ONSHORE-OFFSHORE TRENDS IN THE TEMPORAL RESOLUTION OF MOLLUSCAN DEATH ASSEMBLAGES: HOW AGE-FREQUENCY DISTRIBUTIONS REVEAL QUATERNARY SEA-LEVEL HISTORY

Palaios, Journal Year: 2023, Volume and Issue: 38(3), P. 148 - 157

Published: March 31, 2023

Abstract Surficial shell accumulations from shallow marine settings are typically averaged over centennial-to-millennial time scales and dominated by specimens that died in the most recent centuries, resulting strongly right-skewed age-frequency distributions (AFDs). However, AFDs modern offshore (outer shelf uppermost continental slope) still need to be explored. Using individually dated shells (14C-calibrated amino acid racemization), we compared along an onshore-offshore gradient across southern Brazilian shelf, with sites ranging inner shallow-water (< 40 m) offshore, deep-water (> 100 settings. The duration of averaging is slightly higher deeper water environments, AFD shapes change depositional profile. due dominance millennia (median age range: 0–3 ka). In contrast, on outer slope, symmetrical left-skewed following Last Glacial Maximum 15–18 changes observed properties AFDs—increased median decreased skewness, but only increased temporal mixing—likely reflect sea level concurrent depth-related biological productivity. These results suggest a passive margin subject post-glacial sea-level changes, magnitude time-averaging assemblages less variable profile than assemblage ages AFDs.

Language: Английский

---

The origins and transformation of carbonate mud during early marine burial diagenesis and the fate of aragonite: A stratigraphic sedimentological perspective

Earth-Science Reviews, Journal Year: 2023, Volume and Issue: 239, P. 104366 - 104366

Published: Feb. 26, 2023

The current understanding of the origins modern carbonate muds and their early stages transformations are reviewed. fine-grained nature such sediments makes them susceptible to intensive structural chemical alteration at relatively shallow burial depths driven especially by mineral instability under microbially mediated reactions within sediment associated with decay organic matter. Whereas transformation high Mg calcite (HMC) low magnesian (LMC) generally takes place incongruently in situ, that aragonite is predominantly via congruent dissolution. loss produces a huge potential flux which translocated sediment. Parallel studies on Quaternary sediments, investigations stratigraphic record have shown low-energy settings component leads formation diagenetic bedding (such as limestone-marl-alternations or LMAs), related bipartite lithologies, some types hardgrounds, secondary mudrocks, significant modification original skeletal biota. There uncertainties exact sources for precursor aragonite, where released carbonates reprecipitate column, how much (and hence carbon) back-fluxed water this affects palaeoenvironmental proxies, environmental distributions these processes. evidence from record, matter was able accumulate promoting transformations, changes carbonate-rich took very early, (decametre less) depths, affecting what we now see micron outcrop scale. complexity inter-relationships fundamental processes has received more attention recent years, though implications still seem remarkably undervalued.

Language: Английский

---

Temporal scales, sampling designs and age distributions in marine conservation palaeobiology

Geological Society London Special Publications, Journal Year: 2023, Volume and Issue: 529(1), P. 1 - 39

Published: March 29, 2023

Abstract Conservation palaeobiology informs conservation and restoration of ecosystems by using the fossil record to discriminate between baseline novel states assess ecosystem response perturbations. Variability in time-scale palaeobiological data can generate patterns that either exaggerate or mute magnitude biotic changes. We identify two approaches remedy challenges associated with mixing post-impact transformation stratigraphic depth time. First, combining surface death assemblages both (1) preserved subsurface historical layers (2) living better resolve nature shifts than within-core surveys live–dead analyses alone. Second, post-mortem age distributions skeletal particles their preservation are not only informative about resolution time averaging but also timing changes abundance producers. High youngest cohorts is a null expectation disintegration burial dynamic. When this dynamic accounted for, benthic invertebrates from Holocene sediments often reveal high volatility, prolonged turn-offs production pervasive regime obscured raw record.

Language: Английский

---

High-resolution seismic record of the Quaternary palaeoenvironments along a Dalmatian-type coast (Lošinj Channel, Adriatic Sea)

Marine Geology, Journal Year: 2024, Volume and Issue: 474, P. 107325 - 107325

Published: May 25, 2024

Language: Английский

---

Microfacies analysis of the Palaeocene Lockhart limestone on the eastern margin of the Upper Indus Basin (Pakistan): Implications for the depositional environment and reservoir characteristics

The Depositional Record, Journal Year: 2023, Volume and Issue: 9(1), P. 152 - 173

Published: Jan. 20, 2023

Abstract A detailed sedimentological analysis of the Palaeocene Lockhart Limestone has been conducted to evaluate depositional environment, diagenetic processes and hydrocarbon potential eastern margin Upper Indus Basin. From bottom top, there are three microfacies recorded. The lower microfacies, composed fine‐grained micrite some dolomite, reflect low energy calm palaeo‐current in shallower section (1–2 m) inner shelf close shore. middle contain algae that suggest 5–15 m water depth, especially along inner‐middle shelf, but fractured mixed bioclasts material indicate moderately active wave base. Progressing from a gradual shift orthochem allochem components is observed. top dominated by massive benthic microfossils, indicating moderate energy‐water conditions with normal salinity. However, presence limestone intraclasts surrounded microspar, miliolids nummulites at indicates high‐energy environment increasing salinity depths 20 130 m. These findings show was deposited shallow spanning inner‐mid shelf. Diagenetic observed include micritisation, cementation, dissolution, replacement, physical chemical compaction, fracture filling calcite cement. represents deepening upward sequence below system tract highstand systems regressive could good reservoir characteristics, serve as an excellent rock, be primary target for future exploration.

