (Mo, Ni, V, U, Cr, Cd, Ag, Se, and P) which indicate enhanced paleo-bioproductivity, biodegradation and remineralization under reducing conditions. Very low concentrations in Mn and Ba suggest a relatively open system for components mobile under reducing conditions. The last 800,000 years to the K/Pg boundary are not exposed in Jordan, but the stratigraphic 20-m-interval below and above the hiatus of the K/Pg transition (n = 8) with 2.6 ± 1.8 wt% organic C is particularly metal-enriched with average bulk-rock contents of 132 ppm Mo, 177 ppm Ni, 363 ppm V, 576 ppm Zn, 39 ppm Se, 1.4 ppm Ag, 106 ppm Cd, 474 ppm Cr. These concentrations are dominantly of authigenous origin, when normalized to PAAS, i.e. 100 % Mo, 100% Ag, 100% Cd, 96% Cr, 95% Ni, 95% Zn, 80% V authigenous, and testify to ≥90% of biodegradation of planktonic debris by anaerobic bacterial activity at or near the seafloor. The depositional environment is euxinic, and Mo/TOC ratios from <10 to around 100 (as well as analogous trends for Ni/TOC and Cr/TOC) indicate an evolution from initially restricted hydrographic conditions to unrestricted open-sea conditions towards the K/Pg transition. The common paleoenvironmental proxies for black shale such as V, V/(V + Ni) and V/Cr ratios, indicate oxic depositional conditions for the studied chalk, which are misleading because the low illite content in the calcareous ooze does not allow sufficient retention of V in this chalk. REE patterns identify a seawater and a clastic component to about equal amounts on average, with authigenous ΣREE of 23 ± 19 ppm (n = 20). The negative Ce anomaly of the authigenous component is −0.6 ± 0.2 (log PAAS normalized), compared to recent seawater with −1.1. The geochemical composition of the carbonaceous calcitic chalk sequence is an expression of the general Cretaceous-Paleogene upwelling regime on the southern passive margin of the Neo-Tethys Ocean in the Cretaceous-Palaeogene (K-Pg) greenhouse environment.

Geochemistry and stable isotopes of the upper Campanian–lower Maastrichtian phosphorite‐bearing sequence, Central Jordan: Implications for their age, origin, and diagenesis

Three major lithofacies have been described in Lajjun area, central Jordan, including the phosphorite and intercalated limestone of the Al‐Hisa Phosphorite Formation, as well as the Muwaqqar Chalk Marl Formation. 87Sr/86Sr isotopic data indicate a late Campanian age for the Al‐Hisa Phosphorite Formation, whereas the overlying chalk of the Muwaqqar Formation contains the lowest Maastrichtian planktic foraminiferal zone of Rugoglobigerina hexacamerata (CF8b).The phosphorites are of reworked origin as inferred from the homogeneous texture with lack of any concentric structure in the phosphatic pellets and the presence of bone fragments inside the phosphatic pellets, which are filled with phosphatic mud similar to the matrix of phosphatic pellet. They still reflect the original seawater rare‐earth pattern, as indicated from the similarity in their rare‐earth element (REE) concentration and patterns with seawater. Positive correlations between P2O5 and Fe2O3, TiO2 and K2O, relatively high rare‐earth contents, and similarity in (Nd/Yb)SN ratio to the modern shallow seawater suggest a continental marginal depositional environment for the limestone and chalk facies. δ13C values are lower and more variable compared with the estimated global range of upper Campanian–lower Maastrichtian δ13C values in shelf and oceanic basins. This indicates a diagenetic effect on the δ13C isotopes and suggests that a significant proportion of carbonate ions could have been resulted from the organic carbon oxidation. Three third‐order depositional sequences matching with the global and regional sea‐level patterns are identified in the studied section based on vertical facies changes. The basal transgressive surface of each sequence is constantly characterized by a phosphatic horizon.

The lithic landscape around Kharaneh IV (Azraq Basin, Jordan): Petrographical and geochemical characterization of geological cherts

