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Benthic foraminifera, carbonate microfacies identification, and geochemical analysis of the Permian intervals of Pleshet-1 and David-1 boreholes from western Israel,-allowed a determination of their time frame and tectono-sedimentary relationships, further allowing insights about the nature and regional subsurface expression of the Permian. Carbonate horizons within the mixed lithology successions, yielded foraminifera suggesting the Middle/Late Permian transition. The carbonate microfacies and related stable isotopic profiles indicate a change from siliciclastic marginal marine conditions (Saad Fm.) to fully marine platform conditions (Arqov Fm.) in a gradual marine transgression onto a segmented peneplain, and producing sedimentary facies belts striking SW–NE. A comparison of this work with previous work in southern and eastern Israel suggests that the Permian formations in Israel formed NW to SE diachronistically, by marine transgression during the Middle and the Late Permian, with maximum flooding during the Changhsingian. It appears that although not precisely defined, the regional Middle/Late Permian transition happened during a major marine transgression, characterized by a negative to positive stable isotope shift, and by apparently gradual aridization of the hinterland. The regional onset of sedimentation occurred on a marginally superficially downfaulted northwestward peneplain, subdivided tentatively into four segments with shallow half-graben structures. The three eastern segments ceased their differential movements and maintained uniform northwestward subsidence during the late Wuchiapingian–Changhsingian. The most western fourth segment had differential fault activity through the Triassic and the Jurassic, and is proposed to be placed on a transition to a proximal tectonic necking zone. [ABSTRACT FROM AUTHOR]

The Eocene Large Benthic Foraminiferal limestones of the Tethyan margins are proven hydrocarbon reservoirs. This study examines the controls on porosity and permeability development of the producing Middle Eocene Pirkoh Member of the Eastern Tethys using well core data from Well Zx-01 from the Punjab Platform area, Central Indus Basin, Pakistan. The standard petrographic and core analysis techniques were adopted to determine these controls. Petrographic studies revealed three microfacies comprising bioclastic packstone to floatstone, bioclastic wackestone and mud-wackestone microfacies. The allochems belong to benthic foraminifera including Nummulites sp., Discocyclinids sp.., Coralline algae, Assilina sp., Lockhartia sp., Coralline algae and Gastropods along with the other bioclastic debris. These allochems were found embedded in the micritic matrix with extensive cementation of calcite. The diagenetic events included cementation, compaction, dolomitization, fracture filling and neomorphism. Based on microfacies, the environment of deposition is interpreted to be a high-energy zone of the middle ramp in shallow marine environment. Subsurface core indicates that the porosity of the reservoir is low to high ranging between 6 to 27.47% and permeability is found low to fair ranging between 0.03 to 7.73 mD, found closely related to microfacies and diagenetic modifications. This study is a first attempt to document the reservoir facies of the non-reefal carbonates of the Pirkoh limestone that would help to exploit the reservoir's potential of the carbonate platforms developed in similar settings worldwide. [ABSTRACT FROM AUTHOR]

The lithium (Li) isotopic composition of carbonates is considered to be a reliable archive of past seawater Li isotopic compositions, which are useful as a tracer of silicate weathering. However, δ7Li values have been shown to be dependent on either pH or DIC in two studies using similar species of large, benthic foraminifera from the genus Amphistegina. To resolve this issue, we conducted culture experiments on Amphistegina lessonii in decoupled pH–DIC conditions, under two different light treatments, and with normal or Li-enriched seawater. The δ7Li values and Li/Ca ratios in the foraminifera tests were analysed by ion microprobe and LA-ICP-MS, respectively. No links between either the pH or DIC and δ7Li or Li/Ca values were observed for any of the treatments, and growth rates also did not seem to influence the Li incorporation or isotopic fractionation, contrary to observations from inorganic carbonate-precipitation experiments. Overall, these findings appear to support the use of Li isotopes in large benthic foraminifera to reconstruct past seawater chemistry and to infer changes in chemical weathering during carbon-cycle perturbations. [ABSTRACT FROM AUTHOR]

