Beachrock Formation Research Articles

Beachrock: A chronological benchmark for Late Holocene build-up on the coast of Israel

Beachrock formations are proxies of coastal morphodynamics, and are thus commonly utilized for paleoenvironment interpretations. Linear beachrock outcrops parallel to the shoreline are typical of the Mediterranean coastline of Israel. A new geomorphic and sedimentological analysis of beachrock, integrated with relative and absolute geochronology, characterizes their clastic composition and determines their ages. In-situ beachrock outcrops in the sandy beaches of the Sharon coast of central Israel are composed of quartz sand, shells and shell fragments, and show a significant contribution of fragmented rocks from the coastal cliff. Sections of beachrocks analyzed using portable Optically Stimulated Luminescence (pOSL) provided a relative chronological framework within and between the sections. The results show a moderate optic signal accumulation, indicating a gradual beach build-up during initial beachrock formation stages. Optically Stimulated Luminescence (OSL) ages indicate deposition of unconsolidated beach sediments dated to about 1600–800 years before present (BP). The sediment burial at the former foreshore enabled rapid consolidation in the intertidal zone.

Mid-latitude microbial-mediated modern beachrock formation (Santa Maria di Ricadi - Southern Italy)

Mid-latitude microbial-mediated modern beachrock formation (Santa Maria di Ricadi - Southern Italy)

Contemporary beachrock formation at Arrigunaga beach (Bizkaia, Spain) on anthropogenic slag

The large, thick beachrock of Arrigunaga beach (Bizkaia, Spain) is unusual among beachrocks because of (a) Its location, at 43ºN latitude; (b) The substrate that was cemented, largely consisting on smelter slag mixed with natural beach sediment; (c) The timing and amount of slag dumping at sea, with millions of tons of waste dumped in the short interval AD 1902–1966; (d) The sudden cessation of dumping (AD 1966), followed by immediate beachrock exhumation and retrogradation and (e) An aggressive engineering intervention (AD 1999), supposedly aimed at beach regeneration, with imported bioclastic sands, resulting in additional weak cementation of the residual blocks. Thickness of the beachrock and the identification of internal clasts attest for a multiepisodic process with at least three main cementation steps and several CaCO3 polymorphs precipitated from mixed marine and freshwaters. Evidence of bacterial remains suggests that biological activity helped to trigger cementation. C and O isotopic values obtained in the cements confirm the dominance of mixed marine and freshwaters composition. Exact knowledge of the start and finishing dates of slag dumping permits to tightly constrain the rapid cementation, which was already evident at least since AD 1924, that produced the beachrock, as well as its evolution towards its current fast and complete disappearance.

UAV, GIS, and Petrographic Analysis for Beachrock Mapping and Preliminary Analysis in the Compressional Geotectonic Setting of Epirus, Western Greece

Beachrocks are generally mapped on the coastline surface and/or in a low depth in the subtidal zone in coastlines and are cemented chiefly by carbonate material. Their outcrops may vary from a tenth of meters to a tenth of kilometers in length. Along the Epirus coast, in Greece, beachrocks outcrops are laying on the coastline for more than ten kilometers. In the present work, we used Unmanned Aerial Vehicles (UAVs), in situ sampling, and the Geographical Information System (GIS) to map three beachrock areas with a length of 500 m to 600 m each. In synergy with extended mineralogical and petrographic analyses, we provide preliminary data about the geographical distribution and the mineralogical differences of these beachrocks. Furthermore, for the first time, we tried to investigate the correlation between the geotectonic setting of the broader area and the beachrock extent, shape, and petrographic parameters. The laboratory analyses proved that the beachrocks belong to a similar depositional zone of a marine–vadose environment. Despite variations in the textural petrographic, features among the specimen’s analyses permit us to consider these sedimentary rocks as not a uniform outcrop. It is indicated that the beachrock formation and the cementation progress in the study area are both controlled by active reverse faults and diapiric or tectonic anticlines.

