A Novel Method for Calcium Carbonate Deposition in Wood That Increases Carbon Dioxide Concentration and Fire Resistance

In this study, a novel method for calcium carbonate deposition in wood that increases carbon dioxide concentration and fire resistance is proposed. The method promoted the mineralization of radiata pine wood microstructure with calcium carbonate by using a process consisting in the vacuum impregnation of wood with a calcium chloride aqueous solution and the subsequent sequential diffusion of gaseous ammonium and carbon dioxide. In the most favorable conditions, the method yielded a weight gain of about 20 wt.% due to mineralization, which implied the accumulation of 0.467 mmol·g−1 of carbon dioxide in the microstructure of wood. In addition, a weight gain of about 8% was sufficient to provide fire resistance to a level similar to that achieved by a commercially available fire-retardant treatment. The feasibility of retaining carbon dioxide directly inside the wood microstructure can be advantageous for developing wood products with enhanced environmental characteristics. This method can be a potential alternative for users seeking materials that could be effective at supporting a full sustainable development.

Crust Biometry of Hydrolithon Boreale (Rhodophyta: Hydrolithaceae) on Leave of Posidonia Oceanica Along a Mediterranean Coast Fed by Siliciclastic-Carbonate

A study was conducted to estimate biometry of an epiphytic micro-calcareous red algae, Hydrolithon boreale found on leaves of a Mediterranean meadow, Posidonia oceanica along the entire Turkish coast of the Mediterranean Sea in time (winter and summer 2019) and space (regions, and bottom type and depth). Percent occurrence of the epiphyte was lower in winter (25%), particularly found in a small bay in the west than summer (44%), entirely along the coast. The epiphyte grew up to 5 mm in diameter, 0.35 mm in thickness of the crust size, and was populated up to 1006 ind/m2 in summer owing to the increased utilization of the carbonate by the epiphyte with the increased water temperature. The size was contrasted to the density (abundance and biomass) in space. The biometry was significantly dependent on the siliciclastic-carbonate deposition as inferred from SiO2 of the water in relation the leaf area index (LAI) of P. oceanica. Therefore, this deposition induced specimens growing in size, followed by the reduced density in relation to N-based nutrient of the water. Further major environmental parameters which negatively affected the biometry were pH and total suspended matter of the water, analogous to the turbidity. Of the trace elements, Ni was negatively correlated with the biometry whereas the LAI was however positively correlated with all the anthropogenic-sourced trace elements (V, Cu, Zn, As, Cd, and Pb) in the leaves. Of the bottom types, the calcite rock had higher density than the other soft bottoms in contrast to the size of the epiphyte.

Prediction and Early Detection of Karsts—An Overview of Methods and Technologies for Safer Drilling in Carbonates

The nature of carbonate deposition as well as diagenetic processes can cause the development of unique geological features such as cavities, vugs and fractures. These are called karsts. Encountering karsts while drilling can lead to serious consequences such as severe mud losses, drops of bottom hole assembly and gas kicks. To improve drilling safety in intervals of karstification, it is important to detect karsts as early as possible, preferably in advance. In this paper, we review methods and technologies that can be used for the prediction and early detection of karsts. In particular, we consider acoustic, resistivity, seismic and drilling-data methods. In addition to the inventions and technologies developed and published over the past 40 years, this paper identifies the advantages, limitations and gaps of these existing technologies and discusses the most promising methods for karst detection and prediction.

Ordovician and Mississippian stratigraphy in southwestern Missouri, USA

ABSTRACT A succession of Ordovician and Mississippian carbonates, separated unconformably, is exposed across the southern flank of the Ozark Dome in southwest Missouri. Deposits of both periods exemplify typical facies of the Midwestern United States: carbonate tidal-flat assemblages for the Early Ordovician and carbonate shelf environments for the Early–Middle Mississippian. The basic stratigraphic sequence of these deposits has been known for over a century, but interesting features remain to be addressed. Thin discontinuous sandstones are present within the Early Ordovician Cotter Dolomite, but the informal Swan Creek sandstone member seems anomalous. This sandstone can exceed 5 m in thickness and is fairly continuous across southwest Missouri. Most Ordovician sandstones in Missouri mark major transgressions above regional unconformities, but not the Swan Creek, and there is no obvious source of the sand. Therefore, we hypothesize that the Swan Creek represents reworked eolian dunes blown across the broad peritidal environment. Clastic sandstone dikes, apparently sourced from the Swan Creek, cut across beds of Cotter Dolomite near faults. We propose that these dikes are evidence of local faulting and seismicity during the Early Ordovician. Early and Middle Mississippian limestones comprise a sequence of shelf deposits, although mud mounds and other facies changes near the Missouri-Arkansas line mark the edge of the Mississippian shelf and the transition to a ramp setting. Early Mississippian carbonate deposition was interrupted by a short and localized influx of siliciclastic sediment comprising the Northview Formation. The Northview has additional characteristics consistent with a river-dominated deltaic deposit, which we suggest as its origin. If correct, this hypothesis implies that the history of tectonic features in the Midwest is more complicated than yet known. Finally, facies changes within and between the local Mississippian formations may record an early crustal response to the impending Ouachita orogeny farther to the south.