Symbiont-bearing perforated large benthic foraminifers are vital to the formation of coral reef islands in the Pacific Ocean and are affected by the deterioration of reefal water quality in urbanized atolls. Recently, road traffic was identified as a notable source of heavy-metal pollution in the densely populated area of Majuro atoll in the Marshall Islands. However, the effects of polycyclic aromatic hydrocarbons (PAHs) on LBFs have not been investigated so far. In the present study, pyrene, a PAH, was selected, and its effects on photosynthesis were examined by using Calcarina gaudichaudii. The organisms were exposed to 0.02, 2.0, and 200 µg L−1 of pyrene for 8 d. The effective and maximum quantum yields did not change (p > 0.05). Chlorophyll-a content too remained constant (p > 0.05). The results indicate that pyrene does not damage the photosystem II and symbiotic algal cell in C. gaudichaudii. Although a previous study reported that the cell density of a marine diatom decreased on exposure to 125 µg L−1 of pyrene, the Langmuir adsorption isotherm model confirmed that pyrene was sufficiently adsorbed on the dried shell of C. gaudichaudii. Through visual observation, sticky materials such as the extracellular organic matrix around C. gaudichaudii were identified under exposure to pyrene. This extracellular organic matrix likely acted as a protective layer against the toxic effects of pyrene with different defense mechanisms found in coral. We conclude that C. gaudichaudii can tolerate short-term exposure to pyrene. [ABSTRACT FROM AUTHOR]

Large benthic foraminifera are an integral component of shallow-water tropical habitats and like many marine calcifiers, are susceptible to ocean acidification (OA) and ocean warming (OW). In particular, the prolific Symbiodiniaceae-bearing and high-magnesium calcite Marginopora vertebralis has a low threshold compared to several diatom-bearing and low-magnesium calcite species. In this multi-year mesocosm experiment, we tested three RPC 8.5 climate change scenarios (i) present day, (ii) the year 2050, and (iii) 2100. To enable a realistic epiphytic association, these experiments were uniquely conducted using natural carbonate substrate, living calcifying alga, and seagrass. In contrast to previous studies, we detected no reduction in surface-area growth under future climate conditions compared with present day conditions. In terms of calcification, M. vertebralis' epiphytic association to primary producers (i.e., calcifying algae and seagrasses) potentially ameliorates the effects of OA by buffering against declines in boundary layer pH during periods of photosynthesis (i.e., CO2 removal). Importantly for population maintenance, we observed a strong reduction in asexual fecundity under the 2100 scenario. We propose the additional energy needed to maintain growth might be one reason for drastically reduced asexual reproduction. An alternative explanation could be that the 2 °C temperature increase interfered with the environmental synchronization that triggered asexual multiple fission. We conclude that the low levels of reproduction will reduce populations in a high CO2 environment and reduce a valuable source of CaCO3 sediment production. [ABSTRACT FROM AUTHOR]

Foraminifera are highly diverse and have a long evolutionary history. As key bioindicators, their phylogenetic schemes are of great importance for paleogeographic applications, but may be hard to recognize correctly. The phylogenetic relationships within the prominent genus Amphistegina are still uncertain. Molecular studies on Amphistegina have so far only focused on genetic diversity within single species and suggested a cryptic diversity that demands for further investigations. Besides molecular sequencing-based approaches, different mass spectrometry-based proteomics approaches are increasingly used to give insights into the relationship between samples and organisms, especially as these do not require reference databases. To better understand the relationship of amphisteginids and test different proteomics-based approaches we applied de novo peptide sequencing and similarity clustering to several populations of Amphistegina lobifera, A. lessonii and A. gibbosa. We also analyzed the dominant photosymbiont community to study their influence on holobiont proteomes. Our analyses indicate that especially de novo peptide sequencing allows to reconstruct the relationship among foraminiferal holobionts, although the detected separation of A. gibbosa from A. lessonii and A. lobifera may be partly influenced by their different photosymbiont types. The resulting dendrograms reflect the separation in two lineages previously suggested and provide a basis for future studies. [ABSTRACT FROM AUTHOR]

One hundred and forty‐four published successions of shallow‐water carbonates, deposited between the Palaeocene and the Miocene, from the Levant to the Himalayas, have been re‐analysed using a standardised approach to investigate the distribution of carbonate facies and carbonate‐producing organisms. Large benthic foraminifera were found to be the volumetrically most important group of carbonate producers during the whole period, with a peak in abundance during the Eocene. Colonial corals are relatively abundant during the Palaeocene and Miocene, their abundance peaks during the Oligocene and has a minimum during the Eocene. Red calcareous algae have a similar pattern although their peak in abundance covers both the Oligocene and Miocene. Green calcareous algae decrease from the Palaeocene onward. Facies related to very shallow and/or restricted marine conditions peak during the Miocene and in particular during the Aquitanian. Both the pattern of large benthic foraminifera and of colonial corals seems to be related to temperature, with warm periods favouring the former group and cool periods the latter group. Red calcareous algae display a pattern similar to that of colonial corals suggesting that the periods favourable for one group are, on a large scale, also favourable for the other. The progressive decrease of green calcareous alga could be tentatively related to a preservation bias connected to the transition from Palaeogene assemblages that included presumably calcitic taxa of green algae to Neogene assemblages entirely constituted by aragonitic taxa with limited preservation potential. The Aquitanian peak in facies related to very shallow and/or restricted marine conditions is most likely connected to the progressive narrowing of the Tethys related to the collision between Arabia and Eurasia. These results denote an overall agreement between the abundance of the various types of shallow‐water carbonate facies and large‐scale environmental and geological processes, highlighting the potential for palaeoenvironmental reconstruction locked in the shallow‐water record. [ABSTRACT FROM AUTHOR]

