Phosphorites

The importance of Rare Earth Elements (REE) in phosphorites had attracted attention in the last few years, since these enriched elements could be subtracted as by product in the fertilizer industry. In addition, their role in depositional environment is well established. Therefore, thirty seven phosphorite samples from all over Jordan; twelve from SE, fourteen from central and eleven from NW were analyzed for REE and other elements. The results show that REE are depleted relative to worldwide phosphorites (35.64- 85.23ppm) and have seawater pattern indicating the incorporation from seawater. The depletion increases southwards due to (i) less time for incorporation of the REE at the sea floor, (ii) source rock of REE which is sandstone, (iii) very shallow burial, (iv) slight weathering of phosphorites. Ce shows a negative anomaly increasing northwards indicating more oxic environment. Y and Sc also are analyzed and treated in this manuscript since Y has similar behavior to REE and Sc...

Food is essential for human survival. Phosphate rock, a critical mineral for the production of fertilisers, is key to achieving food security globally. This article reviews the mineralogy, geological nature, processing and economics of this important resource. Apatite is the primary mineral of phosphate rock. Phosphate rock occurs geologically as sedimentary phosphorites, guano, and igneous deposits. Phosphate rocks are beneficiated by flotation. Morocco (Western Sahara, inclusive) and China rank amongst the highest producers of phosphate rock. Africa holds over 80 percent of world's phosphate rock reserves. As at the year 2016, the price of marketable phosphate rock was USD 72 per metric tonne.

Sixty three samples representing the phosphorite deposits of the Al-Kora province in northwest Jordan are analyzed for their major and certain trace elements including the rare earths and uranium. They are collected from four sections: Tubna, Dair Abu Sa'id, Wadi Al-Arab and Wadi Ziglab.
The samples studied are mainly phosphorite packstone/grainstone consisting of phosphate intraclasts and vertebrate skeletal fragments (bone and teeth) of varying sizes, associated with minor carbonate wackestones. Laminated, in situ phosphorites, sometimes called pristine phosphorites, are also present. The Al-Kora phosphorites are authigenic; i.e. precipitated from the interstitial solutions enriched with the phosphate ion. Carbonate fluorapatite (CFA) or francolite is the dominant mineral. Geochemical data suggest that the analyzed elements can be grouped into: a) land-derived detrital clay group (Al2O3, Fe2O3, TiO2, K2O, Cr, Ga, Hf, Nb, Rb, Th, and Zr). This group constitutes less than 5% of the total elemental concentrations in the analyzed samples, b) marine or seawater-derived phosphate-carbonate group (P2O5, CaO, MgO, Na2O, Ba, Sr, U, Y, and the 14 REE), making the bulk of the samples studied, c) organic matter/detrital clay group (Cr, Ni, Mo, Cu, Pb, As,  Zn, and Sb). Uranium substitutes for Ca in the CFA structure with a range from 1 to 186 ppm for all samples including carbonates, with an average of 58.4 ppm. Average for the phosphate-only samples is 101 ppm.
The shale normalized REE patterns exhibit a distinct seawater-derived mineral patterns. The patterns are characterized by an enhanced negative Ce anomaly and an enriched heavy REE. This signal (pattern) seems to have survived the phosphogenesis processes.  Average Ce anomaly is – 0.76, including the carbonate samples. It indicates the fractionation of Ce3+ into Ce4+ and the deposition of the latter in oxic, or possibly oxygen minimum, seawater.  It, thus, confirms the oxic water conditions of the Neo-Tethys Ocean at the time of deposition

Abstract: We provide a compilation of geology of uranium and thorium potential resources in the Ordovician black shale (graptolite argillite), Cambrian–Ordovician shelly phosphorite and in the secondary resources (tailings) of Estonia. Historical and new geological, XRF and ICP-MS geochemical data and ArcGIS modeling results of elemental distribution and tonnages are presented. The Estonian black shale contains 5.666 million tons of U, 16.533 Mt Zn, 12.762 Mt Mo, 47.754 Mt V and 0.213–0.254 Mt of Th. The Estonian phosphate resources, altogether about 3 billion metric tons of phosphate ore, contain about 147,000 to 175,000 tons of U. Rare earth element concentrations in the phosphorite ore average at 1200–1500 ppm of ΣREE. Thorium can also be a possible co-product. The mining waste dump at the Maardu contains at least 3650 tons of U and 730 tons of Th. The Sillamäe radioactive waste depository contains about 1200 tons of U and 800 tons of Th. Due to the neighboring geological positions, as well as environmental constraints and mining technologies, the black shale and phosphorite can be treated as a complex multi-resource, possibly at the continental scale, which needs to be extracted together.