Beachrock Formation Mechanism Using Multiproxy Experimental Data from Natural and Artificial Beachrocks: Insights for a Potential Soft Engineering Method

Beachrocks are a window to the past environmental, geological, sedimentological and morphological conditions that were dominant in the coastal zone during their formation. Furthermore, beachrocks have the ability to reduce coastal erosion impact on sandy beaches. This study focuses on the beachrock formation mechanism through the comparison of cement characteristics, mineral chemistry and sedimentology of beachrock occurrences from two different geological and geographical localities: Diolkos, Corinth, Greece and Sumuide, Okinawa, Japan. In addition, in order to investigate a potential soft engineering method to protect coasts from erosion, artificial beachrock samples were created in vitro using sand samples and ureolytic bacteria from both areas under accelerating conditions. For Okinawa artificial beachrock experiments, the bacteria Pararhodobacter sp. was used, and for Diolkos, it was the bacteria Micrococcus yunnainensis sp. For the natural beachrocks, a multi-analytical approach was accomplished with the use of microscopic investigation, a scanning electron microscope, energy-dispersive X-ray spectroscopy, X-ray diffraction and X-ray fluorescence. Correlations were made between natural and artificial beachrocks. Results have shown that Diolkos beachrock was formed in the upper part of the intertidal zone, consisting of detrital material originating from the local bedrock, while Sumuide beachrock formed in the low intertidal–upper subtidal zone, consisting of coral sand and foraminifera fragments. For the artificial beachrocks, three samples were created using the microbial-induced carbonate precipitation (MICP) method, one from Diolkos (Corinth, Greece) and two from Sumuide (Okinawa, Japan). Diolkos artificial beachrock was better consolidated in comparison to Sumuide. Our investigation has shown that bacterial density was the key factor for the creation of the artificial beachrocks, while the samples’ granulometry played a secondary role in the process. The laboratory artificial beachrocks show encouraging results for a new soft engineering method to encounter beach erosion while keeping an ecofriendly character by saving energy, material resources and gas emissions. Artificial beachrocks can share the same properties of a natural beachrock and can contribute positively to marine biodiversity as a natural rocky habitat.

Geochronology and palaeoclimatic context of submerged siliciclastic beachrock formation in the western Mediterranean Sea

This article describes the geomorphological and petrological characteristics of 19 submerged beachrocks located on the north Catalan coast (western Mediterranean Sea). Their length ranges between 8 and 1039 m, their width between 1.5 and 86.5 m and their thickness between 0.4 and 3.25 m. They are siliciclastic beachrocks consisting of well-rounded gravels with a very coarse sand matrix, and they have a low proportion of bioclasts (<1%). Cementation occurred in the swash zone and adjacent foreshore due to the precipitation of high magnesium calcite. From absolute dates (14C and optically stimulated luminescence) and anthropic artifacts, three phases of formation attributable to the Late Holocene were identified. Phase I corresponds to the warm and humid Roman Period and was recorded at a level below -3.75 m mean sea level (MSL). Phase II corresponds to the warm and arid Medieval Climate Anomaly and was recorded at +0.25 m to -2.5 m MSL. Phase III corresponds to the Little Ice Age and Industrial Period and was recorded at levels ranging from +0.5 m to -3.0 m MSL. Good temporal correspondence between the chronology of the cementation phases and warm and/or dry palaeoclimatic conditions can be established.

A multi-analytical study of beachrock formation in Naxos and Paros Islands, Aegean Sea, Greece and their palaeoenvironmental significance

A multi-analytical study of beachrock formation in Naxos and Paros Islands, Aegean Sea, Greece and their palaeoenvironmental significance