Coral reefs are in global decline and anomalously hot temperatures shoulder the blame. Foraminferal bioindicators are important because they record historical reef stress over periods of centuries to millennia, as compared to the few decades offered by diver surveys. For a region lacking systematic long-term reef monitoring programs, the use of bioindicators in the Red Sea is compelling. Whereas foraminfera-based indices exist to reconstruct histories of nutrient stress on reefs, there is a paucity of equivalent bioindicators that respond to temperature. Capitalizing on a portfolio of surficial sediment samples collected along the eastern margin of the N. Red Sea and Gulf of Aqaba, this study shows that the relative abundance of Amphisteginidae foraminifera—specifically Amphistegina lobifera—closely track heat stress, as has recently been reported for this family in the S. Pacific. This result is consequential for at least three reasons. First, the Red Sea hosts some of the most northerly coral reefs on Earth. Establishment of a thermal bioindicator here confirms the strategy can be deployed on high latitudes reefs, which are disproportionally afflicted with heat extremes. Second, the considered reefs, and the foraminifera they host, are famed for their thermal resilience. Foraminiferal bioindicators have not previously been trialed on reefs that have adapted in this way. Finally, as a restricted offshoot of the Indian Ocean, the level of endemism in the Red Sea is especially high. The bioindicator that we propose is apparently not compromised by endemism. Our findings advocate for an expanded deployment of Amphistegina-based reef bioindicators. [ABSTRACT FROM AUTHOR]

The accelerated release of heavy metals into the coastal environments due to increasing anthropogenic activities poses a severe threat to local marine ecosystems and food chains. Although some heavy metals are essential nutrients for plants and animals, higher concentrations can be toxic and hazardous. To mitigate this threat, developing quantifiable proxies for monitoring heavy metal concentrations in near-shore marine environments is essential. Here, we describe culture experiments to quantify uptake of some heavy metals using live juvenile specimens of the large benthic foraminifera (LBF) Amphisorus hemprichii collected from the subtropical waters of Rottnest Island located ~20 km offshore Perth, South West Australia. The uptake of Mn, Ni, Cd, and Pb in the newly precipitated chambers of Amphisorus hemprichii in the laboratory was characterized using the micro-analytical technique, laser ablation inductively coupled plasma mass spectrometry. We found no significant increase in Mn, Ni, Cd, and Pb incorporation in the tests of Amphisorus hemprichii with increasing temperature and light intensities. Importantly, we found that changes in the concentrations of Mn, Ni, and Cd in the A. hemprichii tests are directly proportional to those in the culture solution over a wide range of concentrations. The calculated partition coefficients for Mn, Ni, and Cd from our culture experiments are 1.3±0.2, 0.3±0.04, 2.6±0.3, respectively. These multi-element calibration studies now enable A. hemprichii to be utilized as a naturally occurring bio-archive to quantitatively monitor the anthropogenic pollution of Mn, Ni, and Cd in coastal waters. [ABSTRACT FROM AUTHOR]

Global warming permits range expansions of tropical marine species into mid-latitude habitats, where they are, however, faced with cold winter temperatures. Therefore, tolerance to cold temperatures may be the key adaptation controlling zonal range expansion in tropical marine species. 2. Here we investigated the molecular and physiological response to cold and heat stress in a tropical symbiont-bearing foraminifera that has successfully invaded the Eastern Mediterranean. 3. Our physiological measurements indicate thermal tolerance of the diatom symbionts but a decrease in growth for the foraminifera host under both cold and warm stress. 4. The combined ('holobiont') transcriptome revealed an asymmetric response in short-term gene expression under cold versus warm stress. Cold stress induced major reorganization of metabolic processes, including regulation of genes involved in photosynthesis. Analyses limited to genes that are inferred to belong to the symbionts confirm that the observed pattern is due to changes in the regulation of photosynthesis-related genes and not due to changes in the abundance of the symbionts. 5. In contrast to cold stress, far fewer genes change expression under heat stress and those that do are primarily related to movement and cytoskeleton. This implies that under cold stress, cellular resources are allocated to the maintenance of photosynthesis, and the key to zonal range shifts of tropical species could be the cold tolerance of the symbiosis. [ABSTRACT FROM AUTHOR]