Language: Английский

---

Ideas and perspectives: Human impacts alter the marine fossil record

Biogeosciences, Journal Year: 2024, Volume and Issue: 21(9), P. 2177 - 2188

Published: May 3, 2024

Abstract. The youngest fossil record is a crucial source of data documenting the recent history marine ecosystems and their long-term alteration by humans. However, human activities that reshape communities habitats also alter sedimentary biological processes control formation archives recording those impacts. These diverse physical, geochemical, disturbances include changes in sediment fluxes due to alluvial coastal landscapes, seabed disturbance bottom trawling ship traffic, ocean acidification deoxygenation, removal native species, introduction invasive ecosystem engineers. novel modify sedimentation rates, depth intensity mixing, pore-water saturation state, preservation potential skeletal remains – parameters controlling completeness spatiotemporal resolution record. We argue humans have become major force transforming nature ways can both impede improve our ability reconstruct past ecological climate dynamics. A better understanding feedback between impacts on offers new research opportunities tools for interpreting geohistorical ongoing anthropogenic transformation ocean.

Language: Английский

---

Exploring the past to protect the future: an analysis of conservation paleobiology in South America

Anais da Academia Brasileira de Ciências, Journal Year: 2025, Volume and Issue: 97(2)

Published: Jan. 1, 2025

Abstract Conservation paleobiology, an expanding field, employs taphonomy tools to investigate past environmental conditions and organisms before human impacts, thereby addressing key conservation issues. This review examines the concepts, approaches events in emphasizing aquatic coastal often-overlooked contributions from Brazil South America. America, with its vulnerable biodiversity, unique geology rich fossil diversity, is a natural laboratory for understanding ecosystems—a considerable potential as center leading paleobiology research. However, America underrepresented, contributing only 5% of total publications (67% it Brazil). Most American authors are geoscientists publishing mainly on mollusks, also they produced fewer studies than those more developed countries. Noteworthy, Brazilian National Council Scientific Technological Development ranks third globally funding articles. Clearly, still predominantly practiced nations geoscience fields. Other challenges include underutilization geohistorical data gap between theory practice. To address these issues, future should integrate conservationist perspectives align them societal needs. Hence, anticipated growth could bolster promote sustainability generations.

Language: Английский

---

Identification of the mode of evolution in incomplete carbonate successions

BMC Ecology and Evolution, Journal Year: 2024, Volume and Issue: 24(1)

Published: Aug. 23, 2024

Abstract Background The fossil record provides the unique opportunity to observe evolution over millions of years, but is known be incomplete. While incompleteness varies spatially and hard estimate for empirical sections, computer simulations geological processes can used examine effects in silico . We combine different modes (stasis, (un)biased random walks) with deposition carbonate platforms strata how well mode recovered from time series, test results vary between positions platform multiple stratigraphic architectures generated by sea level curves. Results Stratigraphic architecture position along an onshore-offshore gradient has only a small influence on statistical tests. For walks, support correct decreases series length. Visual examination trait lineages shows that rather than incompleteness, maximum hiatus duration determines much differ original evolutionary process. Gradual directional more susceptible effects, turning it into punctuated evolution. In contrast, stasis remains unaffected. Conclusions • Fossil favor recognition both complex, Not presence rare, prolonged gaps largest effect This suggests incomplete sections regular frequency durations potentially preserve history without major biases. Understanding external controls such as fluctuations crucial distinguishing genuine

Language: Английский

---

The Paradox of Predictability Provides a Bridge Between Micro- and Macroevolution

Journal of Evolutionary Biology, Journal Year: 2024, Volume and Issue: 37(12), P. 1413 - 1432

Published: Aug. 29, 2024

Abstract The relationship between the evolutionary dynamics observed in contemporary populations (microevolution) and evolution on timescales of millions years (macroevolution) has been a topic considerable debate. Historically, this debate centers inconsistencies microevolutionary processes macroevolutionary patterns. Here, we characterize striking exception: emerging evidence indicates that standing variation rates phenotypic divergence is often positively correlated. This apparent consistency micro- macroevolution paradoxical because it contradicts our previous understanding so far unexplained. explore prospects for bridging through an examination “paradox predictability.” We begin by explaining why divergence–variance correlation paradox, followed data analysis to show general phenomenon across broad range temporal scales, from few generations tens years. Then review complementary approaches quantitative genetics, comparative morphology, evo-devo, paleontology argue they can help address paradox shared vantage point recent work evolvability. In conclusion, recommend methodological orientation combines different kinds short-term long-term using multiple analytical frameworks interdisciplinary research program. Such program will increase how works within timescales.

Language: Английский

---

Impact of diagenesis and pore aspects on the petrophysical and elastic properties of carbonate rocks from southern Lebanon

Bulletin of Engineering Geology and the Environment, Journal Year: 2023, Volume and Issue: 82(3)

Published: Feb. 10, 2023

Language: Английский

---