Glauconitic Deposits Research Articles

Glauconite Deposits in Russia: Geological Position, Formation Conditions, and Development Perspectives

Glauconite Deposits in Russia: Geological Position, Formation Conditions, and Development Perspectives

An Assessment of Alternate Fertilizer Potential of Glauconite Deposits in India using Simple Beneficiation Methods

Abstract This study presents an assessment of alternate fertilizer potential of glauconite deposits in India with precise stratigraphy, dimension of the deposit, and its K2O contents for understanding their alternate potash fertilizer potential. Further, it provides simple beneficiation methods to separate glauconite from the rest of the sediments. Many of the glauconite deposits, particularly those of Precambrian age, are considerably thick and are laterally extensive. Although the content of K2O is low in the bulk rock, it is moderate to high in the glauconites. The glauconite content of the original deposits is low, mostly in the range of 10 to 20 wt%. Inexpensive and simple methods such as sieving and electromagnetic separation enhance the glauconite content up to 57 wt% in selected samples. This study is crucial for planning alternatives of conventional potash fertilizer, which are expected to be exhausted in the near future.

Paleogeographic, paleoclimatic and sea-level implications of glauconite deposits in Egypt: A review

Glauconite deposits are confined to the Western Desert in Egypt of four different sequences and ages from older to younger include, 1) Lower Cenomanian Bahariya Formation, 2) Lower-Middle Campanian Qusseir Formation, 3) Upper Campanian Duwi Formation, and 4) Lutetian-Bartonian Hamra Formation.Lower Cenomanian, Upper Campanian and Lutetian-Bartonian glauconites occur as pellets, while the Lower-Middle Campanian glauconite occurs as fine-grained particles of non-pelletal texture. Based on K2O contents, the Lower Cenomanian and Upper Campanian glauconites are classified as slightly evolved, while the Lower-Middle Campanian and Lutetian-Bartonian glauconite are categorized as evolved. Positive correlations between K2O and Fe2O3 in the Bahariya Formation, Qusseir Formation and Hamra Formation deposits suggest a layer lattice glauconitization mechanism for these deposits. On the other hand, the lack of correlation between Fe2O3 and K2O declines the layer lattice formational mechanism for the Duwi Formation glauconite. A neo-formation mechanism was suggested for this glauconite. Rare earth elements patterns are the same in the four deposits and resemble the shallow sweater pattern.The four glauconite deposits formed in shallow marine environments and might correspond to major eustatic transgressive and global warming events. Glauconite of the Bahariya Formation corresponds to the Early Cenomanian Tethys major transgression in Egypt and can be correlated to the Albian/Cenomanian global cycle boundary as well as the early Cenomanian “hot greenhouse”. The sequence boundary near the topmost part of the Qusseir Formation matches the global warming of the Middle Campanian Event (MCE). The upper Campanian glauconite of the Duwi Formation occurs as lowstand wedge and may correlate to the late Campanian climatic warm optimum. The stratigraphic position of the Hamra glauconite above the unconformity surface refers to transgressive phase that may match with latest Lutetian major sequence boundary (Lu4) and global warming event of the Middle Eocene Climatic Optimum (MECO).Paleogeographic maps show that the Western Desert of Egypt during Cenomanian and Lower Campanian covered by shallow marine setting, which match with the proposed setting for the glauconites in these ages. However, paleogeographic maps for the Upper Campanian and Middle Eocene were modified to fit with the suggested setting of glauconites of these epochs. The prevalence of shallow marine setting during these four ages interprets the restricted occurrences of glauconites at the Western Desert of Egypt during these epochs.

Перспективы комплексного освоения Бакчарского железорудного месторождения (Западная Сибирь, Россия)

