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On July 18, 2023, on the K54 + 670 ~ K54 + 700 section of G351 National Highway in Baoxing County, Ya'an City, Sichuan Province, the rock mass (30° 25′ 4.8″ N, 102° 50′ 21.84″ E) located at the entrance of Leying in the Guanyinyan Open-cut Tunnel and affected by Lushan earthquakes and heavy rainfall factors suffered a rock mass collapse accident (hereinafter referred to as the Guanyinyan collapse, or collapse). It is a typical delayed rock mass collapse event that occurs under the influences of historical earthquake sequences and rainy season rainfall. The collapsed area has the maximum thickness close to 2 m, and a volume of about 1500–2000 m3. Some collapsed rocks have rolled into the interior of the tunnel and the riverbed, and boulders with a diameter of nearly 5 m have been found in the river channel. Most of the collapsed material accumulates on the road, approximately 1260 m3, burying some 30 m of the highway, severely affecting the normal use thereof. This article used a detailed field investigation, unmanned aerial vehicle (UAV) photogrammetry, historical image comparison, and numerical simulation methods to gain a deeper understanding of the engineering geology and historical earthquake situation in the study area. A three-dimensional site model was also established to identify the rock mass structural joints and accumulation conditions in the collapsed area, and the deterioration and fracture factors and historical evolution process of the dangerous rock mass were briefly analyzed, Finally, a comparative analysis was conducted between the simulated results using the three-dimensional finite discrete element method (FDEM) and the dynamic process as evinced by of real-time video footage. The collapse mainly experienced a local instability stage, stress adjustment stage, and overall collapse-accumulation stage. The further understanding of its motion characteristics and energy evolution can provide a basis for subsequent protection design and also a valuable experience for similar research in the region. [ABSTRACT FROM AUTHOR]

Chess engines are suites of algorithms that evaluate game positions through prediction—they calculate billions of possible moves, dozens of steps into the future state of play. And over the past two decades, these algorithms have usurped humans as the principal arbiters of chess knowledge. Openings, tactics, and strategies are now all authenticated, and often dictated, by engine analysis, leading to new styles of play. This article uses the example of predictive chess engines to conceptualize an emergent temporal interplay between the future and the present. Drawing inspiration from historical metaphors of geology, this article proposes a topographical approach to temporal becoming. In this approach, engine predictions facilitate not preparations for some forecasted future state, but future‐reliant calibrations of present activity, where second‐by‐second algorithmic futures are used to make second‐by‐second decisions. [ABSTRACT FROM AUTHOR]