Pakistan is an agricultural economy country that relies on fertilizers. Among these fertilizers, phosphatic fertilizers play a vital role in plant growth and soil fertility. The nutrition efficiency of fertilizers depends on the quality of rock used as feedstock. In this, the quality of rock phosphate has been assessed from different areas of the Hazara division of Pakistan. Results elucidated that the Hazara basin contains phosphorite from 19% to 30% P 2 O 5 and Fe 2 O 3 from 0.80% to 2.51%. Deposits of Qalandar Abad contains the highest Fe 2 O 3 i.e. 2.36%. Whereas, deposits of Lagar Ban contains only 0.9% Fe 2 O 3. Deposits of Tornai-Mangal contains 30% and 1.25% of P 2 O 5 and Fe 2 O 3 , respectively. Therefore, these deposits are the best feedstock for the production of phosphate fertilizers.

The deposition of major Precambrian phosphorites was restricted to times of global change and atmospheric oxygenation at both ends of the Proterozoic. Phosphorites formed after highly positive carbon isotope excursions in carbonates deposited during the Paleoproterozoic Lomagundi-Jatuli event and the Neoproterozoic Cryogenian and Ediacaran periods. The correlative step-wise rise in atmospheric oxygen over the Proterozoic has been linked to changes in the carbon cycle. However, the postulated ...

During the Mid-Cretaceous thin siliciclastic and carbonate sediments rich in glauconite and phosphorites were deposited on the Southern part ot the Helvetic Shelf. These deposits overlie the shallow-water Urgonian Limestones, and they are covered by pelagic biomicrites of the Seewen Limestones.
New stratigraphic units are proposed for these Mid-Cretaceous deposits:
- the Aravis Formation composed of two members, the Bossetan Member (0-40 m, Upper Aptian) and the Platé Member (0,1-20 m, Late Aptian to Mid-Upper Cenomanian). These are separated by the important late-Aptian unconformity,
- the Freu Beds (0-6 m, late Albian to early Coniacian), with facies of the Aravis Fm reworked in an Albian to early Coniacian micritic matrice.
The palaeontology of the ichnofauna and the microbial encrustations are given close attention. The vertical sequence of taphocenoses indicates a deepening trend from Aptian to Turonian.
The study of the Albian-Cenomanian deposits gives evidence of sedimentary areas partially characterized by erosionat unconformities. As the fauna indicates a marine environment and no signs of emersion were detected, the erosional surfaces are probably a consequence of a submarine erosion. These discontinuities lie closer when going from N-E to S-W, i.e. from distal to proximal part of the shelf. This shinkage is strongest in the Eastern part of the Bauges massif where the top of the Urgonian limestones contains solution cavities measuring several meters.
A synthesis of the data provides an account of the sedimentary evolution of the Southern Helvetic shelf. This evolution began in the early Upper Aptian by the drowning of the Urgonian platform. A mineralised hard-ground bearing phosphatized lag-deposits and ammonites veneers the rudistid-miliolid limestones.
During the Upper Aptian, sandy biocalcarenites containing small phosphoclasts (Aujon beds) were deposited in the restricted area of the "Platé-Dents du Midi". Then, after a period of fine-grained siliciclastic deposition (Borderan Beds), mixed-sedimentation with bio- and siliciclastic components took place (Colombière Beds). Fauna composition and depositional features indicate a storm-influenced environment below faire-weather wave base. This sedimentation was interrupted by the late-Aptian unconformity (L.A. unconformity), an irregular surface showing plurikilometer scours cut into the Upper Aptian deposits.
From late Upper Aptian to late Upper Albian, phosphate-rich greensands, containing fossiliferous condensed horizons (Lindars Sandstones) were deposited. The main internal unconformities identify two depositional units within the Lindars Sandstones. In the first, late Aptian to Middle Albian, the sediments show numerous lateral facies and thickness changes. Some of these changes are partly controlled by the irregular shape of the L.A. unconformity: phosphate-rich condensed deposits with microbial encrustations were deposited on the high parts, while siliciclastic-rich deposits, five to ten times thicker than the phosphate-rich deposits, were accumulated within the erosional scours.
The second unit of the Lindars Sandstones is separated from the first one by the Upper Albian unconformity which is commonly cut into by the deep Late Upper Albian unconformity. So the Upper Albian deposits are generally very condensed and represented only by polyzonal phosphatic conglomerates in which Lower and Middle Albian faunas may be reworked.
During the Lower to Mid-Cenomanian, an hemipelagic carbonate sedimentation with low sedimentation rate (i.e. < 20 cm/year) was established. The deposits are represented by thin glauconitic biomicrites containing phosphatic nodules and mini-stromatolites. These deposits cover or rework the Albian phosphatic conglomerates. Despite the disappearance of the glauconite and the phosphorites during the Mid-Cenomanian, the very low sedimentation rates persisted until the Turonian whereas pelagic biomicrites were deposited.
Confrontation of the sedimentary data with the structural data provides a palaeogeographical framework for the Southern Helvetic Shelf. Two kinds of shelf edge are suggested: the first is represented by a sedimentary prism prograding to the Ultrahelvetic Basin, the second by a structural shoal probably inherited from the Jurassic period of rifting.
The genesis of the condensed deposits is approached in the conclusion. The good correlation existing between the main unconformities detected in this work and the main sea-level falls of HAQ et al. (1987) suggests an eustatic control of the sedimentary sequences. But this control is not by itself sufficient and it cannot explain the low sedimentation rates during Albian and Cenomanian as well as the juxtaposition of contemporaneous accumulation areas and strong condensation areas.
Taking account of the oceanic circulation in the western Tethys, a complementary sedimentary control with subsurface currents is proposed. These currents could also explain the large erosional scours associated to the main unconformities. Therefore the long axis of these erosional figures more or less parallel to the shelf edge could indicate the direction of current flow which appears locally influenced by the structural shoals.
Finally, during the Mid Cretaceous, the important distribution of condensed deposits on the European and Apulian Margins gives a reconstruction of the oceanic subsurface circulation in the Western Tethys flowing from the Western Carpathian domain to the Betic Cordillera.