Актуальность исследования. Приводится анализ и оценка комплексных ресурсов Бакчарского месторождения, которое до настоящего времени считалось исключительно железорудным месторождением морских оолитовых железняков. Изученные второстепенные минеральные продукты могут быть предметом добычи для первоочередной окупаемости объекта. Основная цель работы заключалась в качественной и количественной оценке потенциальных попутных минеральных компонентов Бакчарского месторождения. Использовались следующие аналитические методы: оптическая микроскопия и петрографический анализ, сканирующая электронная микроскопия, рентгенодифракционный анализ, рентгенофлуоресцентный анализ. В результате проведенных исследований получены следующие основные выводы. Ресурсы глауконита на месторождении составляют около 800 млн т. В пределах западного детально разведанного участка площадью 5 км2 ресурсы глауконита оцениваются в 34 млн т при среднем содержании 27,8 %, из которых 4,6 млн т составляют глауконитолиты, 18,1 млн т - глауконитовые песчаники и 11,3 млн т - глауконит-шамозит-гетитовые ооидовые железняки. Туронские песчанистые алевролиты ипатовской свиты обогащены магнетитом и ильменитом при их суммарном среднем содержании в породе 15,2 %. Наличие этих минералов обеспечивает высокий магнитный сигнал (магнитная восприимчивость) отложений: 113,4…295,7·10-5 ед. Си. (первый и второй квартиль, соответственно). Ресурсы магнетита и ильменита по 13 пересечениям в пределах западного участка месторождения составляют около 2,75 млн т. Из этих ресурсов на долю TiO 2 приходится около 815 тыс. т (при среднем содержании TiO 2 29,6 %), а на долю Fe 2 O 3 - 934,9 тыс. т (при среднем содержании Fe 2 O 3 34 %). Текстурные особенности описанных пород (слабая цементация) позволяют рекомендовать скважинную гидродобычу как метод первоочередной разработки как глауконитовых залежей, так и магнетит-ильменитового пласта.

The timing of oceanic anoxic events in the Cretaceous succession of Cauvery Basin: Constraints from 40Ar/39Ar ages of glauconite in the Karai Shale Formation

This study presents 40Ar/39Ar ages of autochthonous glauconites from the lower segment of the onshore Karai Shale Formation of the Cauvery Basin that constrain its age from 100.3 ± 0.7 to 92.6 ± 0.6 Ma. The 40Ar/39Ar plateau ages of the 3 glauconite samples are consistent with the existing biostratigraphic age of Late Albian to Middle Turonian of the Karai Shale Formation. These ages are significant because of the occurrences of oceanic anoxic event (OAE)1d and oceanic anoxic event (OAE)2 in contemporaneous offshore deposits, the Sattapadi Shale and Bhuvanagiri Formation, respectively. Although in the onshore deposits, the glauconite ages mark condensed deposits of the transgressive Karai Shale. As onshore glauconitic deposits may be transitional to organic‐rich black shale deposits offshore in modern and ancient sedimentary settings, the 40Ar/39Ar ages precisely constrains the timing of Cretaceous oceanic anoxic events reported in the Cauvery Basin.

ДИНАМИКА АДАПТАЦИОННО-ПРИСПОСОБИТЕЛЬНЫХ ПРОЦЕССОВ ВЫСОКОПРОДУКТИВНОГО ЗАВОЗНОГО СКОТА МЯСНОГО НАПРАВЛЕНИЯ В УСЛОВИЯХ ЯКУТИИ

ДИНАМИКА АДАПТАЦИОННО-ПРИСПОСОБИТЕЛЬНЫХ ПРОЦЕССОВ ВЫСОКОПРОДУКТИВНОГО ЗАВОЗНОГО СКОТА МЯСНОГО НАПРАВЛЕНИЯ В УСЛОВИЯХ ЯКУТИИ

The economic potential of El-Gedida glauconite deposits, El-Bahariya Oasis, Western Desert, Egypt

The mining work at El-Gedida iron mine, El-Bahariya Oasis, in the Western Desert of Egypt extracts commercial iron ore deposits without attention paid to the large glauconite deposits overlying these iron ore deposits. For this reason, the present paper aims at evaluating and attracting the attention to these glauconite deposits as alternative potassium fertilizers. The study was achieved by investigating mineralogical, physical and chemical properties of the green deposits. Mineralogical and physical properties involved the determination of glauconite pellets content in different grain size fractions relative to impurities and the analysis of the percentage of clay matrix and grain size distribution. Different pre-treatment strategies and methods including comminution, sieving, magnetic separation, and X-ray diffraction were used for investigating those mineralogical and physical properties. On the other hand, chemical analyses included potassium content, heavy metal concentrations, and pH and salinity measurements. The major elements and trace elements were measured using ICP-OES and the pH was measured using a pH conductometer. Moreover, this study investigated the nature of grain boundaries and the effect of sieving on glauconite beneficiation. Results of this study suggest that El-Gedida glauconite deposits are mineralogically, physically and chemically suitable for exploitation and can be beneficiated for use as an alternative potassium fertilizer.