Calcium Transport along the Axial Canal in Acropora

In Acropora, the complex canals in a coral colony connect all polyps to a holistic network, enabling them to collaborate in performing biological processes. There are various types of canals, including calice, axial canals, and other internal canals, with structures that are dynamically altered during different coral growth states due to internal calcium transport. In this study, we investigated the morphological changes in the corallite of six Acropora muricata samples by high resolution micro-computed tomography, observing the patterns of calcium carbonate deposition within axial corallite during processes of new branch formation and truncated tip repair. We visualized the formation of a new branch from a calice and the calcium carbonate deposition in the axial canal. Furthermore, the diameter and volume changes of the axial canal in truncated branches during rebuilding processes were calculated, revealing that the volume ratio of calcareous deposits in the axial canal exhibit significant increases within the first three weeks, returning to levels in the initial state in the following week. This work demonstrates that calcium carbonate can be stored temporarily and then remobilized as needed for rapid growth. The results of this study shed light on the control of calcium carbonate deposition and growth of the axial corallite in Acropora.

The Late Jurassic–Palaeogene Carbonate Platforms in the Outer Western Carpathian Tethys—A Regional Overview

The present work focuses on palaeogeographic reconstruction of shallow-water carbonate deposition in the Outer Western Carpathian Tethys. Platform deposits are preserved only as a component of turbidites and olistostromes, and reconstructions of these platforms are based on clastic material redistributed into slopes and deep basins and occurring among the Outer Carpathian nappes. Similar platforms were also present on the Tethys margins. These reconstructions were performed using the global models of plate tectonics. Several ridges covered by carbonate platforms developed in that area during the latest Jurassic–Palaeogene times. Three main shallow-water facies associations—Štramberk, Urgonian, and Lithothamnion–bryozoan—could be distinguished. The Tithonian–lowermost Cretaceous Štramberk facies is related to early, synrift–postrift stage of the development of the Silesian Domain. Facies that are diversified, narrow, shallow-water platforms, rich in corals, sponges, green algae, echinoderms, foraminifera, microencrusters, and microbes are typical of this stage. The Urgonian facies developed mainly on the south margin of the Outer Carpathian basins and is characterised by organodetritic limestones built of bivalves (including rudists), larger benthic foraminifera, crinoids, echinoids, and corals. Since the Paleocene, in all the Western Outer Carpathian sedimentary areas, Lithothamnion–bryozoan facies developed and adapted to unstable conditions. Algae–bryozoan covers originating on the siliciclastic substrate are typical of these facies. This type of deposition was preserved practically until the final stage in the evolution of the Outer Carpathian basins.

The carbonate compensation depth in the South Atlantic Ocean since the Late Cretaceous

Deep-sea carbonate deposition is a complex process that is encapsulated in the carbonate compensation depth (CCD)—a facies boundary separating calcareous sediments from non-carbonates. Knowing how the CCD has varied over time is important for understanding and predicting the distribution of seafloor sediments and assessing their role in the global carbon cycle. We focus on the South Atlantic Ocean where the most recent CCD curve is based on Deep Sea Drilling Project (DSDP) Leg 73 sites drilled in 1980 in the South Atlantic Ocean. We compute the South and central South Atlantic CCD from the Late Cretaceous to the present day using updated age models from 45 DSDP and Ocean Drilling Program sites and backtracking with lithology-specific decompaction, eustasy, and dynamic topography. Our models extend further back in time and show more fluctuations than previous reconstructions, with the CCD varying by hundreds of meters during a span of 2–3 m.y. The addition of eustasy and dynamic topography deepens the CCD by as much as 500 m between 74 Ma and 45 Ma, and by ~200 m during the Cenozoic. The central South Atlantic CCD diverges from the average South Atlantic CCD during the Eocene and Miocene, when it was ~1 km shallower. These regional deviations may be due to changes in primary productivity and/or carbonate dissolution leading to reduced carbonate accumulation rates. Our CCD curves highlight the importance of regional processes in carbonate deposition across the South Atlantic and provide improved constraints for the modeling of geochemical cycles.