Scenario Expression Method for Regional Geological Structures

Knowing the GIS expression of geological phenomena is an important basis for the combination of geology and GIS. Regional geological structures include folds, faults, strata, rocks, and other typical geological phenomena and are the focus of geological GIS research. However, existing research on the GIS expression of regional geological structure focuses on the expression of the spatial and attribute characteristics of geological structures, and our knowledge of the expression of the semantic, relationship, and evolution processes of geological structures is not comprehensive. In this paper, a regional geological structure scene expression model with the semantic terms positional accuracy, geometric shape, relationship type, attribute type, and time-type attributes and operations is proposed. A regional geological structure scenario markup language (RGSSML) and a method for mapping it with graphics are designed to store and graphically express regional geological structure information. According to the geological time scale, a temporal reference coordinate system is defined to dynamically express the evolution of regional geological structures. Based on the dynamic division of the time dimension of regional geological structures, the expression method of “time dimension + space structure” for the regional geological structure evolution process is designed based on the temporal model. Finally, the feasibility and effectiveness of the regional geological structure scene expression method proposed in this paper is verified using the Ningzhen Mountain (Nanjing section) as an example. The research results show that the regional geological structure scene expression method designed in this paper has the following characteristics: (1) It can comprehensively express the spatial characteristics, attribute characteristics, semantics, relationships, and evolution processes of regional geological structures; (2) it can be used to realize formalized expression and unified storage of regional geological information; and (3) it can be used to realize dynamic expression of the regional geological structure evolution process. Moreover, it has significant advantages for the expression of regional geological structure semantics, relationships, and evolution processes. This study improves our knowledge of the GIS expression of regional geological structures and is expected to further promote the combination and development of geology and GIS.

Biological Response of Planktic Foraminifera to Decline in Seawater pH

Understanding the way in which a decline in ocean pH can affect calcareous organisms could enhance our ability to predict the impacts of the potential decline in seawater pH on marine ecosystems, and could help to reconstruct the paleoceanographic events over a geological time scale. Planktic foraminifera are among the most important biological proxies for these studies; however, the existing research on planktic foraminifera is almost exclusively based on their geochemical indices, without the inclusion of information on their biological development. Through a series of on-board experiments in the western tropical Pacific (134°33′54″ E, 12°32′47″ N), the present study showed that the symbiont-bearing calcifier Trilobatus sacculifer—a planktic foraminifer—responded rapidly to a decline in seawater pH, including losing symbionts, bleaching, etc. Several indices were established to quantify the relationships between these biological parameters and seawater pH, which could be used to reconstruct the paleoceanographic seawater pH. We further postulated that the loss of symbionts in planktic foraminifera acts as an adaptive response to the stress of low pH. Our results indicate that an ongoing decline in seawater pH may hinder the growth and calcification of planktic foraminifera by altering their biological processes. A reduction in carbonate deposition and predation could have profound effects on the carbon cycle and energy flow in the marine food web.

The Anthropocene

Soon, the Anthropocene will be formally submitted as a chronostratigraphic unit of the Geological Time Scale. This means, in effect, that Homo sapiens will be recognized as a dominant geological force on the planet. But how are anthropologists engaging with this concept in ways that inform larger debates? And what vital concerns or challenges are being raised by anthropologists and scholars in related disciplines as the Anthropocene becomes an increasingly familiar framework for understanding humanity and its place on Earth? One of the underlying motives for the recognition of the Anthropocene is to call attention to humanity’s pervasive impacts on the planet, which are understood as largely damaging for humans and other organisms that live on the Earth. However, the Anthropocene’s root causes still remain hotly disputed. Some see the Anthropocene as a broader extension of humanity’s long-established tendency of landscape modification or niche construction while others assert that the capitalist system is the underlying cause of the Anthropocene’s emergence. Extending from these debates, anthropologists and other social scientists have looked into the ways that the Anthropocene intersects with histories of race and racism, colonialism and neocolonialism, extraction and extinction, and what anthropological methods—from archaeological excavation to multispecies ethnography—can tell us about the differing dimensions of this confounding time. In a more philosophical vein, the Anthropocene has prompted academic researchers to question basic disciplinary distinctions, heuristics, and taken-for-granted assumptions. For anthropologists specifically, it has prompted a re-evaluation of human-centered analytics and inherited notions about what constitutes “the human.” Without a doubt, this literature and the scholarly debates that animate it will only grow and evolve with time, but here a focus is placed on the origins and politics of the Anthropocene, with specific focus on its relationship to historical and contemporary inequalities. This bibliography also considers what the Anthropocene means for socio-cultural theory, anthropological methods, and movements toward decolonization and collective liberation in a deeply compromised world.