Simple Summary: The riverine ecosystem of the Aurès Mountains in Algeria is situated in the southern part of the Mediterranean basin. This unique region is an important centre of speciation, with a distinct number of regional endemics—some of which are still undescribed or very poorly studied. Given the importance of biomonitoring the ecological status of surface waters in this region, as well as the need to study and protect the diversity of aquatic fauna, information on the taxonomic composition and status of regional species is essential. Our attention was focused on the mayflies of the genus Baetis Leach, 1815 (Ephemeroptera: Baetidae), a typical element of the river macrozoobenthos within the Aurès Mountains. A new species of Baetis (Baetis) dihyae sp. nov. is described for larvae and attributed to the Baetis alpinus species group using morphological and molecular evidence. The affinities of Baetis (Baetis) dihyae sp. nov. to the closely related Palearctic species Baetis (B.) alpinus (Pictet, 1843); the western Alps endemic Baetis (B.) nubecularis Eaton, 1898; and B. (B.) pasquetorum Righetti & Thomas, 2002 (reported only from a few localities in southern France) are discussed in detail. The record and further description of a new species is the first contribution to the knowledge of the relatively diverse mayfly family Baetidae, distributed in the Aurès Mountains. Establishing a representative level of diversity of the macroinvertebrate fauna of the region is closely linked to both field studies and analyses of the main pathways of invasion of its individual elements. Using an extensive data set on the geology and historical biogeography of different faunal groups as well as analysing the diversity of the Baetis alpinus species-group representatives in Western Europe and the Maghreb, we examined in this contribution its colonisation pathways in North Africa. A new species, Baetis (Baetis) dihyaesp. nov., belonging to the Baetis alpinus species group, is described and illustrated based on larval material collected in the Aurès Mountains (northeastern Algeria) in 2020–2021. This new species is closely related to three European species, e.g., Baetis (B.) alpinus (Pictet, 1843); B. (B.) nubecularis Eaton, 1898; and B. (B.) pasquetorum Righetti & Thomas, 2002 by the combination of the following characteristics: (i) more than one short, stout bristle at the tip of segment II of the maxillary palp and (ii) a well-developed paracercus. However, the new species clearly differs from all congeners of the Baetis alpinus species group primarily by the (a) structure of mouthparts—with 14–18 long submarginal setae arranged in a single irregular row on the dorsal surface of the labrum; 2–6 short, stout bristles at the tip of segment II of the maxillary palp; and segment II of the labial palp without a considerably developed apico-internal lobe); (b) setation of abdominal terga, with a few triangular-shaped scales sparsely scattered near the posterior margin only; and (c) a well-developed paracercus, comprised of more than 50 segments. Primary data on the biology and distribution of this new species are provided, and molecular affinities are verified by the analysis of COI (barcode) sequences. Detailed notes on the distribution of mayfly species belonging to the Baetis alpinus species group common in Western Europe and the western part of North Africa are presented. The historical movement of Baetis representatives between Europe, North West Africa, and subsequently Algeria, with the land bridges 'Strait of Gibraltar' and 'Strait of Sicily' as colonization routes, is discussed in detail and identified in the present study as the Western Algeria colonization path and Eastern Algeria colonization path, respectively. [ABSTRACT FROM AUTHOR]

1. Introduction Aida Sergeevna Andreeva-Grigorovich, an eminent Soviet and Ukrainian palynologist and micropalaeontologist, passed away on the 13 SP th sp of April 2022 at the age of 86. Later, an updated Palaeogene dinoflagellate cyst zonation was proposed by Aida Sergeevna and her colleagues for the southern regions of the former USSR (Andreeva-Grigorovich [6]) and Ukraine (Andrejeva-Grigorovich and Shevchenko [26]; Andreeva-Grigorovich et al. [23]). For example, she established a new genus ( I Carpatella i ), and described 18 new species (Grigorovich [33], [34]; Andreeva-Grigorovich and Savitskaya [18], [19]; Andreeva-Grigorovich et al. [23]). Aida Sergeevna paid special attention to the study of boundary strata such as the Eocene/Oligocene transition (Andreeva-Grigorovich and Portnyagina [17]; Andreeva-Grigorovich [5]; Andreeva-Grigorovich et al. [22], [13]) and the Palaeogene/Neogene boundary (Grigorovich [36]; Andreeva-Grigorovich and Gruzman [10], [11]; Andreeva-Grigorovich [7]). [Extracted from the article]

Fault traces and offsets, cross-section length changes, paleomagnetic inclination and declination anomalies, and stress-direction indicators with ages back to 90 Ma are collected from the geologic literature on the western United States and northern Mexico. Finite-element program Restore simulates paleokinematics by weighted least squares and integrates displacements, strains, and rotations back in time, producing paleogeologic maps, as well as maps of velocity, heave rate, strain rate, and stress direction at 6 m.y. intervals. After calibrating three program parameters against neotectonic velocities from geodesy, all classes of data except inclination anomalies are fit reasonably well. The kink in the San Andreas fault near San Gorgonio Pass has been gradually restored by slip on adjacent faults and automated smoothing. Piercing- point pairs successfully restored along the San Andreas--Gulf of California plate boundary include the Pelona and Orocopia Schists at 6 Ma, the Pinnacles and Neenach Volcanics at 21 Ma, and the Jolla Vieja and Poway conglomerates adjacent to their Sonoran source at 48-42 Ma. During 18-6 Ma, rapid extension on the Oceanside detachment fault system was restored, placing present San Nicolas Island adjacent to present Rosarito, Baja California, at 18 Ma. Since ca. 18 Ma, the western Transverse Ranges have rotated 70° clockwise, restoration of which implies that sinistral faults in this province originated with NNE trends. The first contact between the Pacific and North America plates at ca. 28 Ma was not associated with any dramatic increase in dextral faulting on land; instead, the primary result was extension in the Plush Ranch--Vasquez-Diligencia basins and Colorado River corridor, probably driven by an unstable triple- junction and accelerated by heating and uplift of North America above enlarging slab windows. [ABSTRACT FROM AUTHOR]