In tropical and sub‐tropical mixed siliciclastic–carbonate depositional systems, fluvial input and in situ neritic carbonate interact over space and time. Despite being the subject of many studies, controls on partitioning of mixed sediments remains controversial. Mixed sedimentary records, from Ashmore Trough shelf edge and slopes (southern Gulf of Papua), are coupled with global sea‐level curves and anchored to Marine Isotope Stage stratigraphy to constrain models of sediment accumulation at two different timescales for the past 130 kyr: (i) 100 kyr scale for last glacial cycle; and (ii) millennial scale for last deglaciation. During the last glacial cycle, carbonate production and accumulation were primarily controlled by sea‐level fluctuations. Export of neritic carbonate to the slopes was initiated during re‐flooding of previously exposed reefs and continued during Marine Isotope Stage 5e and 1 interglacial sea‐level highs. Siliciclastic fluxes to the slope were controlled by interplay of sea level, shelf physiography and oceanic currents. Heterogeneous accumulation of siliciclastic mud on the slope, took place during Marine Isotope Stage 5d to Marine Isotope Stage 3 sea‐level fall. Siliciclastics reached adjacent depocentres during Marine Isotope Stage 2. Coralgal reef and oolitic–skeletal sand resumed at the shelf edge during the subsequent stepwise sea‐level rise of the last deglaciation. Contemporaneous, abrupt siliciclastic input from increased precipitation and fluvial discharge illustrates that climate controlled deglacial sedimentation. Siliciclastic input persisted until ca 8.5 ka. Carbonate accumulation waned at the shelf edge after ca 14 ka, whereas it increased on the slopes since ca 11.5 ka, when previously exposed reef and bank tops were re‐flooded. When comparing the last sea‐level cycle sedimentation patterns of the southern Gulf of Papua with other coeval mixed systems, sea level and shelf physiography emerge as primary controls on deposition at the 100 kyr scale. At the millennial scale, siliciclastic input was also controlled by climate change during the unstable atmospheric and oceanic conditions of the last deglaciation. [ABSTRACT FROM AUTHOR]

Concurrent anthropogenic global climate change and ocean acidification are expected to have a negative impact on calcifying marine organisms. While knowledge of biological responses of organisms to oceanic stress has emerged from single‐species experiments, these do not capture ecologically relevant scenarios where the potential for multi‐organism physiological interactions is assessed. Marine algae provide an interesting case study, as their photosynthetic activity elevates pH in the surrounding microenvironment, potentially buffering more acidic conditions for associated epiphytes. We present findings that indicate increased tolerance of an important epiphytic foraminifera, Marginopora vertebralis, to the effects of increased temperature (±3°C) and pCO2 (~1,000 µatm) when associated with its common algal host, Laurencia intricata. Specimens of M. vertebralis were incubated for 15 days in flow‐through aquaria simulating current and end‐of‐century temperature and pH conditions. Physiological measures of growth (change in wet weight), calcification (measured change in total alkalinity in closed bottles), photochemical efficiency (Fv/Fm), total chlorophyll, photosynthesis (oxygen flux), and respiration were determined. When incubated in isolation, M. vertebralis exhibited reduced growth in end‐of‐century projections of ocean acidification conditions, while calcification rates were lowest in the high‐temperature, low‐pH treatment. Interestingly, association with L. intricata ameliorated these stress effects with the growth and calcification rates of M. vertebralis being similar to those observed in ambient conditions. Total chlorophyll levels in M. vertebralis decreased when in association with L. intricata, while maximum photochemical efficiency increased in ambient conditions. Net production estimates remained similar between M. vertebralis in isolation and in association with L. intricata, although both production and respiration rates of M. vertebralis were significantly higher when associated with L. intricata. These results indicate that the association with L. intricata increases the resilience of M. vertebralis to climate change stress, providing one of the first examples of physiological buffering by a marine alga that can ameliorate the negative effects of changing ocean conditions. [ABSTRACT FROM AUTHOR]