IMPROVEMENT OF USING CRUDE EXTRACT UREASE FROM WATERMELON SEEDS FOR BIOCEMENTATION TECHNOLOGY

In recent years,the formation of artificial beachrock and bio-cementation method has gained considerable attention as a sustainable alternative tool in the area of geotechnical and geo-environmental engineering field for soil improvement and construction materials. In general, earlier methods of soil improvement were mostly concentrated on microbes (Bacteria, Fungi, etc.) as a source of urease enzyme widely known as MICP method (Microbial Induced Carbonate Precipitation). To address some of the keylimitations of MICP method this study focused on using crude enzyme (low cost, eco-friendly). Crude enzyme was extracted from watermelon seeds (Citrullus lanatus)considered as “food waste material” and the carbonate formation process known as EICP “Enzyme Induced Carbonate Precipitation.” Crushed and blended watermelon seeds (both dry and germinated) used as a source of urease enzyme. Subsequently, their urease activity was also investigated with various environmental parameters (Temperature, pH, etc.) and investigated the carbonate precipitation trend using calcium chloride (CaCl2) and urea [(CO(NH2)2]. The form of carbonate (calcite, aragonite, vaterite, etc.) was also confirmed by XRD and SEM-EDX analysis. Finally, syringe (d = 2.3 cm, h = 7.1 cm) sand solidification test was conducted using commercially available “Mikawa sand” (mean diameter, D50 = 870 mm) and successfully achieved unconfined compressive strength (UCS) of about 1.2 MPa at neutral pH (~7) and temperature condition (30 °C) considering various curing days and conditions. This study could be useful as an eco-friendly and sustainable method for numerous bio-geotechnical applications (for instance, ground improvement, liquefaction mitigation, artificial beach rock formations, coastal erosion protection, etc.) and the extracted crude urease from watermelon seeds could play as an alternative to replace commercially available urease for carbonate precipitation.

Cenozoic coastal carbonate deposits of Qatar: Evidence for dolomite preservation bias in highly‐arid systems

AbstractIn the ancient rock record, early replacement of metastable marine calcium carbonate deposits by dolomite has long been associated with evidence of arid depositional environments. Such associations led to the development of the seepage reflux dolomitization model, whereby magnesium‐rich marine waters concentrated by evaporation descend into underlying sediments, replacing primary aragonite and calcite deposits with dolomite through rock–water interaction. In the modern arid coastal systems of Qatar, where marine waters concentrate to halite saturation, both aqueous geochemical measurements and mineralogical investigations show that replacement of calcium carbonate deposits by dolomite is not occurring to any consequential degree. At best dolomite formation is minor and localized. Instead, modern and mid‐Holocene coastal deposits retain their original mineralogy, showing little evidence of carbonate precipitation reactions with the notable exception of beachrock formation. Pleistocene coastal deposits are mostly absent in comparison with both Qatar Holocene coastal deposits, and Pleistocene coastal deposits from more humid settings. The lack of onshore Pleistocene‐aged carbonate outcrops in Qatar, as well as regionally, is interpreted to reflect coastal sediment denudation during emergence due to: (i) the absence of coastal marine lithification; and (ii) the absence of meteoric cementation and root stabilization in the highly‐arid realm. In contrast, marine Palaeogene and Miocene carbonate deposits are preserved in outcrop in Qatar, having suffered marine lithification by dolomite, thus promoting retention of carbonate strata through subsequent lowstands. These older deposits formed during times of ocean acidification, which, based on natural system and laboratory investigations, is interpreted to promote metastable carbonate dissolution and dolomite formation. The highly‐arid Holocene and Pleistocene coastal systems of Qatar represent limestone factories, but these deposits are not being retained to the rock record. Based on these observations, the association between the occurrence of dolomite and arid depositional settings may be to some degree a preservation bias.

Beachrock as sea-level indicator – A case study at the coastline of Oman (Indian Ocean)

Future sea level changes are a threat to coastal communities worldwide. Therefore, reliable methods for the reconstruction of past relative sea-level variations are essential to make predictions of future developments. Beachrocks are a widely distributed indicator of Quaternary paleo-coastlines, with a high potential for preservation. Nevertheless, their use as sea-level indicator faces challenges in the determination of the exact elevation of beachrock formation with respect to paleo sea level. This information is crucial to the establishment of a sea-level index point.Our study area on the northeastern coastline of Oman shows a set of twelve marine terraces that reach a height of 500 m above mean sea level. While the upper terraces are erosional, the lowest three are depositional. On the erosional terraces beachrocks are the only sediment-cover that withstood erosion. On the depositional terraces however, beachrocks occur alongside other sediments, which can be fluvial, alluvial, or marine in origin. The coastal development of the area is of high interest as uplift and tectonic activity are ongoing.Fieldwork and petrographic methods on eight outcrops on three terrace levels led to the identification of eight lithofacies in six facies associations. We used facies analysis to improve the information on paleo sea level as derived by the sole use of geomorphological indicators. Here, we demonstrate that facies analysis (so far applied exclusively on sandy deposits) is applicable also to gravel-dominated systems. The results contribute to knowledge on local changes in the depositional environment and help to reconstruct uplift rates.