Large Scale Volcanism: an explanation for the heat-death of Venus like worlds

<p class="p1"><span class="s1">Large scale volcanism has played a critical role in the long-term habitability </span><span class="s1">of Earth and possibly Venus.<span class="Apple-converted-space">  </span>We examine the timing of Large Igneous Provinces </span><span class="s1">(LIPs) through Earth’s history [1] to estimate the likelihood of nearly simultaneous </span><span class="s1">events that could drive a planet into an extreme moist or runaway greenhouse, </span><span class="s1">quenching subductive plate tectonics. Such events would end volatile cycling </span>and may have caused the heat-death of Venus. Using the Earth's LIP record <span class="s1">a conservative estimate of the rate of LIPs in a random history statistically </span>the same as Earth’s, pairs and triplets of LIPs closer in time <span class="s1">than 0.1-1 Myrs are likely. This simultaneity threshold is significant to the </span><span class="s1">extent that it is less than the time over which environmental effects </span><span class="s1">have been shown to persist, for example in the Siberian Traps record [2,3].</span></p> <p class="p1"><span class="s1">[1] Ernst, R.E. et al. (2021). Large Igneous Province Record Through Time and </span><span class="s1">Implications for Secular Environmental Changes and Geological Time-Scale </span>Boundaries. In: Ernst, R.E., Dickson, A.J., Bekker, A. (eds.) Large Igneous <span class="s1">Provinces: A Driver of Global Environmental and Biotic Changes. AGU Geophysical </span><span class="s1">Monograph 255 (pp. 3-26).</span></p> <p class="p1"><span class="s1">[2] Burgess, S.D. et al. (2014). High-precision timeline for Earth’s most </span><span class="s1">severe extinction. Proceedings of the National Academy of Sciences, 111:</span></p> <p class="p1"><span class="s1">3316–3321 [correction 2014, 111: 5050]. </span></p> <p class="p1"><span class="s1">[3] Burgess, S.D. & Bowring, S.A. (2015). High-precision geochronology confirms </span><span class="s1">voluminous magmatism before, during and after Earth's most severe extinction. </span><span class="s1">Sci. Adv. 1 (7), e1500470. http://dx.doi.org/10.1126/sciadv.1500470. </span></p>

A template for an improved rock-based subdivision of the pre-Cryogenian time scale

The geological time scale before 720 Ma uses rounded absolute ages rather than specific events recorded in rocks to subdivide time. This has led increasingly to mismatches between subdivisions and the features for which they were named. Here we review the formal processes that led to the current time scale, outline rock-based concepts that could be used to subdivide pre-Cryogenian time and propose revisions. An appraisal of the Precambrian rock record confirms that purely chronostratigraphic subdivision would require only modest deviation from current chronometric boundaries, removal of which could be expedited by establishing event-based concepts and provisional, approximate ages for eon-, era- and period-level subdivisions. Our review leads to the following conclusions: 1) the current informal four-fold Archean subdivision should be simplified to a tripartite scheme, pending more detailed analysis, and 2) an improved rock-based Proterozoic Eon might comprise a Paleoproterozoic Era with three periods (early Paleoproterozoic or Skourian, Rhyacian, Orosirian), Mesoproterozoic Era with four periods (Statherian, Calymmian, Ectasian, Stenian) and a Neoproterozoic Era with four periods (pre-Tonian or Kleisian, Tonian, Cryogenian and Ediacaran). These proposals stem from a wide community and could be used to guide future development of the pre-Cryogenian timescale by international bodies.