As part of a current archaeological project focusing on the Azraq Basin, through notably the excavation of the Early-Middle Epipalaeolithic site of Kharaneh IV, a geoarchaeological analysis was started to ultimately characterize the chert types exploited by the inhabitants of the site and to assess their geographical origins. In order to examine prehistoric lithic procurement strategies, a detailed study of the geological literature and maps of a 3000 km2 area surrounding the site was completed. This study revealed the presence of three chert-bearing formations dated to the Late Cretaceous and Early Tertiary in that territory: Muwaqqar Chalk-Marl Formation, Umm Rijam Chert-Limestone Formation, and Wadi Shallala Chalk Formation. A geo-archaeological survey followed. This survey comprised detailed observations about these silicifications in their sedimentary context and the collection of chert samples in both primary and secondary deposits.This contribution presents the main results of this work. The multiplicity of outcrops and the conditions of embeddedness of the siliceous horizons, on the one hand, and the characteristics of these silicifications (size, shape, quality, etc.), on the other hand, all contribute to illustrate the rich lithic potential of this region. Thus the Kharaneh IV inhabitants had access to a wide range of cherts from which to choose their stone tool kit. Given that the Epipalaeolithic tool kit of the Kharaneh IV inhabitants was based on small size tools, quite small nodules would have been sufficient for these populations to develop their lithic industry, so chert outcrops with both small and large nodules were taken into account in this study. Furthermore we present some observations on the textural, micropalaeontological, petrographical and geochemical characterization of some 104 samples of geological siliceous rocks. Such a dataset will constitute the most reliable reference in the comparison with the archaeological lithic assemblages exhumed at the site.We may already mention that the diversity of chert types documented in the geological reference collection is also present in the archaeological assemblages. Most of these lithic types are thus present in the local environment (<15 km away). Moreover differences in raw material selection, procurement and exploitation are already noticeable between the Early and Middle Epipalaeolithic occupations that will need to be further documented and quantified.

The Geology, Stratigraphy and Structure of Ma’an Area, South

This study focused on the geology, stratigraphy and structure of the Ma'an area at the coordinates: 350 30/350 45 / E 300 00/-300 15/ N. Field and laboratory studies have been carried out with aim to get a better understanding on the main geological features at the study area. Therefore, the importance of this study is due to the fact that Jordan is witnessing an expansion in investment in the extractive and exploration industries, and Ma'an Governorate is considered as a huge reservoir of mineral and industrial rocks that will play an important role on mining industries in Jordan. Rocks like phosphate, limestone, coquina, clay, dolomite, sandstone and different types of aggregates are the main source for many industries in the area.The study area is located at 210 km south of Amman and is covered mainly by sedimentary rocks. This study includes a detailed explanation of the sedimentary rocks covering the whole area, including the Ajloun group which consist the Wadi Sir Limestone Formation, and the Balqa group which consist the following formations: Umm Al-Ghudran, Amman Silisicified Limestone, Al Hisa Phosphorite, Muwaqqar Chalk Marl and Umm Rijam Chert Limestone, as well as the lake sediments which appear in different localities in the study area .The study also includes the most important geological structures, where the most prominent direction of these structures are the north-south, northeast-southwest, northwest and southeast faults, with few folds in different parts of the region. Keywords: Ma’an, sedimentary, formation, lake, structure DOI : 10.7176/JEES/9-3-10 Publication date :March 31 st 2019

Multiple sulfur isotopes (δ34S, Δ33S) of organic sulfur and pyrite from Late Cretaceous to Early Eocene oil shales in Jordan

We present the first multiple sulfur isotope study (32S, 33S, 34S, 36S) of bulk kerogen sulfur (KS) and disulfides (‘chromium-reducible sulfur’, CRS) from the oil shale of the Umm Rijam Chert-Limestone and Muwaqqar Chalk Marl Formation, Jordan (Late Cretaceous to Early Eocene, appr. 50–70 Ma).Analysis of the sulfur isotopic composition of KS (δ34SKS) shows values ranging from 0.3 to 17.9‰, which are 34S-enriched compared to the δ34SCRS ranging from −23.5 to −3.7‰. Values for CRS and KS are significantly 34S-depleted compared to seawater sulfate sulfur which suggests a major input of early-diagenetic, microbially-generated sulfide. A minor contribution of assimilated seawater sulfate to KS is assumed. The 34S-enrichment of KS compared to CRS can be partly explained by (1) sulfide oxidation to intermediate sulfur species prior to its incorporation into organic material, by (2) fractionations during organic sulfur generation, as well as by (3) a post-depositional timing of formation.Additionally, we hypothesize, based on parallel depth trends of maturity parameters (e.g., vitrinite reflectance) and δ34SCRS and δ34SKS values, that the sulfur isotopic compositions were influenced by thermal maturation (catagenesis). We suggest that the CRS pool comprises a contribution of sulfide released during the thermal decomposition of KS.Overall, our study highlights the importance of organic sulfur in sulfur isotopic studies and the potential of multiple sulfur isotope analyses in maturated sedimentary successions.

Benthic Foraminifera and Geochemistry Across the Paleocene–eocene Thermal Maximum Interval in Jordan

