The Numidian sand event in the Burdigalian foreland basin system of the Rif, Morocco, in a source-to-sink perspective

During the Tertiary evolution of the Western Mediterranean subduction system, a migrating foreland basin system developed between the Maghrebian orogenic belt and the adjacent African Craton. However, a comprehensive reconstruction of the foreland basin systems of the Rif Chain is still missing. By integrating field observations with quantitative biostratigraphic data from calcareous nannofossil assemblages, sandstone composition, and detrital zircon U-Pb geochronology from selected stratigraphic successions, we reconstruct the foreland basin system that developed in the early Miocene in front of the growing Rif orogen. The successions analyzed are representative of (1) the classical “Numidian Facies” from the Intrarifian Tanger Unit and (2) the Numidian-like deposits (mixed successions) of the “Mérinides Facies” from the “Maghrebian Flysch Basin” and the “Beliounis Facies” from the Predorsalian Unit. Our petrographic analyses and detrital zircon U-Pb ages show that the quartzarenites of the “Numidian Facies” originated from the African Craton, whereas the sublitharenites and feldspathic litharenites from the Mérinides and Beliounis Facies originated from a cratonic area and the exhuming Rif Chain. Our biostratigraphic analyses suggest a simultaneous arrival of the quartz grains in the Numidian, Mérinides, and Beliounis deposits, which indicates that their deposition occurred at ∼1 m.y. (ca. 20−19 Ma, early Burdigalian) and allows us to delineate the early Burdigalian foreland basin system of the Rif Chain. The foreland depozone received the “Numidian Facies,” the foredeep-hosted ∼2000 m of the “Mérinides Facies” and the Beni Ider Flysch, whereas the wedge-top depozone was characterized by deposition of the “Beliounis Facies.” The Numidian Sandstones and the Numidian-like deposits analyzed in Morocco show the same age as similar deposits from Algeria, Tunisia, and Sicily, which suggests a comparable early Burdigalian tectono-sedimentary evolution along the southern branch of the Western Mediterranean subduction-related orogen.

Provenance controls on volcaniclastic beach sand: example from the Aeolian Archipelago, Mediterranean Sea

Sand and sandstone composition of volcanic origin may be clues to the provenance of the sediments and sedimentary rocks. Volcaniclastic provenance studies contribute significantly to unravel the sediment generation and provenance under investigation that in the Aeolian archipelago comprise preserved units of outcrops dominated by lava flows intercalated with air fall tephras as source rocks. The aim of this paper is the study of the petrographic composition and the textures of beach sands that may be used as a guide for the interpretation of provenance and origin of beach sand(stone)s rich in volcanic debris transported into deeper water. The composition of Aeolian beach deposits defines a single immature petrofacies with a high amount of unweathered glass and mafic minerals. Panarea island is dominated by dacites and new grain categories have been proposed to discriminate this provenance. Surface processes such as mechanical erosion (mass wasting and surface runoff) produce an overestimation of mafic components, with respect to the felsic ones in the beach sand fraction.Supplementary material at https://doi.org/10.6084/m9.figshare.c.5608950

Sandstone Petrology and Provenance in Fold Thrust Belt and Foreland Basin System

The sandstone composition of foreland basin has a wide range of provenance signatures, reflecting the interplay between flexed underplate region and abrupt growth of the accreted upper plate region. The combination of contrasting detrital signatures reflects these dual plate interactions; indeed, several cases figure out that the earliest history of older foreland basin infilling is marked by quartz-rich sandstones, with cratonal or continental-block provenance of the flexed underplate flanks. As upper plate margin grows over the underplate, the nascent fold-and-thrust belt starts to be the main producer of grain particles, reflecting the space/time dependent progressive unroofing of the subjacent orogenic source terranes. The latter geodynamic processes are mainly reflected in the nature of sandstone compositions that become more lithic fragment-rich and feldspar-rich as the fold-thrust belt involves the progressive deepest portions of upper plate crustal terranes. In this context sandstone signatures reflect quartzolithic to quartzofeldspathic compositions.