Rapid beachrock cementation on a South African beach: Linking morphodynamics and cement style

Rapid cementation (<5 years) of beachrock is reported from the wave-dominated, microtidal coastline of Durban, South Africa. The beachrock is developing at mean sea level on a steep (10°–30°), reflective beach prone to periodic erosion by high-energy wave action; the most recent erosional event resulted in retrogradation of the beach by up to 10 m landward of the beachrock outcrop discussed in this study. Transmitted light microscopy and scanning electron micrographs show the precipitation of two dominant cement types which are linked to the beachface morphodynamics. During the accreted beach phase, when the locus of beachrock formation lay well landward of the beachface in the undersaturated upper intertidal to supra tidal backbeach, meniscus cements were precipitated. Following a period of erosion, associated with a landward shift of the beachface, the incipient beachrock was then exposed to saturated conditions which promoted growth of acicular cements. Contemporary beachrock cementation occurred very rapidly (<5 years) between significant erosional events. The observed cement textures record short-term beach progradation and retrogradation but are similar to those typically associated with longer-term regression and transgression.

Diagenesis of Holocene Beachrock in Northeastern Brazil: Petrology, Isotopic Evidence and Age

This work aims to understand beachrock formation during Holocene through petrology, geochemistry and dating of a core located 5,43m deep in relation to present-day sea-level in the Piedade Beach in Jaboatao dos Guararapes- PE. The core is located 143 meters distant from the coast line towards mainland. Four lithofacies have been identified, taking into account differences in texture and sedimentary structures. The framework grain size ranges from medium to very coarse sand, indicating variations in depositional energy. Petrographic data indicate that the beachrocks have values of 64.23% to 70.69% of framework composed of quartz grains. Carbonate cement (represents 13.5%) consisting of high magnesium calcite surrounding grains as isopachous fringe (4.15% to 11.95%), micritic cement (0.60% to 6.42%) and equant cement (0.26% to 7.01%), indicates marine environment precipitation. The results of the isotopic composition of carbon and oxygen present valuesof 3.09‰ to 3.89‰, with an average of 3.63‰ to δ 13 C PDB and of -0.91‰ to 0.96‰, with an average of 0.54‰ to δ 18 O PDB, suggesting that the cement is formed in a shallow marine environment with freshwater influence. The values obtained in paleotemperature vary from 21oC to 30oC, with an average of 23oC, with little variation indicating precipitation in a shallow water environment. In the study area, the beachrocks are indicators of sea level and the results suggest that between 7.509 years B.P. and 5982 years B.P. there was a marine transgression process, with sea level 9.18 m lower than the current sea level.

Building biogenic beachrock: Visualizing microbially-mediated carbonate cement precipitation using XFM and a strontium tracer

The fate of reef islands is a topic of ongoing debate in the face of climate change-induced sea-level rise and increased cyclone intensity. Increased erosion and changes to the supply of reef-derived sediment may put sand reef cays at risk of dramatic morphological changes. These changes may have negative implications for the existence of reef cay environments, which host vital sea turtle and bird rookery habitats. Beachrock, consolidated carbonate beach sediment in the intertidal zone, forms naturally on many tropical beaches and reduces the erosion rates of these beaches when compared to unconsolidated sand. In spite of the critical role beachrock plays in stabilizing some reef cay shores, the method of beachrock formation is still incompletely understood. In this investigation, beachrock was synthesized using beach sand and beachrock samples from Heron Island (Great Barrier Reef, Australia) in aquarium experiments in which natural beachrock formation conditions were simulated. Beachrock was produced in two aquaria wherein the water chemistry was influenced by microorganisms derived from the natural beachrock ‘inoculum’, whereas no cementation occurred in an aquarium that lacked a microbial inoculum and was controlled only by physicochemical evapoconcentration. The new cements in the synthesized beachrock were analyzed using synchrotron-based X-ray fluorescence microscopy and were identified using a Sr-tracer added to the experimental seawater. The resulting precipitates cement sand grains together and contain abundant microfossils of the microorganisms on whose exopolymer they nucleated, demonstrating the fundamental role microbes play in beachrock formation. These results are of interest because beachrock could be utilized as a natural coastline stabilization strategy on sand reef cays, and in turn, protect the unique habitats reef islands support.