AbstractThis study presents benthic foraminiferal data from two sedimentary successions across the Paleocene–Eocene Thermal Maximum (PETM) from Jordan. Calcareous nannofossil biozones NP9a, NP9b, and NP10 of latest Paleocene and earliest Eocene age were encountered in proximal (core OS–01) and distal (core OS–28) sites. Lithologically, the investigated sequence consists of marls, shales, and limestones attributed to the Muwaqqar Chalk-Marl Formation and the Um Rijam Chert Limestone Formation. The δ13Corg curve records the typical carbon isotope excursion (CIE) and shows four distinctive intervals (pre-CIE, CIE-“core”, CIE-“recovery”, post-CIE) over the entire PETM interval in both cores.In the pre-CIE interval, the more proximal site (OS–01) shows high abundances of Neoeponides duwi co-occurring with an outer neritic Midway-type fauna. The fauna indicates meso- to eutrophic conditions in a middle- to outer-neritic setting. The more distal site (OS–28) is characterized by outer-neritic to upper-bathyal taxa (e.g., Cibicides pseudoacutus, Gavelinella beccariiformis, Nuttallides truempyi) suggesting well-ventilated, oligo- to mesotrophic seafloor conditions.The earliest Eocene corresponds to the CIE-“core” interval and is marked by a negative δ13Corg signal, high TOC, low CaCO3 contents, and near absence of benthic foraminifera. Oxygen deficiency in bottom waters with increased organic flux is the most likely scenario to explain the elevated organic content at the seafloor.The subsequent CIE-“recovery” interval of early Eocene age is marked by a restoration of oxygenated seafloor conditions. The proximal site is characterized by a relatively elevated TOC content and high abundance of Lenticulina spp., Valvulineria scrobiculata and common Anomalinoides zitteli, suggesting moderate oxygen conditions and mesotrophic bottom waters. The distal site is characterized by low TOC content and the presence of Lenticulina spp., Valvulineria scrobiculata, Anomalinoides zitteli and Oridorsalis plummerae, indicating a normalization of the organic flux and moderate oxygen concentrations near the seafloor.The post-CIE interval is marked by low TOC content in both cores. Benthic foraminifera include abundant Anomalinoides zitteli and common Lenticulina spp., Valvulineria scrobiculata, Oridorsalis plummerae, Cibicidoides rigidus, Cibicidoides pharaonis, and Anomalinoides praeacutus in the proximal setting. Mesotrophic conditions and a better ventilation of bottom waters are suggested for this interval. Lenticulina spp., Valvulineria scrobiculata, and Oridorsalis plummerae are also associated with the post-CIE interval in the distal site, suggesting similar mesotrophic conditions with renewed oxygenation in bottom waters.

Very early diagenesis in a calcareous, organic-rich mudrock from Jordan

The diagenesis in the organic-rich Cretaceous to Eocene Al Hisa Phosphorite Formation (AHP), Muwaqqar Chalk Marl Formation (MCM) and Umm Rijam Chert-Limestone Formation (URC) formations of Jordan can be linked directly to the fluctuating sedimentary environment of this shelf depositional system in the Middle to Late Eocene, and its influence on the composition of the deposited sediment and the early burial diagenetic environment. Most cementation was early, mostly within the first 10 m of burial, perhaps entirely within the first 100 m of burial. We propose that the siliceous cements are derived from biogenic silica, probably of diatoms, deposited in a shelf of enhanced productivity. Volumetrically, the most important processes were the redistribution of biogenic opal-A (diatoms) and calcite to form pervasive, layered and nodular cements. The formation of the silica and carbonate cements is closely linked through the effects their dissolution and precipitation have on pore fluid chemistry and pH. The chert beds have a biogenic silica origin, formed through replacement of diatoms and radiolaria by opal-CT, and subsequently by quartz. Calcite cement has carbonate derived from microbial diagenesis of organic matter and calcium derived from seawater. The Mg for early dolomite may have been generated by replacement of opal-CT by quartz, ore dissolution of unstable high Mg calcite bioclasts. The silica and carbonate diagenetic processes are both linked to microbial diagenesis of organic matter, and are intimately linked in both time and space, with pH possibly influencing whether a silica or a carbonate mineral precipitates. The paucity of metal cations capable of precipitating as sulphides is crucial to the creation of acidic pore water favourable to silica precipitation, either as opal-CT, chalcedony or quartz. The lack of clay minerals as a sink for the Mg required for opal-CT polymerisation is the principal factor responsible for the remarkably early silica cementation. All the diagenetic processes, with the probable exception of the opal-CT to quartz transition are early, almost certainly within the first 10 m of burial, possibly much less. A paragenetic sequence is presented here based on these two cores that should be tested against a wider core distribution to see whether this diagenetic history can be generalised throughout the basin. Warm bottom water temperatures probably led to silica diagenesis at much shallower burial depths than occurs in many other sedimentary basins. Silicified layers, in turn, commonly host fractures, suggesting that mechanical properties of the strata began to differentiate at a very early stage in the burial cycle. This has wide implications for processes linking diagenesis to deformation.