Sandstone Composition and Provenance of the Nari Formation, Central Kirthar Fold belt, Pakistan

The Oligocene-Early Miocene Nari Formation is widely distributed in the Kirthar thrust-fold belt. The formation in the study area is mainly consist of sandstone and shale. Field observations and detailed petrographic study reveal that these sandstones are mostly fine to medium grained, subangular to subrounded and poorly to moderately sorted. Detrital grains are dominantly quartz ranging in proportion 36-76%, feldspar 7-17% and lithic grains 1-13%, reflecting that these sandstones are compositionally submature. Quartz is mostly monocrystalline with some polycrystalline grains. Feldspar is dominantly plagioclase (albite) with some alkali feldspar (orthoclase and microcline). Lithic fragments are siltstone, mudstone and chert. Biotite and muscovite are present as accessory minerals. Heavy minerals such as apatite, tourmaline, and zircon are present in trace amount. The QFL diagrams show that the sandstones of the Nari formation are subarkose and lithic subarkose. The QtFL, QmFLt ternary diagrams and paleocurrent direction suggest that the sediments were transported from the Indian shield exposed to the northeast of the Nari Basin.

A geochemical and biostratigraphic approach to investigating regional changes in sandstone composition through time; an example from Paleocene–Eocene strata, Taranaki Basin, New Zealand

A geochemical and biostratigraphic approach has been applied to investigate the spatial and stratigraphic variability of Palaeogene sandstones from key wells in Taranaki Basin, New Zealand. Chronostratigraphic control is predominantly based on miospore zonation, while differences in the composition of Paleocene and Eocene sandstones are supported by geochemical evidence. Stratigraphic changes are manifested by a significant decrease in Na2O across the New Zealand miospore PM3b/MH1 early Eocene zonal boundary, at approximately 53.5 Ma. The change in Na2O is associated with a decrease in baseline concentrations of many other major (MnO, CaO, TiO2) and trace elements, and is interpreted to reflect a significant change in sandstone maturity. Paleocene sandstones are characterized by abundant plagioclase (albite and locally Na–Ca plagioclase), significant biotite and a range of heavy minerals, while Eocene sandstones are typically quartzose, with K-feldspar dominant over plagioclase, low mica contents and rare heavy minerals comprising a resistant suite. This change could reflect a change in provenance from local plutonic basement during the Paleocene Epoch to relatively quartz- and K-feldspar-rich granitic sources during Eocene time. However, significant quartz enrichment of Eocene sediment was also likely due to transportation reworking/winnowing along the palaeoshoreface and enhanced chemical weathering, driven in part by long-term global warming associated with the Early Eocene Climatic Optimum. The broad-ranging changes in major-element composition overprint local variations in sediment provenance, which are only detectable from the immobile trace-element geochemistry.

Provenance reconstructions. Article 1. Mineralogical and petrographic approaches and methods

Research subject. This is the first in the series of four articles, which aims to review existing provenance reconstruction tools.Methods and materials. The data obtained during evaluation of different sandstone allothigenous components was used as a basis for analysis. The data was collected from the Upper Riphean Zilmerdak Formation Bir’yan Member and the Upper Vendian Bassa Formation (Southern Urals); the Upper Devonian Kodinka and Ust’kodinka formations (Middle Urals); the Lower Cretaceous Sortym Formation (Western Siberian sedimentary megabasin, Bolshekhetskaya depression).Results. The sandstone composition patterns of the lithostratigraphic units under study allowed the most common provenance features to be established by means of comparing data obtained by various diagrams.Conclusions. It is established that only the Kodinka, Ust’kodinka and Sortym sandstone compositions can be used as a source for rock reconstruction analysis, while the Bir’yan and Basa sandstone compositions have undergone massive transformations.

Petrophysical Signatures and Water-Reservoir Potential of Southern Apennines Turbiditic Sandstones Suites