Key-words: Stratigraphy, Alps, Helvetic domain, Aptian, Albian, Cenomanian, Shelf, Unconformities, phosphorites, stromatolites, submarine erosion, oceanic circulation, Western Tethys.

The end-Triassic mass extinction (ETE) is associated with a rise in CO2 due to eruptions of the Central Atlantic Magmatic Province (CAMP), and had a particularly dramatic effect on the Modern Fauna, so an understanding of the conditions that led to the ETE has relevance to current rising CO2 levels. Here, we report multiple phosphorite deposits in strata that immediately precede the ETE at Williston Lake, Canada, which allow the paleoenvironmental conditions leading up to the mass extinction to be investigated. The predominance of phosphatic coated grains within phoshorites indicates reworking in shallow water environments. Raman spectroscopy reveals that the phosphorites contain organic carbon, and petrographic and scanning electron microscopic analyses reveal that the phosphorites contain putative microfossils, potentially suggesting microbial involvement in a direct or indirect way. Thus, we favor a mechanism of phosphogenesis that involves microbial polyphosphate metabolism in w...

The end-Triassic mass extinction (ETE) is associated with a rise in CO 2 due to eruptions of the Central Atlantic Magmatic Province (CAMP), and had a particularly dramatic effect on the Modern Fauna, so an understanding of the conditions that led to the ETE has relevance to current rising CO 2 levels. Here, we report multiple phosphorite deposits in strata that immediately precede the ETE at Williston Lake, Canada, which allow the paleoenvironmental conditions leading up to the mass extinction to be investigated. The predominance of phosphatic coated grains within phoshorites indicates reworking in shallow water environments. Raman spectroscopy reveals that the phosphorites contain organic carbon, and petrographic and scanning electron microscopic analyses reveal that the phosphorites contain putative microfossils, potentially suggesting microbial involvement in a direct or indirect way. Thus, we favor a mechanism of phosphogenesis that involves microbial polyphosphate metabolism in which phosphatic deposits typically form at the interface of euxinic/anoxic and oxic conditions. When combined with data from deeper water deposits (Kennecott Point) far to the southwest, it would appear a very broad area of northeastern Panthalassa experienced anoxic to euxinic bottom water conditions in the direct lead up to the end-Triassic mass extinction. Such a scenario implies expansion and shallowing of the oxygen minimum zone across a very broad area of northeastern Panthalassa, which potentially created a stressful environment for benthic metazoan communities. Studies of the pre-extinction interval from different sites across the globe are required to resolve the chronology and spatial distribution of processes that governed before the major environmental collapse that caused the ETE. Results from this study demonstrate that fluctuating anoxic and euxinic conditions could have been potentially responsible for reduced ecosystem stability before the onset of CAMP volcanism, at least at the regional scale. The end-Triassic mass extinction (ETE) appears nearly coincident with the emplacement of the Central Atlantic Magmatic Province (CAMP) ~201.51 million years ago 1-5. Approximately 80% of all marine and terrestrial species became extinct during the ETE making it the second biggest biodiversity 6,7 and the third biggest ecological crisis 8 during the Phanerozoic. Proposed causes of the mass extinction include CAMP-related global warming 4,9,10 , global cooling 11 , ocean acidification 12-15 , sea-level changes 16 , and ocean anoxia 3,16-18. The knowledge base of the conditions leading up to the ETE is poorly resolved, as the main focus has remained on the timing associated with an initial emplacement of CAMP. Yet, recent studies of the pre-extinction interval reveal biotic, climatic