Ammonite dating of latest Cretaceous mosasaurid reptiles (Squamata, Mosasauroidea) from Jordan—preliminary observations

Jagt, J.W.M., Jagt-Yazykova, E.A., Kaddumi, H.F. & Lindgren, J., April 2017. Ammonite dating of latest Cretaceous mosasaurid reptiles (Squamata, Mosasauroidea) from Jordan—preliminary observations. Alcheringa 42, 587-596. ISSN 0311-5518 Newly collected ammonoid material from the uppermost Cretaceous portion of the Muwaqqar Chalk Marl Formation exposed some 30 km southeast of the Qasr Al’Harrana area (east-central Jordan) includes medium-sized baculitids (Baculites ovatus auctorum, non Say), the sphenodiscid Libycoceras acutodorsatus (Noetling) and the pachydiscids Menuites fresvillensis (Seunes) and Pachydiscus (Pachydiscus) dossantosi (Maury). Of the two last named taxa, the former is a good marker species for the upper Maastrichtian, with records from Europe, central Chile, South India, Baluchistan (Pakistan), Australia, Madagascar and South Africa. The latter is known from the United Arab Emirates/Oman border area, from strata of (late) early to early late Maastrichtian age, as well as from more poorly constrained Maastrichtian levels in Brazil and Nigeria. A comparison with ammonoid assemblages from the Maastrichtian type area (southeast Netherlands/northeast Belgium) suggests correlation of the Muwaqqar Chalk Marl Formation with the middle/upper Maastricht Formation (Emael and Nekum members, ca 66.5–66.1 Ma) and the upper part of the coeval Kunrade Formation. However, associated ‘tegulated’ inoceramids of the Tenuipteria argentea group from the Muwaqqar Chalk Marl Formation favour equivalence with a higher level of the Maastrichtian type area, i.e., the Meerssen Member. From the upper Maastricht Formation and the equivalent upper part of the Kunrade Formation, the following mosasaur genera are currently known: Mosasaurus, Prognathodon, Plioplatecarpus and Carinodens. Interestingly, coeval strata of the Muwaqqar Chalk Marl Formation in east-central Jordan have yielded remains of a largely comparable suite comprising Prognathodon, Mosasaurus, Carinodens and an unnamed, highly derived plioplatecarpine. John W.M. Jagt* [ john.jagt@maastricht.nl ], Natuurhistorisch Museum Maastricht, de Bosquetplein 6–7, 6211 kJ Maastricht, the Netherlands; Elena A. Jagt-Yazykova [ eyazykova@uni.opole.pl ], Opole University, Department of Biosystematics, Oleska 22, 45-052 Opole, Poland; Hani F. Kaddumi [ blossom_trail@yahoo.com ], Eternal River Museum of Natural History, Maroof Al’Rusafi Street, PO Box 11395, Amman 11123, Jordan; Johan Lindgren [ johan.lindgren@geol.lu.se ], Lund University, Department of Geology, Sölvegatan 12, 223 62 Lund, Sweden.

Calcareous sediments of the Muwaqqar Chalk Marl Formation, Jordan: Mineralogical and geochemical evidences for Zn and Cd enrichment

Immature organic-rich siliceous chalk (‘oil shale’) and organic-poor limestones of the Maastrichtian-Paleocene Muwaqqar Chalk Marl Formation (MCM) (central Jordan) deposited on the southern Neo-Tethys epicontinental shelf provide a perfect example of carbonate sedimentation in a bioproductive upwelling environment. The MCM sediments have been studied by XRD, SEM, EMPA, sequential extraction, ICP-MS, GC–MS, and FTIR to gain insights into causes of their unusual composition. The sediments are remarkable by exceptionally high enrichment in phosphorus and redox sensitive elements (RSE), mainly Cd (up to 225ppm), Zn (1500ppm), and Mo (up to 180ppm), as well as in Ni, V, Cr, and U, with a total RSE budget reaching 3200ppm, coupled with up to 23wt% organic matter and 4.3wt% sulphur. The bulk organic matter consists of type I/II kerogens sulphurised during sulphate reduction. Redox sensitive metals were brought to sediments mainly by biogenic shuttle, while the terrestrial input was minor, and hydrothermal fluids apparently did not contribute to total RSE. The metals can reside in sulphide (Zn-Cd-(Cu)) in sphalerite or/and würtzite; Fe-Ni-V-Cu-(Mo) in pyrite, carbonate (Zn-Cd-(Mo-Ni-V)), and organic (Ni-V-Cu) phases. Authigenic Cd-rich sphalerite and würtzite are much more abundant than pyrite in immature ‘oil shales’, for three main reasons: (i) S-bearing ligands coordinating Cd and Zn in primary organic matter; (ii) high sulphur in organic matter; and (iii) low concentrations of reactive iron in bottom sediments. Limestones redeposited under oxic environments lose all sulphides, but high Zn (up to 337ppm) and Cd (up to 29ppm) become redistributed into the newly formed carbonates. Thus, shelf carbonates of different ages deposited under anoxic/sulfidic conditions in zones of high bioproductivity, as well as their derivative limestones and dolomites, can be the primary Zn and Cd storage for Mississippi Valley-type deposits with high Zn/Pb and Cd/Zn ratios.