Copyright of Ameghiniana is the property of Argentine Paleontological Association / Asociacion Paleontologica Argentina and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Understanding the role of dispersal and adaptation in the evolutionary history of marine species is essential for predicting their response to changing conditions. We analyzed patterns of genetic differentiation in the key tropical calcifying species of large benthic foraminifera Amphistegina lobifera to reveal the evolutionary processes responsible for its biogeographic distribution. We collected specimens from 16 sites encompassing the entire range of the species and analyzed hypervariable fragments of the 18S SSU rDNA marker. We identified six hierarchically organized genotypes with mutually exclusive distribution organized along a longitudinal gradient. The distribution is consistent with diversification occurring in the Indo‐West Pacific (IWP) followed by dispersal toward the periphery. This pattern can be explained by: (a) high dispersal capacity of the species, (b) habitat heterogeneity driving more recent differentiation in the IWP, and (c) ecological‐scale processes such as niche incumbency reinforcing patterns of genotype mutual exclusion. The dispersal potential of this species drives the ongoing range expansion into the Mediterranean Sea, indicating that A. lobifera is able to expand its distribution by tracking increases in temperature. The genetic structure reveals recent diversification and high rate of extinction in the evolutionary history of the clade suggesting a high turnover rate of the diversity at the cryptic level. This diversification dynamic combined with high dispersal potential, allowed the species to maintain a widespread distribution over periods of geological and climatic upheaval. These characteristics are likely to allow the species to modify its geographic range in response to ongoing global warming without requiring genetic differentiation. [ABSTRACT FROM AUTHOR]

Copyright of Geologické Práce Správy is the property of State Geological Institute of Dionyz Stur and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Adaptation, acclimatization and symbiont diversity are known to regulate thermal tolerance in corals, but the role of these mechanisms remains poorly constrained in other photosymbioses, such as large benthic foraminifera (LBFs), which are known to bleach at temperatures that are likely to be exceeded in the near future. LBFs inhabit a broad range of shallow-water settings. Within species, differences in thermal tolerance have been found among populations from different habitats, but it is not clear whether such differences occur among LBFs inhabiting similar habitats, but differing in other aspects, such as symbiont type. To this end, we compared responses to thermal stress in specimens from a population of Amphistegina lessonii, an abundant Indo-Pacific species, to specimens of Amphistegina gibbosa, its Atlantic counterpart, from a similar environment but two different water depths (5 and 18 m). Test groups of each species were exposed in a common experiment to three thermal stress scenarios over a four-week period. Growth, respiration, mortality and motility were measured to characterize the holobiont response. Coloration, photosynthesis and chlorophyll a content were measured to determine the response of the endosymbiotic diatoms. The photosymbionts were characterized by genetic fingerprinting. Our results show that, although groups of A. gibbosa were collected from different habitats, their responses were similar, indicating only marginally higher tolerance to thermal peaks in specimens from the shallower site. In contrast, species-specific differences were stronger, with A. lessonii showing higher tolerance to episodic stress and less pronounced impacts of chronic stress on motility, growth and photosymbiont performance. These interspecies variations are consistent with the presence of different and more diverse symbiont assemblages in A. lessonii compared with A. gibbosa. This study demonstrates the importance of considering symbiont diversity in the assessment of intra- and interspecific variations in stress responses in LBFs. [ABSTRACT FROM AUTHOR]

Fellowes, T.E.; Gacutan, J.; Harris, D.L.; Vila-Concejo, A.; Webster, J.M., and Byrne, M., 2017. Patterns of sediment transport using foraminifera tracers across sand aprons on the Great Barrier Reef. Sediment dynamics exert large control over coral reef geomorphological evolution and are vital to understanding past and present geomorphic responses. Large benthic foraminifera (LBF) live in the algal reef flats, and their tests (shells) are transported post-mortem by waves and currents onto back-reef environments, including sand aprons. This study investigated the patterns of transport linking surficial and downcore sediments in samples from three sand aprons with different wave exposures at One Tree Reef on the southern Great Barrier Reef (Australia). Six LBF genera represented up to 32% of the sediments analysed. Lagoonward transport increased LBF test abrasion and sediment bulk density. Sediment grain size and LBF abundance in sediments also decreased with lagoonward transport. Sediment transport patterns indicated by LBF species used as tracer were consistent with the prominent E-SE wave environment. A novel taphofacies approach was used to describe stratigraphic layers in downcore sediments based on LBF test abrasion and abundance. Varied sediment deposition rates did not affect the LBF test abrasion signature downcore. It appears that Baculogypsina sphaerulata has been the dominant species for at least 3 ka. Tests that were deposited slowly exhibited less or the same levels of abrasion than those that were rapidly deposited. It appears that test abrasion is primarily determined by the distance travelled rather than the influence of increased age or chemical dissolution. [ABSTRACT FROM AUTHOR]