Upper Eocene glauconites from the Bahariya depression: An evidence for the marine regression in Egypt

Glauconite deposits at the Bahariya Oasis are reported as Cenomanian and Upper Eocene deposits. The Upper Eocene glauconite deposits have received little attention in comparison with the Cenomanian counterpart. In the present study, glauconite deposits belonging to the Hamra Formation were investigated in terms of petrography, mineralogy and geochemistry to determine their origin and demonstrate their significance as proxies for the paleoenvironmental conditions.Petrographically, glauconite occurs as green to yellowish green, oval, sub-oval, rounded, fine to medium-grained (150–400 μm), moderately sorted pellets set in clayey matrix. Mineralogically, the studied deposit consists mainly of glauconite in association with quartz, feldspar, hematite, alunite, halloysite and calcite, whereas clay fractions (<2 μm) are composed essentially of glauconite with small amounts of illite-smectite mixed layer and kaolinite. Chemically, the studied glauconite contains K2O at average of 7.47%. Thus, it can be classified as evolved glauconite. The morphology of glauconite as oval, sub-oval, rounded pellets with deeply penetrating fractures on some grain surfaces, the moderate sort of these pellets and the occurrence of argillaceous matrix consisting of glauconitic plasma, illite-smectite mixed layer and kaolinite are considered criteria for the parautochthonous origin of the Upper Eocene glauconite. Moreover, the geochemistry of rare earth elements along with stratigraphy and the occurrences of many glauconitic ironstone horizons within the studied section proposed that the deposition of the studied glauconite, at depth of 100 m, started with marine transgression and terminated by marine regression during the Upper Eocene.

Glauconitic deposits at Julegård on the south coast of Bornholm, Denmark dated to the Cambrian

Bioturbated, glauconitic siltstones and sandstones are overlain by presumed Upper Triassic deposits at coastal exposures at Julegård on the south coast of Bornholm. These glauconitic deposits have not previously been dated. A 40Ar-39Ar dating of the glaucony gives an age of 493 ± 2 Ma suggesting the deposits belong to the Lower Cambrian Norretorp Member of the Læså Formation. The shallow marine deposits are strongly bioturbated, but only a single ichnoassociation is represented. The ichnogenus is referable to either Trichophycus Miller and Dyer, 1878 or Teichichnus Seilacher, 1955. Rare examples of Rusophycus Hall, 1852, probably trilobite trace fossils, are also represented.

Pathways for arsenic from sediments to groundwater to streams: Biogeochemical processes in the Inner Coastal Plain, New Jersey, USA

The Cretaceous and Tertiary sediments that underlie the Inner Coastal Plain of New Jersey contain the arsenic-rich mineral glauconite. Streambed sediments in two Inner Coastal Plain streams (Crosswicks and Raccoon Creeks) that traverse these glauconitic deposits are enriched in arsenic (15–25 mg/kg), and groundwater discharging to the streams contains elevated levels of arsenic (>80 μg/L at a site on Crosswicks Creek) with arsenite generally the dominant species. Low dissolved oxygen, low or undetectable levels of nitrate and sulfate, detectable sulfide concentrations, and high concentrations of iron and dissolved organic carbon (DOC) in the groundwater indicate that reducing environments are present beneath the streambeds and that microbial activity, fueled by the DOC, is involved in releasing arsenic and iron from the geologic materials. In groundwater with the highest arsenic concentrations at Crosswicks Creek, arsenic respiratory reductase gene ( arrA) indicated the presence of arsenic-reducing microbes. From extracted DNA, 16s rRNA gene sequences indicate the microbial community may include arsenic-reducing bacteria that have not yet been described. Once in the stream, iron is oxidized and precipitates as hydroxide coatings on the sediments. Arsenite also is oxidized and co-precipitates with or is sorbed to the iron hydroxides. Consequently, dissolved arsenic concentrations are lower in streamwater than in the groundwater, but the arsenic contributed by groundwater becomes part of the arsenic load in the stream when sediments are suspended during high flow. A strong positive relation between concentrations of arsenic and DOC in the groundwater samples indicates that any process—natural or anthropogenic—that increases the organic carbon concentration in the groundwater could stimulate microbial activity and thus increase the amount of arsenic that is released from the geologic materials.