Beachrock formation via microbial dissolution and re-precipitation of carbonate minerals

Cementation of beach sand in the intertidal zone produces beachrock, such as that found on Heron Island (Heron Reef, Great Barrier Reef, Australia). Although common to coastlines in many low-latitude beach environments, the cause of cementation is not fully understood. In this investigation, electron and X-ray fluorescence microscopy were used to characterize previously undocumented features of beachrock. Two generations of beachrock were examined as a means of understanding the progression of cementation. Meniscus-shaped attachments at point contacts appear to be the first cements to form in biofilms near the beachrock surface. This is followed by isopachous fringe cements within the now ‘enclosed’ beachrock, composed of aragonite needles that are enriched in strontium and contain extracellular polymeric substances (EPS). Cement precipitation is driven by locally high concentrations of cations in solution, undoubtedly generated via microbial dissolution of the detrital carbonate grains. Binding to negatively charged bacterial EPS retains these cations within beachrock microenvironments. The metabolism of cyanobacteria and associated heterotrophs induce the supersaturating conditions needed for cement precipitation. Deeper within beachrock (mm to cm-below the surface), abundant microbialites are found on the edges of grains and contain trapped and bound detrital material. These structures are laminated, enriched in strontium in some layers, and contain microfossils. The results of this investigation clearly demonstrate a biological influence in the precipitation of aragonite cement involving internal recycling of cations through microbial dissolution and precipitation of carbonate minerals.

Carbonate sedimentary characteristics of the beach rocks around Qilian Islets and Cays, Xisha Islands: Implication for coral reef development and decline

Beach rocks, developed on the coast of Qilian Islets and Cays, Xisha Islands, China, represent carbonate sedimentary formation on a typical biogenic coast adjacent to coral reef areas. The subaerial and submarine distribution and natural outcrop sections of beach rocks around three islets were surveyed, traced, measured and mapped to determine their development and depositional successions. Carbonate sedimentary characteristics of the beach rocks show that more than 95% of sediments are sourced from adjacent reef flat and reef crest, and are dominated by reef-building coral skeletal fragments and detritus, calcareous algae, and other skeletal grains of reef dwellers. Bioclastic content, algal and microbial content, sorting and roundness of skeletal grains and porosity in depositional successions change with sediment source, sediment accumulation rate, grain characteristics and textures of sediments, hydrodynamic intensity and cementation features. Cementation of the beach rocks is characterized by the binding action of algae and microbes, the micritization caused by boring of endolithic algae and microbes, the early marine cementation, and the early meteoric cementation. Algal and microbial activity played a major role in micritization of skeletal grains of beach rocks. The beach rock formation is mainly affected by the algal and microbial content in beach sediments, the sediment supply from reef flat, the grain characteristics of beach sediments, cementation and diagenesis process, the hydrodynamic intensity driven by wind and monsoons, and sea-level changes. The developmental dimensions and spatial extent of coral reef architecture, the flourishing and extinction of reef-building organisms in reef ecosystem, the abundance of algae and microbes and the diversity of reef dwellers may influence wave energy dissipation and sediment transport patterns in reef flat, thus alter the carbonate sediment budget of the coastal environment.

Beachrock formation on the coast of Gökçeada Island and its relation to the active tectonics of the region, northern Aegean Sea, Turkey

There are beachrock formations in 5 different sections of the south coast of Gökçeada, Turkey's largest Aegean island. These beachrocks form two different groups in terms of layering characteristics, δ18O and δ13C stable isotope compositions, consecutive cementation structures, and 14C dating. The West Group beachrocks, to the west, were dated to 4010–5830 BP, while the East Group beachrocks were dated to 620–2390 BP. The beachrock formations in both groups are separated by the NE–SW-trending Uğurlu Fault. The Uğurlu Fault is a right lateral, strike slip with reverse component oblique fault, and is an active fault within the North Anatolian Fault Zone. In the period between the formation of the two beachrock groups (2390–4010 BP), an earthquake was responsible for the destruction of Gökçeada Yenibademli mound and the development of two generations of beachrock.