Large benthic foraminifera (LBF) are prolific producers of calcium carbonate sediments in shallow, tropical environments that are being influenced by ocean acidification (OA). Two LBF species, Amphistegina gibbosa (Order Rotaliida) with low-Mg calcite tests and Archaias angulatus (Order Miliolida) with high-Mg calcite tests, were studied to assess the effects of pH 7.6 on oxygen and carbon isotopic fractionation between test calcite and ambient seawater. The δ18O and δ13C values of terminal chambers and of whole adult tests of both species after 6 weeks were not significantly different between pH treatments of 8.0 and 7.6. However, tests of juveniles produced during the 6-week treatments showed significant differences between δ18O and δ13C values from control (pH 8.0) when compared with the treatment (pH 7.6) for both species. Although each individual's growth was photographed and measured, difficulty in distinguishing and manually extracting newly precipitated calcite from adult specimens likely confounded any differences in isotopic signals. However, juvenile specimens that resulted from asexual reproduction that occurred during the experiments did not contain old carbonate that could confound the new isotopic signals. These data reveal a potential bias in the design of OA experiments if only adults are used to investigate changes in test chemistries. Furthermore, the results reaffirm that different calcification mechanisms in these two foraminiferal orders control the fractionation of stable isotopes in the tests and will reflect decreasing pH in seawater somewhat differently. [ABSTRACT FROM AUTHOR]

Large benthic foraminifera (LBFs) are a vital component of coral reef carbonate production, often overlooked due to their small size. These super-abundant calcifiers are crucial to reef calcification by generation of lagoon and beach sands. Reef-scale carbonate production by LBFs is not well understood, and seasonal fluctuations in this important process are largely unquantified. The biomass of five LBF species in their algal flat habitat was quantified in the austral winter (July 2013), spring (October 2013), and summer (February 2014) at One Tree Reef. WorldView-2 satellite images were used to characterize and create LBF habitat maps based on ground-referenced photographs of algal cover. Habitat maps and LBF biomass measurements were combined to estimate carbonate storage across the entire reef flat. Total carbonate storage of LBFs on the reef flat ranged from 270 tonnes (winter) to 380 tonnes (summer). Satellite images indicate that the habitat area used by LBFs ranged from 0.6 (winter) to 0.71 km (spring) of a total possible area of 0.96 km. LBF biomass was highest in the winter when algal habitat area was lowest, but total carbonate storage was the highest in the summer, when algal habitat area was intermediate. Our data suggest that biomass measurements alone do not capture total abundance of LBF populations (carbonate storage), as the area of available habitat is variable. These results suggest LBF carbonate production studies that measure biomass in discrete locations and single time points fail to capture accurate reef-scale production by not incorporating estimates of the associated algal habitat. Reef-scale measurements in this study can be incorporated into carbonate production models to determine the role of LBFs in sedimentary landforms (lagoons, beaches, etc.). Based on previous models of entire reef metabolism, our estimates indicate that LBFs contribute approximately 3.9-5.4% of reef carbonate budgets, a previously underappreciated carbon sink. [ABSTRACT FROM AUTHOR]