Mediterranean Neocomian belemnites, part 3: Valanginian-Hauterivian belemnites

The classical papers of Raspail (1829, 1830) and Duval-Jouve (1841) described a wide range of belemnite species, mainly from the Lower Cretaceous of the Castellane-Peyroules area (Alpes de Haute-Provence, France). The present work focuses mainly on the biostratigraphy of these previously described belemnite taxa for their stratigraphic relationships had not been determined precisely. Here, biostratigraphy is related to the lithologic successions and faunal associations (ammonites) of various outcrops in the area studied. Complementary data were obtained from the La Lagne, Les Allaves and Pas d'Escale sections (Alpes de Haute-Provence, France). And, in order to attain a better understanding of the stratigraphic distribution of Late Valanginian belemnites in condensed glauconitic deposits, these assemblages are compared with belemnites from deeper water successions in the Angles, Source de l'Asse de Moriez, Cheiron areas and those in the vicinity of La Charce and Vergol that are even deeper.

The Potential for Environmentally Sound Development of Marine Deposits of Potassic and Phosphatic Minerals Offshore, Southern Africa

Extensive potassium and phosphorous-rich mineralization occurs on the outer continental shelf of the southern and west coasts of South Africa and Nambia. This article reviews the potential of exploiting these deposits in an environmentally sound manner for the manufacture of fertilizer. At present, reserves of potash and phosphate fertilizer are exploited from terresterial deposits, the majority being surface mined. The use of fertilizer in South Africa has shown no growth in the past 13 years, and, in some years, usage has even declined. On average, over the last decade, South Africa has consumed 2 million Mt of fertilizer (including nitrogen) per annum, the vast majority of phosphate fertilizer being produced by FOSKOR from the Phalaborwa Igneous Complex. Potash fertilizer is imported into South Africa. Although fertilizer consumption is expected to decrease in the short-term, there are good future prospects for the domestic and international fertilizer market. Considerable research into both glauconitic (containing K 2 O) and phosphatic deposits along the southern African continental shelf indicate that these sedimentary deposits have a complex genesis and mineralization. Of the total K 2 O reserves of 1300 million Mt on the southern African margin, 1000 million Mt is located off the southern African west coast, and the remainder situated on the Agulhas Bank. The largest glauconite concentration ( - 300 million Mt K 2 O) off southern Africa lies west of Saldanha Bay, South Africa. The distribution of P 2 O 5 off southern Africa is dominated by the vast deposit between Walvis Bay and Luderitz, Nambia. This reserve is estimated to contain 1000 million Mt of greater than 5% P 2 O 5 in a relatively small area of about 10000 km2. The phosphorite deposit south of Saldanha Bay constitutes a reserve of - 3500 million Mt of apatite and the deposit on the Agulhas Bank comprises 5500 million Mt. The phosphate deposit off Saldanha Bay occurs as an extensive, low to medium grade deposit. Although vast resources of potash and phosphatic minerals occur along the southern African outer continental shelf the expensive nature of marine exploitation may render most of these deposits, especially the phosphates, subeconomic. The low price of fertilizer andextensive natureontheonland deposits, although confined to asmallnumber of countries, mean that it will not be financially viable to extract these deposits. Assuming high grade glauconitic sand with the right composition can be located, the high market price indicates good future prospects for these potash deposits.

Lower Ordovician conodonts, reworking, and biostratigraphy of the Orreholmen quarry, Västergötland, south‐central Sweden

Abstract The quarry at Orreholmen, Billingen‐Falbygden District, Province of Västergötland, in south‐central Sweden was sampled for conodonts. The local stratigraphy, which is complicated, has previously been determined on the basis of macrofossils. Upper Cambrian and lower Tremadocian bituminuous shales with stinkstone lenses are overlain by glauconitic deposits grading into “orthoceratite limestone” of Arenigian age. The results reported here of conodont investigations from various levels throughout the sequence demonstrate the absence of certain levels in the Lower Tremadoc and the lower Upper Tremadoc, possibly of a part of the basal Arenig and of a level at the Latorp‐Lanna Stage boundary (lower middle Arenig). Comparison of data from Orreholmen with observations from sections in other parts of Baltoscandia, information on evolutionary lineages of conodonts and evidence from redeposited conodont elements were combined to produce reconstructed stratigraphie sequences. Particularly important for these results was the analysis of the reworked faunal components, which are unusually common at this locality. For the first time the presence of conodonts from basal Tremadoc beds has been proved in Sweden. The Ordovician part of the sections includes (in terms of conodont biostratigraphy) strata from the Cordylodus lindstromi Zone to near the top of the Paroistodus originales Zone. Löfgren, A., 1996: Lower Ordovician conodonts, reworking and biostratigraphy of the Orreholmen quarry, Västergötland, south‐central Sweden. GFF, Vol. 118 (Pt. 3, September), pp. 169–183. Stockholm. ISSN 1103–5897.