Characteristics and Genesis of the Groundwater Resources Associated with Oil Shale Deposits in the Azraq and Harrana Basins, Jordan

Upper cretaceous and lower tertiary formations groundwater aquifers are associated with huge reserves of oil shale deposits in Harrana and Azraq Basins are evaluated in terms of water qualities and hydrochemical processes. The oil shale deposits are found within the Muwaqqar Chalk Marl Formation. The Muwaqqar Chalk Marl Formation represents the intermediate formation between the Lower Aquifer Amman Silicified Limestone and the overburden, which represents the overlying Upper Aquifers of Um Rijam Chalk and Wadi Shallala Chalk. This study aimed to improve the understanding of Muwaqqar Chalk Marl Formation as a sealing potential based on water quality and hydrochemical data of the different aquifers. Sixty water samples were collected from Amman Silicified Limestone Aquifer, High Grade Zone of Muwaqqar Chalk Marl Formation and from the overburden of Um Rijam Chalk and Wadi Shallala Chalk aquifers. The evaluations of the main hydrochemical processes affecting the groundwater quality were carried out by interpreting the ionic relationships and the water quality types using Piper and Durov diagrams. Comprehensive statistical analyses (Factor and Cluster Analyses) were conducted on the water quality parameters. The factor analyses can extract four factors from the water quality parameters of the Harrana wells Area-1 and for Azraq wells in Area-2. These factors are used to interpret the different geochemical processes affecting the groundwater quality parameters. Cluster analyses divided the Harrana wells into three groups. Cluster I included 26 wells with minimum mean concentrations of cations and anions, while cluster III included the wells with the highest concentrations in the water quality parameters. Cluster II included eight wells with intermediate concentrations. Azraq Area-2 wells are clustered into three groups. Cluster I includes seven wells with lowest water quality (highest concentrations); cluster II includes 12 wells and exhibits the lowest concentrations of ions and cluster III includes five wells that show intermediate ions concentrations. The interpretation indicated that the primary factors controlling the groundwater chemistry of Azraq and Harrana appeared to be dissolution processes of the carbonate rocks containing traces of evaporitic minerals, ion exchange and reversal ion exchange processes. Moreover, the water quality in the study areas is not suitable for drinking purposes.

Sequence stratigraphic context and organic geochemistry of Palaeogene oil shales, Jordan

The potential oil shales of the Palaeogene Muwaqqar Chalk Marl and Umm Rijam Chert Limestone formations are investigated from a subsurface location in the west of Jordan. Detailed organic geochemistry data is placed in the context of a sequence stratigraphic framework derived from vertical foraminiferal biofacies and lithological changes and biostratigraphically calibrated using planktonic foraminiferal biozonation. This shows that the transgressive systems tract of a Selandian (P4, probably P4a) sequence has the best potential in the studied section to generate oil if subjected to induced pyrolysis. A Ypresian (no older than E2) transgressive sequence has some potential, whilst highstand systems tracts offer the least potential. Both the sequence model and oil shale potential compares well with equivalent age sediments in Egypt and highlights that whilst the Maastrichtian portion of the Muwaqqar Chalk Marl Formation is often regarded as the key interval for oil shale prospectivity, parts of the Paleocene succession also have some potential.

Intermediate members of the lime-monteponite solid solutions (Ca1−xCdxO, x = 0.36–0.55): Discovery in natural occurrence

Lime-monteponite solid solutions [(Ca,Cd)O ss] with 58.5–73.3 wt% CdO were discovered as an accessory phase in medium-temperature combustion metamorphic (CM) spurrite-fluorellestadite/fluorapatite marbles from central Jordan. The type locality is situated in the northern part of the Siwaqa complex (Tulul Al Hammam area), the largest area of the “Mottled Zone” Formation in the Dead Sea region. The marbles were derived from bitumen-rich calcareous marine sediments of the Muwaqqar Chalk Marl Formation, which have high Cd, Zn, U, and Ni enrichments and contain Cd-rich wurtzite and sphalerite. Oxidative sintering of these sediments at 800–850 °C gave rise to unusual oxide accessories: lime-monteponite solid solutions, Cd-bearing Ca and Zn aluminate—tululite, zincite, and Zn-, Ni-, and Cu-rich periclase. Cadmium incorporation into different oxides was controlled by steric factors, while Cd [6] → Ca [6] was the principal isomorphic substitution. The intermediate members (Ca 0.645 Cd 0.355 )O–(Ca 0.453 Cd 0.547 )O with a halite-type structure have a cadmium incorporation ratio (K Cd = Cd mineral /Cd rock ) of about 843 and are the main sites for cadmium in CM marbles. In supergene environments, at low water/rock ratios, (Ca 1−x Cd x )(OH) 2 ss ( x ≤ 0.5) constitute the main secondary phase after (Ca,Cd)O ss. At higher water/rock ratios and in the presence of Cl − and F − in the solutions, calcium, and cadmium precipitated as separate phases {fluorite (CaF 2 ) and basic cadmium chloride [Cd(OH) 2−x Cl x )]}. A part of cadmium becomes retained in calcium silicate hydrates. The common occurrence of anhydrous (Ca,Cd)O grains in natural rocks, only partly altered to (Ca,Cd)-hydroxide after at least 100 ka exposure to weather and climate, proves that both phases are effective long-term Cd immobilizers.