The Late Eocene-Oligocene-Early Miocene sequences of the Kurdistan foreland basin, considered as an important shallow, thick oil and gas reservoir in Kurdistan region/N-Iraq. Several diverse larger foraminifera ( Alveolina, Orbitolites, Assilina, Archaias, Austrotrillina, Miogypsinoide, Nummulites, Operculina, Borelies, and Lepdicyclina) with important stratigraphic, paleo-ecological, and palaeo-biogeographical implications are described with respect to its position in the Neo-Tethys basin. The biozonation, using large benthonic foraminifera, leads to the reconstruction of the chronostratigraphic framework. For that purpose, more than 367 samples from six wells and twelve outcrops, from different tectonic domains, within Zagros fold-thrust belt were analyzed. Almost four sequence boundaries (SB) segmented the depositional sequences into three third-order sequences. The lower most sequence boundary was estimated to be of Bartonian age (37 Ma) that represents by more than 5-m conglomerates between the molasses facies of the Gercus and carbonates of the Pila Spi Formations. The second sequence boundary, known as Zagros Major Hiatus, was estimated to be of the age 34 Ma and was placed at the top of karstfied carbonates of the Pila Spi Formation (Pribonian), directly below the Fatha Formation (Burdigalian-Langhian) almost manifesting the boundary between Tectonomegasequence AP10 and AP11. The third one is almost between the Rupelian and the Chattian (28 Ma) within Kirkuk Group. The last recorded one of Aquitanian age (21 Ma) was placed between the Kirkuk Group and Jeribe or Euphrates Formations. The three third-order depositional sequences were recognized from deepening and shallowing trends in the depositional facies, stacking patterns, and sequence boundary features. The first third-order represents the Late Eocene sequence (Pila Spi-shelf facies latterly change to Avanah-Jaddala Formations-depocenter facies), the second one represents the Rupelian-Chattian-Early Aquitanian third order in which each of the lower cycle of the Kirkuk Group (Rupelian) and the upper sequence of the Kirkuk Group (Chattian-Early Aquitanian) represents a fourth-order sequence. The last third order manifests by the Late Aquitanian-Early Burdigalian sequence of the Euphrates shelf facies that is changed laterally to Serikagni depocenter facies and mostly change upwards to Jeribe Formation. The lateral and vertical facial changes point to the increasing of the sequence thicknesses from the high folded thrust zone towards the low folded thrust zone and across the transversal Khanqain fault. The carbonate depositional ramp mostly segmented into isolated highs (occasionally separated from the palaeo-shorelines), that are either due to the influence of the thrust propagation deformational front or reactivation of the deep cited faults. [ABSTRACT FROM AUTHOR]

The Ziyarat Formation is a Late Paleocene to Middle Eocene carbonate sequence, located in the north of Tochal Village (south-east of Tehran). The Ziyarat Formation with a total thickness of 212.5 m conformably overlies the Fajan conglomerate and is overlain by greenish tuffaceous siltstone of the Karj Formation. Petrographic studies have led to the recognition of 11 microfacies. Of these microfacies, five belong to inner ramp, four belong to middle ramp and two are located in the outer ramp. Due to the great diversity and abundance of large benthic foraminifera (e.g., Nummulites, Alveolina, Discocyclina), the Ziyarat Formation represents an example of 'foraminifera-dominated carbonate ramp settings'. Paleobathymetry, light level and water energy were determined during deposition of Ziyarat carbonates based on the test shape and size variation of different types of benthic foraminifera and other components in different facies. Micritization, cementation, compaction, dissolution, dolomitization and fracturing are important diagenetic processes in the Ziyarat Formation, occurring in marine to meteoric and burial diagenetic environments. Geochemical studies indicate that Ziyarat carbonates were deposited in a shallow warm-water sub-tropical environment and aragonite was the original carbonate mineralogy with mean Sr values of 3,470 ppm. It should be noted that the maximum Sr content in abiotic calcite is 1,000 ppm. In Ziyarat limestone, dissolution as leaching is the most important diagenetic event in the evolution of porosity, particularly where Nummulite and other benthic foraminifera are abundant. This may indicate that the original carbonate mineralogy of Nummulites might be aragonite, rather than low-Mg calcite. In the Jahrum Formation of Iran and in the El Garia Formation in north-east of Libya, the widespread moldic porosity in Nummulite beds enhanced the reservoir potential of the carbonate sequence. Thus, it is proposed that the original carbonate mineralogy of nummulitid shells may be varied in different environments, and those with metastable mineralogy are excellent for forming hydrocarbon reservoirs. Bivariate plots of Mn versus Sr/Ca and δO values illustrated that Ziyarat limestones were affected by open diagenetic system with high water/rock interaction. Early burial diagenetic temperature calculation based on heaviest oxygen isotope values of micrite and δw of Eocene seawater of −0.85 SMOW showed that temperature was around 39 °C. Cathodluminescence studies of carbonate cements illustrated dull luminescence, because these carbonates were affected mainly by burial diagenesis. This statement is confirmed by δO and δC isotope evidences. Based on different facies and evidences such as absence of reefal facies, calciturbidite deposits, the occurrence of widespread tidal flat deposits and abundant micrites in all microfacies indicate that the Ziyarat Formation was deposited in a homoclinal carbonate ramp environment. In addition, many researchers suggested that due to extreme global warming during the Paleocene-Eocene time, platform margin coral reefs declined in low latitude and heterozoan calcitic foraminifers became abundant and, thus, widespread carbonate ramp systems developed. [ABSTRACT FROM AUTHOR]