Traps Associated with Paleovalleys and Interfluves in an Unconformity Bounded Sequence: Lower Cretaceous Glauconitic Member, Southern Alberta, Canada (1)

The Glauconitic member in Badger, Little Bow, Retlaw, and Turin fields is an unconformity bounded sequence that formed on an ancient coastal plain in response to relative sea level fluctuations. The member consists of valley-fill and inter-valley strata. Valley-fill sandstone bodies are thick elongate pods that formed from inner estuarine bars when sedimentation was laterally confined between valley margins. Inter-valley sandstone bodies are thin discontinuous sheets that accumulated during highstands when outer estuarine embayments covered interfluvial areas adjacent to associated valleys. Numerous oil pools are stratigraphically trapped within quartzose sandstones in valley-fill and inter-valley strata of the Glauconitic member in the study area. Common updip seals for these reservoirs are (1) intra-sequence facies changes from sandstone to shale, and (2) low-permeability lithic sandstones that fill the cross-cutting paleovalleys of a younger sequence. Traps associated with many valley-fill pools are enhanced by differential-compaction anticlines. Several oil pools in the study area are hosted by discrete quartzose sandstone bodies that lie beneath a valley filled with low-permeability lithic sandstone. These quartzose sandstone bodies are interpreted to be remnants of older Glauconitic deposits that escaped erosion when a younger valley incised into, and followed the trend of, one or more older Glauconitic valleys.

Palaeozoic oolitic ironstones on the North American Craton

More than 40 mostly minor Palaeozoic oolitic ironstones (OI) accumulated on low-latitude cratonic North America, almost entirely in USA. A few Middle Cambrian OI, among the oldest anywhere, were deposited on the western cratonic shelf of USA. Widely scattered Late Cambrian ones developed on the southwestern, southeastern and northeastern flanks of the Transcontinental Arch. Middle Ordovician OI were deposited on the cratonic interior and on the southern and southeastern cratonic margins. In latest Ordovician time Neda OI spread across north-central USA east of the Arch and south of the Laurentian upland. Minor ones developed in the southern part of the Taconian foreland basin after major orogeny. Early and Middle Silurian Clinton OI flourished throughout the foreland basin in eastern USA, producing the largest OI deposit on the North American craton. Minor early Late Silurian OI accumulated in the central part of the basin. Middle and Late Devonian OI in the Acadian foreland basin in northeastern cratonic USA developed progressively westward of the encroaching Catskill delta. An isolated Middle Devonian one accumulated in southwestern cratonic USA, and latest Devonian ones in north-central USA east of the Arch. During this Palaeozoic episode sites of OI deposition shifted eastward across the craton. Most of the OI were deposited during a hiatus in normal sedimentation, accumulating in the upper part of shoaling-upward sequences. Some early Palaeozoic ones occur in glauconitic siliciclastic-carbonate facies and contain mostly spherical hematitic ooids. These suggest derivation from iron-rich soils developed on glauconitic deposits. OI in wholly siliciclastic facies, containing distorted chamositic ooids with cores of mud peloids, were common in later Palaeozoic time. These OI, like many other Phanerozoic ones, suggest a synsedimentary to early diagenetic origin.

The removal of metals and ammonium by natural glauconite

Glauconite deposits, naturally occurring aluminosilicates rich in iron and potassium, are abundant in New Jersey, Delaware, and Maryland. The presence of these deposits has been shown to be responsible for a high content of sodium in ground water for certain region of Maryland. The ammonium and metal (Pb, Zn, and Cd) removal capability was investigated in both batch and column reactors using natural, NaCl- and NaOH-treated glauconite-bearing sand. Ammonium removal by glauconite is a typical ion exchange process. Both ion exchange and adsorption are responsible for matal removal. Important factors such as pH, sample source, and method of pretreatment were studied. The metal removal follows the order of Pb(II) > Zn(II) > Cd(II). The surface acidity of the glauconite is characterized by an acidmetric-alkalimetric titration. The acidity constants, pK 1 i, and pK 2 i, and 3.6 and 6.0, respectively.