After the seismic event of Irpinia (Southern Apennines), occurred on November 23rd 1980, the Pavoncelli tunnel, that used to supply with water the Puglia Region, was seriously damaged. Because of the strategic importance of this civil engineering work, a new water tunnel named Pavoncelli-bis that should substitute the previous one, was built and finally tested during the end of the 2019. The geological features of the area, highlighted the presence of three main siliciclastic formations (Corleto, pre-Numidian/Numidian and Castelvetere formations), crossed by the tunnel trace, that were petrophysically analyzed through the mercury injection porosimetry for a better definition of their petrophysical signatures and related water-reservoir potential at regional scale as hydrocarbon-reservoir potential. Data highlighted the presence of two clusters: one represented by the Corleto and Pre-Numidian Fms. showing good permeability (respectively 181.70 mD and 122.25 mD in median) and low porosity (respectively 4.56 % and 3.94 % in median); the other, represented by the Castelvetere Fm. highlighting good porosity (9.58 % in median) and a very low permeability (4.84 mD in median). Permeability, more than porosity, affects the cluster differentiation, whereas the other variables (average pore diameter and nanopores volume) do not show any particular trend. All these petrophysical parameters were compared with the sandstone composition (Qm, F, Lt), highlighting that porosity results negatively correlated to monocrystalline quartz (Qm) and positively correlated with feldspars (F). The lithic fragments values (Lt) are sparse and do not show any specific trend. The variability of porosity is directly linked with the diagenetic processes that interested the clusters of the Corleto and pre-Numidian Fms. (rich of Qm) and the Castelvetere Fm. (rich of F). Particularly, where quartz is more abundant, quartz cementation and overgrowth are more efficient and widespread, resulting in a reduction of the porosity. On the contrary, where feldspars are abundant, during diagenesis their dissolution can create new pore spaces and also clay-minerals with a better porosity than the previous feldspars. Moreover, clay-minerals can coat the quartz grains present in the sandstones inhibit the porosity loss of the quartz cementation and overgrowth. However, despite an increase in porosity, permeability decreases because the authigenic clays is mainly formed by isolated and blind pores.

Sedimentology and fossil vertebrates of the Santa Cruz Formation (early Miocene) in Lago Posadas, southwestern Patagonia, Argentina

Lago Posadas is located at the foot of the Southern Patagonian Andes, in southwestern Argentina, where the early Miocene Santa Cruz Formation (SCF) shows thick and laterally continuous exposures. This region has been scarcely explored for fossil vertebrates since the first efforts by J.B. Hatcher in 1898-99. In this contribution, we performed sedimentologic and paleontological studies in order to reconstruct depositional environments and the associated fossil vertebrate fauna. Sedimentologic data suggest that the sedimentary record begins with restricted marine-estuarine deposits grading upward to fluvial floodplains and fluvial channels. Extensive floodplains, occasionally interrupted by low-sinuosity, sand-dominated channels, show dominant reddish coloration, moderate to low paleosol development, abundant crevasse splay sandstones and lack of vegetal remains, suggesting deposition in a low gradient, oxygenated setting under elevated sedimentation rates. Vertical stratigraphic trends are subtle, suggesting little paleoenvironmental changes during deposition of the whole SCF in this region. Paleocurrent directions, sandstone composition and paleogeographic reconstructions all indicate that deposition of the SCF was strongly associated to the contemporaneous uplift of the Andes. Fossil vertebrates analyzed are the result of our collecting effort and revision of museum collections. The faunal assemblage includes 31 taxa: 28 mammals and three birds. Mammals belong to the main groups recorded in other areas of the SCF (metatherians, xenarthrans, notoungulates, litopterns, astrapotheres and rodents). The assemblage allows a Santacrucian Age sensu lato assignment for the fauna at Lago Posadas. Taxonomic revisions of several taxa are necessary to further adjust the biostratigraphic significance of this association. The combined record of arboreal, browser and frugivores, on one side, and grazer mammals and rheas, on the other, suggest the presence of both trees and open environments. Frugivores, among primary consumers, and the secondary consumers guild are under-represented due to sample and fossil remain size biases. The sedimentologic and paleontological record of the SCF in Lago Posadas suggests that the uplift of the Southern Patagonian Andes acted as a primary control on basin subsidence and sediment supply, providing a special signature for sub-andean localities. However, previously registered climatic changes are poorly recorded in this study.

The Effect of Sandstone Composition on Distribution of Tafoni Landforms in the Aghajari Sandstone, Northwest of Masjed Soleyman, Iran

The Aghajari sandstone layers are located in the west of Zagros Mountains from several centimeters thicknesses to maximum 6 meters with carbonating content. Laboratory and fieldwork show high amount of carbonate content through sandstone layers and tafoni and honeycombs (THs) in early layers. In the study area three parameters have the most effective impactful factors in tafoni and honeycombs (THs) including matrix, carbonate content, and porosity. In this study result shows overlays of high ranges of CaCO3, porosity, and low matrix in the early layers (especially in A, B, C, D, and H layers) with tafoni and honeycombs (THs). Overall, we conclude that matrix and CaCO3 (carbonate clast including carbonate lithics, fragment fossils, and Pellet) and porosity have direct relationships and matrix reverse relationships with tafoni and honeycombs (THs) in the Aghajari sandstones layers.