The Tale-Zang Formation in Zagros Mountains (south-west Iran) is a Lower to Middle Eocene carbonate sequence. Carbonate sequences of the Tale-Zang Formation consist mainly of large benthic foraminifera (e.g. Nummulites and Alveolina), along with other skeletal and non-skeletal components. Water depth during deposition of the formation was determined based on the variation and types of benthic foraminifera, and other components in different facies. Microfacies analysis led to the recognition of ten microfacies that are related to four facies belts such as tidal flat, lagoon, shoal and open marine. An absence of turbidite deposits, reefal facies, gradual facies changes and widespread tidal flat deposits indicate that the Tale-Zang Formation was deposited in a carbonate ramp environment. Due to the great diversity and abundance of larger benthic foraminifera, this carbonate ramp is referred to as a “foraminifera-dominated carbonate ramp system”. Based on the field observations, microfacies analysis and sequence stratigraphic studies, three third-order sequences in the Langar type section and one third-order sequence in the Kialo section were identified. These depositional sequences have been separated by both type-1 and type-2 sequence boundaries. The transgressive systems tracts of sequences show a gradual upward increase in perforate foraminifera, whereas the highstand systems tracts of sequences contain predominantly imperforate foraminifera. [ABSTRACT FROM AUTHOR]

Well-preserved, isolated specimens of Pseudotaberina were found at three localities in Indonesia, thus enabling the study of the relationships between this genus and Caribbean Archaiasinae. The internal architecture of the chambers of Pseudotaberina consists of four layers of stolon planes, each of which is divided by superposed septula into chamberlets. The chamberlets are connected to the next chambers by foramina opposing the septula. The stolons are Y-shaped. All other Archaiasinae have radial stolon axes combined with an initial involute growth stage, whereas the Soritinae have cross-wise oblique stolon axes, but with evolute growth in the early stages. Pseudotaberina shows a combination of the characters of these two subfamilies, confirming the need to study more Tethyan material to elucidate phylogenetic relationships within this group of large benthic foraminifera. [ABSTRACT FROM AUTHOR]

Knowledge of the assemblage composition of large benthic foraminifera (LBF) in relation to environmental conditions is needed to interpret fossil records. In this study the assemblage composition of LBF is described for a carbonate shelf with a barrier reef system and some reefs outside the barrier. In a total of 140 samples, 34-35 species of LBF were found. Four clusters, roughly corresponding to substrate type were identified. Several small groups of samples were recognized that were collected locally inside, on, or outside the barrier. Microscale environmental gradients within the substrate or in the benthic boundary layer resulted in spatial differentiation of the microhabitat of each species. [ABSTRACT FROM AUTHOR]

Large benthic foraminifers are considered to be good indicators of shallow marine carbonate environments in fossil series. Over the last 50 years, the palaeoenvironment of Tertiary Nummulites accumulations has been a matter of debate, particularly because of difficulties in interpreting these deposits, and in this way, the absence of analogues in present-day seas does not help. The aim of this paper is to insight the different ways Nummulites tests and clasts may accumulate according to their hydrodynamic behaviour. Based on experimental measurements and on SEM observations, it appears that the high primary skeletal porosity of Nummulites made them easily transportable. The calculated threshold shear velocities confirm that large-sized Nummulites can be moved by weak wave-driven currents. This peculiar hydrodynamic behaviour of Nummulites could explain the diversity of depositional models. Depending on local hydrodynamic conditions, autochthonous Nummulites deposits can be preserved as in situ winnowed bioaccumulations or be accumulated offshore, onshore or alongshore, away from the original biotope. [ABSTRACT FROM AUTHOR]

Large benthic foraminifera are significant contributors to sediment formation on coral reefs, yet they are vulnerable to ocean acidification. Here, we assessed the biochemical and morphological impacts of acidification on the calcification of Amphistegina lessonii and Marginopora vertebralis exposed to different pH conditions. We measured growth rates (surface area and buoyant weight) and Ca-ATPase and Mg-ATPase activities and calculated shell density using micro-computer tomography images. In A. lessonii, we detected a significant decrease in buoyant weight, a reduction in the density of inner skeletal chambers, and an increase of Ca-ATPase and Mg-ATPase activities at pH 7.6 when compared with ambient conditions of pH 8.1. By contrast, M. vertebralis showed an inhibition in Mg-ATPase activity under lowered pH, with growth rate and skeletal density remaining constant. While M. vertebralis is considered to be more sensitive than A. lessonii owing to its high-Mg-calcite skeleton, it appears to be less affected by changes in pH, based on the parameters assessed in this study. We suggest difference in biochemical pathways of calcification as the main factor influencing response to changes in pH levels, and that A. lessonii and M. vertebralis have the ability to regulate biochemical functions to cope with short-term increases in acidity. [ABSTRACT FROM AUTHOR]