The uranium content of submarine phosphorite and glauconite deposits on Chatham Rise, east of New Zealand

The distribution of uranium in a number of submarine phosphorite and glauconite samples from Chatham Rise, and in associated phosphatic limestones and cetacean bones, has been determined by neutron activation analysis. Uranium values in the phosphatised deposits were found to be variable, with most containing between 150 and 250 ppm U 3O 8 but values up to 435 ppm U 3O 8 being not uncommon. The glauconite samples had low uranium contents in the range 6–17 ppm U 3O 8, except for two samples that yielded 99 and 132 ppm U 3O 8.

An electron microprobe study of glauconites from the continental margin off the west coast of South Africa

The rich glauconite deposits off the south and west coasts of southern Africa originated by erosion of Cretaceous and Tertiary bedrock during mainly Tertiary transgressive/regressive cycles. This work, the first major electron microprobe investigation of glauconite, was undertaken to provide reliable chemical data of uncontaminated, unaltered glauconite pellets and to trace the chemistry of the glauconitization process. The data suggest that Fe is emplaced into the clay structure very early in the glauconitization process, possibly by a mechanism which is independent of and prior to the fixation of K. The sympathetic relationship between K 2O and MgO indicates that some Mg is located in the interlayer position.

Glauconite

The term glauconite has been employed in two senses. It has been used most commonly as a morphological term for sand-sized greenish grains found in sedimentary rocks, but also as a name for a specific mineral species, a hydrated iron-rich micaceous clay mineral. The two uses are not synonymous, since not all morphological glauconite consists exclusively of mineral glauconite, nor is the latter restricted in its occurrence to such pellets. Mineral glauconite in sensu lato is a random interstratification of nonexpanding 10A˚layers and expanding montmorillonitic layers. The amount of expandable layers may be over 50 % but it is customary to restrict the name mineral glauconite in sensu stricto to varieties with less than 10 % expandable layers. The variation in amount of expandable layers explains many of the observed variations in the properties of glauconite including chemical composition (especially potassium content), thermal characteristics, cation exchange capacity, colour, refractive index and specific gravity. Mineral glauconite is believed to form by the progressive absorption of potassium and iron by a degraded layer silicate lattice of low lattice charge and elimination of other silicate-lattice types under suitable environmental conditions, of which the most critical seems to be the redox potential. The catalytic activity of marine organisms is no longer thought to be essential, although decaying organic matter and empty foraminiferal tests supply the ideal environment for glauconite genesis. The process of glauconitization is arrested by rapid sedimentation, so that there is a relationship between the variety of mineral glauconite formed and the nature of the host rock. Glauconite is found associated particularly with marine transgressions. Morphological glauconite grains are believed to form as casts, faecal pellets or by accretionary growth, but may have their morphology modified by subsequent re-working. A number of characteristic internal and external morphologies have been recognised. The wide range of environmental conditions suitable for its formation and its common detrital occurrence debars the use of glauconite in palaeo-environmental studies. Its major use in geology is for the absolute age dating of sedimentary rocks by the K-Ar method. Glauconitic deposits have no present day commercial value, but soils formed on glauconitic parent materials are notable for their fertility. Glauconite weathers by loss of potassium to produce a montmorillonitic or vermiculitic product with the release of, or oxidation of, structural iron, so that the grain has the appearance of having weathered to limonite.

Stratigraphie et paleogeographie du Cretace inferieur de l'anticlinal de Gourdan et du bassin du Var moyen de Daluis a la Mescla

Abstract The Var basin (Provence Alps, southeastern France) is separated from the Esteron basin to the south by the Gourdan anticline. During much of early Cretaceous time the geography of this area closely resembled the present, with two basins separated by a fault scarp at the position of the present Gourdan anticline. In the Var basin a thick Vocontian-type section of dark pelagic marls to the west graded into a neritic section of thicker Berriasian sediments, very calcareous Valanginian sediments, and glauconitic Hauterivian deposits to the east. In the Esteron basin to the south, sediments were subneritic, with numerous interruptions of sedimentation and abundant glauconite. After Bedoulian (early Aptian) time the scarp disappeared so that the basins coalesced and sedimentation became uniform.