CHEMICAL COMPOSITION OF THE MINERAL MATTER OF THE ATTARAT UM GHUDRAN OIL SHALE, CENTRAL JORDAN

The concession area of the Jordan Oil Shale Energy Co (JOSE) is located in the southern border zone of the Attarat Um Ghudran deposit, next to the Wadi Maghara deposit, both consisting of marinite type oil shale (OS). These deposits of the Upper Cretaceous to Lower Paleogene Muwaqqar Chalk-Marl Formation form a huge north-southward elongated oil shale basin in Central Jordan, with resources over 55 billion tons. JOSE has drilled a regular grid of boreholes with a full coring of the up to 90 m thick OS seam and its lower and upper contact layers. Visually, the OS unit is a rather homogenous dark-colored (grey, black, brownish grey) succession of finely bedded (laminated) kerogen-bearing carbonate rocks that has been in earlier papers described as a uniform lithological unit. The aim of the geological and lithological studies of the JOSE exploration area was (i) to investigate the vertical variation of OS composition and, if present, to define layers within the OS unit, and (ii) to identify lithological varieties and chemical composition of OS present in different layers. On the basis of field evidence, downhole gamma-logging, chemical analyses and other criteria, an original detailed scheme of the layered structure of oil shale and barren rocks was introduced. A total of eight OS layers (indexed as A, B1, B2, C, D, E1, E2, E3) and at least four barren dolomitic limestone interlayers were distinguished. The present publication is dedicated to the chemical study of the layers and the total OS seam. A representative gapless collection of 632 conventional core samples from 12 cores serves as the base for the comparative study of the layers. Two main (SiO2, CaO) and two subordinate chemical (Al2O3 and P2O5) components of the mineral matter (MM), and loss on ignition (LOI 500 °C) approximately reflecting the content of organic matter (OM), are the basic variables dis- cussed. Contents of SiO2 and CaO always show negative correlation,

Tululite, Ca14(Fe3+,Al)(Al,Zn,Fe3+,Si,P,Mn,Mg)15O36: a new Ca zincate-aluminate from combustion metamorphic marbles, central Jordan

Tululite (Ca14(Fe3+,Al)(Al,Zn,Fe3+,Si,P,Mn,Mg)15O36 (the hypothetical end-member formula Ca14{Fe3+O6}[SiO4][Zn5Al9]O26) (IMA2014-065) is a new natural Ca zincate-aluminate, identified in medium-temperature (800–850 °C) combustion metamorphic (CM) spurrite-fluorellestadite marbles from central Jordan. The type locality (Tulul Al Hammam area) is situated in the northern part of the Siwaqa complex, the largest area of the “Mottled Zone” Formation in the Dead Sea region. The marbles originated from bitumen-rich chalky marine sediments of the Maastrichtian-Paleogene Muwaqqar Chalk Marl Formation, which have low clay content (and, consequently, low Al) and high Zn, Cd, and U enrichments. The bulk CM rocks derived from the low-Al protolith have unusually high (Zn + Cd)/Al ratios (~0.2) and, as a result, a mineralogy with negligibly small percentages of Ca aluminates having low Ca:Al molar ratios (minerals of mayenite supergroup, Ca:Al = 6:7) common to most of calcareous CM rocks in the Mottled Zone. Instead, the mineral assemblage of the Zn-rich marbles contains tululite, with high Ca:Al = 2.55 molar ratios and Zn substituting for a large portion of Al (Zn:Al = 1.1). Tululite occurs in thin clusters as irregular grains with indented outlines (20–100 μm in size), having typical open-work textures associated with rock-forming calcite, fluorellestadite, spurrite, and accessory Zn-rich periclase, lime-monteponite solid solutions, calcium uranates, and zincite. Marbles also bear brownmillerite, dorrite, fluormayenite, high-fluorine Ca aluminate, and lakargiite. Secondary phases are brucite, gel-like calcium silicate hydrates and calcium silicate aluminate hydrates, including Zn- and U-bearing and Cd-rich compounds, Si-bearing hydrated compounds after calcium uranates, and basic Cd chlorides. The empirical formula of the holotype tululite (a mean of 32 analyses) is (Ca13.29Cd0.75)Σ14.04(Al5.46Zn5.20Fe3+ 2.23Si0.95Mn3+ 1.01Mg0.78P0.41)Σ16.04O36. Tululite is cubic, space group F23; a = 14.9346(4) A; V = 3331.07(15) A3, Z = 4. The strongest lines of the X-ray powder-diffraction pattern [d, A – (I obs )] are: 2.874(57), 2.640 (100), 2.524(42), 2.278(41), 1.760(54), 1.725(25), 1.524(33), 1.500(33). The crystal structure was solved from single-crystal X-ray diffraction data and refined to wR2 = 0.0672 on the basis of 913 unique reflections with I 0 > 2σ(I). Tululite belongs to a group of compounds with the general formula Ca14 MT 15O35+x (0 ≤ x ≤ 1), and is a new structure type. The tetrahedral framework of tululite structure is formed by T7O13 secondary building units (SBU), which consist of four corner-linked tetrahedra sharing a common oxygen atom and three tetrahedra sharing two O atoms with the neighbor SBU. Ca2+ cations occupy three positions; two of them also contain a minor amount of Cd2+. The Ca sites surround an island (Fe3+,Al)O6 octahedron and a (Si,P)O4 tetrahedron in the centers of framework cages at the junction of eight SBUs. The (Fe3+,Al)O6 octahedron is coordinated by fourteen Ca positions into a 6-capped cube, whereas the (Si,P)O4 tetrahedron is coordinated by six Ca positions into a regular octahedron. The structural formula of tululite is Ca14{Fe3+O6}M1[(Si,P)O4]T1[(Al,Zn)7O13]2 T2-T4. The mineral is yellow with greenish tint, transparent with vitreous luster, non-fluorescent under ultraviolet light, and showing neither parting nor cleavage; Mohs hardness is 6.5. The density calculated on the basis of the empirical formula is 3.826 g/cm3. Its Raman spectrum shows strong bands at 522, 550 and 636 cm−1 and weak bands at 199, 260, 295, 456, and 754 cm−1.