Formation of artificial beachrock towards inhibit of coastal erosion in Bangladesh: a review

Formation of artificial beachrock towards inhibit of coastal erosion in Bangladesh: a review

Microbially Induced Sand Cementation Method Using &lt;i&gt;Pararhodobacter&lt;/i&gt; sp. Strain SO1, Inspired by Beachrock Formation Mechanism

Microbially Induced Sand Cementation Method Using &lt;i&gt;Pararhodobacter&lt;/i&gt; sp. Strain SO1, Inspired by Beachrock Formation Mechanism

Vertical land movements and sea level changes along the coast of Crete (Greece) since Late Holocene

Geomorphological survey along the coasts of Crete revealed widespread evidence of uplifted and submerged tidal notches, different phases of beachrock formation, and many relics of ancient coastal constructions. About 1.6 ka BP, when the sea level was at −1.25 ± 0.05 m, the western tectonic block of the island uplifted by 9.15 ± 0.20 m in its westernmost extremity and by 2.00 m approximately in its eastern boundary and tilted southeastward. Repeated preceding episodes of subsidence submerged the western part of the island by 1.60 m in a period of 2300 years. Along the western coast, the younger phase of the submerged beachrocks was identified and measured at nineteen locations, together with the submerged tidal notches and archaeological remains. Land subsidence by 1.25 ± 0.05 m, subsequent to the uplift of the western part, occurred after the late Venetian occupation period (∼AD 1600), coincident with the submersion of the eastern part of the island.In central and eastern Crete, the relative sea level change evidence from tidal notches and beachrocks revealed five distinct sea level stands at −6.55 ± 0.55 m, −3.95 ± 0.35 m, −2.70 ± 0.15 m, −1.25 ± 0.05 m and −0.55 ± 0.05 m. The lowest sea level stand can be identified with the oldest dated tidal notch of western Crete between 4200 ± 90 B P and 3930 ± 90 B P. Two subsequent sea levels can be linked with the Protopalatial (1900–1700 B C or 1600 B C) and Neopalatial period (1600–1450 B C) of the Minoan civilization, according to submerged prehistoric morphologies and inundated Minoan constructions. The change of sea level from −2.70 ± 0.15 m to −1.25 ± 0.05 m is placed between 1450 B C and the fourth century BC. The dating of −1.25 ± 0.05 m sea level stand was based on the measurement and interpretation of ancient coastal installations built along the coast of central and eastern Crete during Classical, Hellenistic, Roman, Byzantine and Venetian periods. Historical sources report a relative sea level rise by 0.70 m during the AD 1604 paroxysmal event. Over the last 400 years, the relative sea level rose by 0.55 m. The uplift of the coast of western Crete and the submersion in its central and eastern coast indicate that during the AD 365 paroxysmal event the island was split along a tectonic boundary identified with the neotectonic graben of Spili and its northern and southern prolongation.

Focused ultrasound solid–liquid extraction for the determination of organic biomarkers in beachrocks

Beachrocks are consolidated coastal sedimentary formations resulting mainly from the relative rapid cementation of beach sediments by different calcium carbonate polymorphs. Although previous works have already studied the elemental composition and the mineral phases composing these cements, few of them have focused their attention on the organic matter present therein. This work describes an extraction methodology based on focused ultrasound solid–liquid extraction (FUSLE), followed by analysis using large volume injection (LVI) in a programmable temperature vaporizer (PTV) combined with gas chromatography–mass spectrometry (GC–MS) in order to determine organics such as polycyclic aromatic hydrocarbons (PAHs) and biomarkers (hopanes), which can increase and confirm the information obtained so far. This goal has been achieved after the optimization of the main parameters affecting the extraction procedure, such as, extraction solvent, FUSLE variables (amplitude, extraction time and pulse time) and also variables affecting the LVI–PTV (vent time, injection speed and cryo-focusing temperature). The developed method rendered results comparable to traditional extraction methods in terms of accuracy (77–109%) and repeatability (RSD<23%). Finally, the analyses performed over real beachrock samples from the Bay of Biscay (Northern Spain) revealed the presence of the 16 EPA priority PAHs, as well as some organic biomarkers which could increase the knowledge about such beachrock formation.