Rheological stratification in impure rocksalt during long-term creep: morphology, microstructure and numerical models of multilayer folds in the Ocnele Mari salt mine, Romania

Analysis and prediction of deformations in salt tectonics and salt engineering require information about the mechanical properties of rocksalt at time scales far longer than possible in the laboratory. It is known that at laboratory time scales, rocksalt samples with different composition and microstructure show a variance in steady-state creep rates, but it is not known how this variance is manifested at low strain rates and corresponding deviatoric stresses. Here, we aim to quantify this from the analysis of multilayer folds that developed over geological time scale. We studied excellent exposures of layered, folded rocksalt in the Ocnele Mari salt mine in Romania. The formation is composed of over 90 % of halite, while distinct multiscale layering is caused by variation in the fraction of impurities. Regional tectonics and mine-scale fold structure are consistent with deformation in a shear zone, after strong shearing in a regional detachment, forming over ten meter-scale chevron folds of a tectonically sheared sedimentary layering, with smaller folds developing on different scales in the hinges. Morphology of the fold pattern at various scales clearly indicates that during folding the sequence was mechanically stratified. The dark layers contain more impurities and are characterized with a more regular layer thickness as compared to the bright layers and, thus, are inferred to have higher viscosities. Optical microscopy of Gamma-decorated samples shows a strong shape preferred orientation of halite grains parallel to the foliation, which is reoriented parallel to the axial plane of the folds studied. Microstructures indicate dislocation creep, together with extensive fluid-assisted recrystallization and strong evidence for solution-precipitation creep indicative for linear (Newtonian) viscous rheology during folding. Deviatoric stress during folding was lower than during shearing in the detachment, around 1 MPa. We investigate fold development on various scales in a representative multilayer package using finite element numerical models, constrain the relative layer thicknesses in a selected outcrop and design a numerical model. We explore the effect of different Newtonian viscosity ratios between the layers on the evolving folds on different scales. Through the comparison of the field data and numerical results, we estimate that the effective viscosity ratio between the layers was larger than 10 and up to 20. Additionally, we demonstrate that the considerable variation of the layer thicknesses is not a crucial factor to develop folds on different scales. Instead, unequal distribution of the thin layers, which organize themselves into effectively single layers with variable thickness can trigger deformation at various scales. Our results show that impurities can significantly change the viscosity of rocksalt deforming at low deviatoric stress and introduce anisotropic viscosity, even in relatively pure, layered rock.

The record of the Eocene-Oligocene Transition and the “Grande Coupure”. Magnetostratigraphic constraints from the Ebro Basin revisited.

<p>Magnetostratigraphy is the key to put disparate chronological pieces together in a consistent chronostratigraphic framework. Provided that a long continuous record of reversals can be obtained from the sedimentary record, a correlation with the GPTS may be established. Magnetostratigraphy provides added value to the chronology as long as it keeps certain independence from external age constraints, such as bioevents calibrated elsewhere or radiochronologic data.</p><p>An independent correlation is meant to not be anchored to a given chron on the basis of an external age constrain. Our experience recommends that external age constraints are best taken with flexibility, allowing for the searching of a best fit between the magnetic polarity sequence (in meters) and the GPTS (in million-years). This rationale relies on the fact that the Geological Time Scale is the tool that allows earth-scientist of many varied disciplines to understand and discuss about the dimension of time. But the time scale calibration is a task in continuous refinement. As the accuracy and precision of the dating tools increases, our ability to unravel lag times in geological processes increases too. As more refined data is produced, the calibration of the time scale reveals as an ongoing task rather than a final product.</p><p>Here we present the case of the Eocene-Oligocene Transition (EOT) as recorded in alluvial-lacustrine sediments of the eastern Ebro Basin. An earlier work provided a magnetostratigraphic correlation that was in agreement with small-mammals biostratigraphic data. A key constraint to this study was the Santpedor locality, which yielded a characteristic post-Grand Coupure small mammal assemblage, then attributed to the lowest Oligocene.</p><p>An extended record of the magnetostratigraphy has challenged the earlier correlation and puts forward an alternate scenario that reveals a misfit with earlier and recent biochronological interpretations of the fossil mammal record. The significance of this discrepancy in terms of heterochrony of biostratigraphic events, the punctuated character of faunal replacement across the EOT, and time lags between the marine and continental realms may need to be addressed.</p>