Geology and metallogeny of Jordanian uranium deposits

Uranium mineralisation has been known within the Hashemite Kingdom of Jordan for a long time and in 2014 maiden mineral resources were estimated for the Central Jordan Uranium Project (CJUP) following the reporting principles of the JORC Code (). Based on this estimate the CJUP contains 269 mt of mineralisation at an average grade of 135 ppm U3O8 (36·4 kt of contains U3O8) within an Inferred Resource. The objective of this paper is to describe the geology and the metallogeny of uranium mineralisation in Jordan, providing new insights into this mineralisation that remains largely unknown outside of the country. Most of Jordan's territory is covered by platform sedimentary rocks that generally formed during the Cretaceous and Paleogene. The majority of uranium mineralisation is confined to Upper Cretaceous sediments, in particular the Al Hisa Phosphorite (AHP) and the Muwaqqar Chalk Marl (MCM) formations. The MCM formation hosts surficial type-mineralisation that is mainly concentrated in a narrow, approximately 4·5 m thick layer that is distributed close to the topographic surface and is independent of phosphorite beds. This mineralisation, termed ‘surficial’, is the economically most important type of uranium in Jordan and currently represents the main exploration target in this area. The main uranium minerals within the surficial layer are uranium vanadates, colloquially referred as carnotite group minerals. The average uranium grade rapidly decreases below a depth of 4–5 m, although mineralisation continues to depths of 30–40 m. Beneath the surficial layer, uranium mineralisation is distributed as lenses that are generally small and discontinuous. This mineralisation, termed ‘Deep’, has many common features with the surficial mineralisation, including similar mineralogy and chemical composition and may represent a transition between surficial and phosphorite-hosted types. The metallogeny of surficial uranium mineralisation is well studied, although several important questions remains unanswered. In particular, close spatial relationships between pyrometamorphic marbles and the uranium mineralisation can be observed on regional geological maps and in the field. Two different models have been proposed to explain the formation of the pyrometamorphic marbles in central Jordan, namely the burning of bituminous marls and an alternative model involving the combustion of deep reservoirs of hydrocarbon gases relating to mud volcanoes. Tectonic faults have also possibly played a role in the distribution of uranium mineralisation in central Jordan. This is in particular relevant for the Khan Azabib area where higher grade mineralisation and their associated gamma anomalies are broadly coincident with regional faults. These faults may have acted as permeable zones, facilitating migration of the hyperalkaline solutions that leached uranium from the host rocks. Eventually, the liberated uranium was redistributed by supergene processes towards the surface, where uranium minerals precipitated along the contact between saprolite and fresh to weakly weathered rocks. In summary, the uranium deposits of Central Jordan resulted from the interplay of sedimentary, tectonic, and metamorphic events, with the final impact made by climatic factors and chemical weathering processes. The AHP formation hosts phosphorite-hosted type mineralisation that formed as a result of the synsedimentary concentration of uranium in apatite and is abundant in the Hasa–Qatrana area of central Jordan. The surficial parts of the phosphorite-hosted uranium mineralisation have also been partially modified by weathering, which has released uranium from apatite and redistributed and precipitated it as ‘carnotite’. This type of mineralisation is present at the Sahb El Abyad prospect located in the south-eastern part of Jordan. Uranium mineralisation also occurs in hydrothermal veins that cross-cut Cambrian rocks exposed along the plate margin in the Dead Sea rift valley. This mineralisation type is different to the mineralisation within the central Jordanian deposits and it is rare in Jordan, so far being found only in the Dana area.