This  paper presents new stratigraphic and palaeontological dat about Aptian to Turonian deposits from the southern part of the Helvetic zone. It is based on detailed analysis of over 120 stratigraphic sections for which the following information is provided: location, geographic co-ordinates, accessibility, detailed lithologic log, list of collected fossils which are housed in the Museum of Natural History of Geneva. Precise dating of deposits of middle Aptian to middle Cenomanian age is based on the discovery of numerous ammonites ( over 3300 specimens) within eight disctinctive phosphate-rich levels. The dating of rocks formed during time interval late-Albian-Turonian is further refined by the study of planktonic foraminifers in thin-sections. The paper is illustrated by 40 plates, 26 of which are devoted to the ammonites only (see vol. planches). Among those, over 20 type-specimens from the famous Pictet Collection are illustrated photographically for the first time.

Swab phosphorite deposit was discovered in 1986 in the Western Desert of Iraq. It is of Paleocene age and belongs to the Akashat Formation. The industrial ph os orite consists of (9 − 16) m thick bed of fine sand size well sorted phosphate peloids and coated grains wit h calcite cement , occasionally rich in organic mat ter . The average P2O5 grade is about 22% and the average stripping ratio is about 3. The overburden consists of Paleocene and Eocene carbonate rocks. The strata are gently d ipping towards north with little structural deforma tion. The new deposit, with its 3.5 billion tons of reserves, puts Iraq among the leading countries in proved phosphorite

We provide a compilation of geology of uranium and thorium potential resources in the Ordovician black shale (graptolite argillite), Cambrian–Ordovician shelly phosphorite and in the secondary resources (tailings) of Estonia. Historical and new geological, XRF and ICP-MS geochemical data and ArcGIS modeling results of elemental distribution and tonnages are presented. The Estonian black shale contains 5.666 million tons of U, 16.533 Mt Zn, 12.762 Mt Mo, 47.754 Mt V and 0.213–0.254 Mt of Th. The Estonian phosphate resources, altogether about 3 billion metric tons of phosphate ore, contain about 147,000 to 175,000 tons of U. Rare earth element concentrations in the phosphorite ore average at 1200–1500 ppm of ΣREE. Thorium can also be a possible co-product. The mining waste dump at the Maardu contains at least 3650 tons of U and 730 tons of Th. The Sillamäe radioactive waste depository contains about 1200 tons of U and 800 tons of Th. Due to the neighboring geological positions, as wel...

In this study we investigate the radiological hazard of naturally occurring radioactive material in Tunisian and Algerian phosphorite deposits. Eight samples of phosphorite were collected from the phosphorite mines. The Tunisian and Algerian phosphorites occur in the Late Paleocene and Lower Eocene (Ypresian-Lutetian) in age (Béji Sassi 1984 and Zaïer 1999). Activity concentrations in all the samples were measured by alpha spectrometry and gamma spectrometry. Alpha spectrometry analyses show that the specific activity values of 238U, 234U and 235U in the samples of Tunisian phosphorite were 327±7 (321–327), 326±6 (325–331) and 14.50±0.72 (13.90–15.57) Bq kg−1, respectively. Specific activity measured by gamma spectrometry in the samples of the Tunisian and Algerian phosphorite shows a small difference. Specific activity levels of 40K, 226Ra, 232Th, 235U and 238U in the phosphorite samples from Tunisia were, respectively, 71.10± 3.80, 391.54±9.39, 60.38±3.74, 12.72±0.54 and 527.42± 49.57 Bq kg−1 and Algeria were 15.72±1.73, 989.65±12.52, 12.08±1.20, 47.50±1.52 and 1,148.78±7.30 Bq kg−1, respectively. The measured value of specific activity of 232Th and 40K in the Tunisian phosphorite samples is relatively higher than  that found in the samples of Algerian phosphorite. The measured  activity of uranium (238U) in the Tunisian phosphorite (527±49) Bq kg−1 is lower than in Algerian phosphorite. The measured activity of 238U in the Tunisian phosphorite samples was (527–1,315±65) 238U Bq kg−1 which is higher than its maximum background value of 110 Bq kg−1 in soils of the various countries of the world (Tufail et al. Radiat Meas 41:443–451, 2006). Different geological origins of phosphorites deposits are the main reason for the large spread in worldwide specific activities. The obtained results of uranium concentrations in phosphorites of different types (Algerian and Tunisian) demonstrate that the uranium concentrations are mainly governed by the phosphatic material. The present study reveals that phosphorite deposits contain natural radioactivity higher than background level