CALCIUM URANIUM OXIDE MINERALS FROM CENTRAL JORDAN: ASSEMBLAGES, CHEMISTRY, AND ALTERATION PRODUCTS

Unusual combustion-metamorphic phosphorus-rich varicolored marbles of the Tulul Al Hammam area in central Jordan, 60 km east of the Dead-Sea – Jordanian Transform, bear abundant accessory grains and crystals of primary double Ca-U(VI) oxide minerals (calcium uranates). The Ca-U(VI) oxides are associated with typical pyrometamorphic minerals, such as sulfate-bearing fluorapatite, fluorellestadite, spurrite, fluormayenite, dorrite, brownmillerite, srebrodolskite, periclase (Zn-, Ni-, Co-, and Cu-rich), lime, and U-rich lakargiite. The primary Ca-U(VI) oxide minerals have large compositional ranges, with 45.07 to 82.54 wt.% UO3 and 16.66 to 56.05 wt.% CaO corresponding to CaO-to-UO3 molar ratios from 1 to 6. The marble-hosted calcium uranate minerals are most often Ca3UO6 or Ca2UO5 existing as individual crystals (5 to 25 µm), while CaUO4 is a rarer phase found as small inclusions in fluorapatite/fluorellestadite. These compounds were identified by SEM microscopy, electron microprobe analyses, and Raman spectroscopy. The existence of other calcium uranate minerals (Ca4UO7, Ca5UO8, Ca3U2O9, and Ca6UO9) has been inferred from SEM and electron microprobe analyses of single grains (<10 µm). The mineral assemblages correspond to high-temperature ( ca . 800–850 °C) and ambient pressure conditions of spurrite-merwinite metamorphic subfacies. The Ca-U(VI) oxide minerals formed during Quaternary combustion metamorphism of U-rich bituminous calcareous sediments (oil shales of the Maastrichtian-Paleocene Muwaqqar Chalk Marl Formation, Belqa Group). Numerous pseudomorphs after cracked and hydrated calcium uranate grains with a wide range of impurities (Si, Fe, Al, and F) may be due to chemical weathering and hydration of the primary calcium uranate minerals. A more hydrous analogue of the so-called x-phase (Ca2UO5•1.5–3H2O) was found as a main secondary phase after the primary Ca-U(VI) oxide minerals. The unusual mineralogy and chemistry of the varicolored marbles can provide clues to the behavior of trace elements in concrete, their stability in radioactive waste repositories, and to purification of metals under dry annealing conditions.

Sequence stratigraphy and evolution of Eshidiyya phosphorite platform, southern Jordan

Eshidiyya platform, southern Jordan, is the site for huge Upper Cretaceous phosphorite deposits in excess of 1000 million tons. The sections studied consist of two 3rd order sequences. The phosphorites in both sequences were deposited during the transgressive systems tracts (TST). Phosphogenesis had paused or became minor during the HST when the oyster buildups and the shed coquinoidal limestone dominated the sequence. By the end of the HST, topmost coquinoidal limestone was karstified and red-stained with soil-like material, thus indicating an erosional unconformity or a type 1 sequence boundary (SB1). Very thin, red, pure micrite, devoid of fossil, reworked and/or eroded represents the LST of the 2nd sequence. The TST of the 2nd sequence started with the upper phosphorite horizon and continued throughout the Muwaqqar Chalk Marl Formation (MCM). However, the MCM started with a fall in relative sea level possibly due to restriction by the oyster buildups in the north, then open marine circulation resumed.

Sedimentology of the Late Quaternary Wadi Hasa Marl Formation of Central Jordan: a record of climate variability

The sedimentary features and fossils within the Wadi Hasa Marl Formation coupled with optical luminescence chronology indicate alternating wet and dry periods have occurred on the Jordanian plateau since the last interglacial. The Jurf Ed Darawish Member rests unconformably on the Maastrichtian Muwaqqar Chalk Marl Formation and is composed predominantly of poorly sorted, clast-supported conglomerate. Palaeocurrents and clast composition indicate provenance from Cretaceous sedimentary rocks and Tertiary basalts to the west and southwest of the study site and the facies suggest a flashy alluvial depositional environment probably similar to the modern wadis. The overlying Burma Member consists of bedded grey-green clayey silts and marls with calcrete profiles, up to 1.2 m thick, and isolated gravel lenses. The fine-grained sediments contain charophytes, ostracods, bivalves and various species of gastropod indicating normal freshwater lacustrine conditions. The calcretes contain a poorly preserved fauna suggesting lacustrine deposition followed by subaerial exposure and pedogenesis. Three optical luminescence ages have been obtained from the Burma Member which suggest that the member ranges in age from >111 ka through to <40 ka. The facies variations are indicative of climatic fluctuations in Jordan during this period and human artefacts are found embedded in the sediments. This preliminary study suggests that the Late Quaternary central Jordan sedimentary record may preserve valuable evidence of complex climatic variation which will supplement the data from the Jordan Valley where tectonic activity complicates the sedimentary record.