The use of geological interpretations to better understand features that are observed outside the Earth defines what is known as planetary geology. It is a highly multi‐disciplinary field, using concepts from many areas of human knowledge to better understand the many objects of the Universe. Interpretations tend to be based on analogue models, created from observations made on the Earth and extrapolated to the many geological contexts of other celestial bodies. It is assumed that these models can always be used, as long as corrections considering differences in properties such as temperature, mass, atmospheric, crustal and mantel composition, amongst others, are made. In most cases, such correlations are possible, requiring minor to no significant modifications. However, a reasonable number of extra‐terrestrial features cannot be explained using the Earth as the unique comparison ground, requiring the use of other analogues as a basis, or even the creation of models and theories from scratch. Here, we present an overview of planetary geology: what it is, the limits of its application, the current state of the art and the meaning of this line of research in the era in which we live, where the exploration of other objects of the Solar System is a reality. [ABSTRACT FROM AUTHOR]

Since the major flood event in 2007, RPS has been deeply involved in investigating, understanding and reducing flood risk across the Hull and Haltemprice catchment. RPS has developed and refined a complex integrated catchment model by combining Yorkshire Water's model of below-ground assets with data for the watercourses and overland flow paths obtained from the Environment Agency, East Riding of Yorkshire Council and Hull City Council. RPS used the model to identify major schemes, leading to the design of flood alleviation schemes at Willerby and Derringham, Anlaby and East Ella, and Cottingham and Orchard Park. With further enhancements, the model has been used to better understanding of the complex interactions between the various water systems and solutions are being identified for a long-term plan. Hull has many unique features, driven by its topography, geology and the historical developments of its sewerage network and waterways. These specific challenges require bespoke solutions and there is a clear desire among the partner organisations to work together to drive contemporary blue–green solutions. This requires multi-agency working and progressive thinking to deliver effective flood risk management. This paper reviews the challenges in understanding and resolving these issues. [ABSTRACT FROM AUTHOR]

A large part of the hydrated oceanic lithosphere consists of serpentinites exposed in ophiolites. Serpentinites constitute reactive chemical and thermal systems and potentially represent an effective sink for CO2. Understanding carbonation mechanisms within ophiolites are almost exclusively based on studies of outcrops, which can limit the interpretation of fossil hydrothermal systems. We present stable and radiogenic carbon isotope data that provide insights into the isotopic trends and fluid evolution of peridotite carbonation in ICDP Oman Drilling Project drill holes BA1B (400‐m deep) and BA3A (300‐m deep). Geochemical investigations of the carbonates in serpentinites indicate formation in the last 50 kyr, implying a distinctly different phase of alteration than the initial oceanic hydration and serpentinization of the Samail Ophiolite. The oldest carbonates (∼31 to >50 kyr) are localized calcite, dolomite, and aragonite veins, formed between 26°C and 43°C and related to focused fluid flow. Subsequent pervasive small amounts of dispersed carbonate precipitated in the last 1,000 years. Macroscopic brecciation and veining of the peridotite indicate that carbonation is influenced by tectonic features allowing infiltration of fluids over extended periods and at different structural levels such as along fracture planes and micro‐fractures and grain boundaries, causing large‐scale hydration of the ophiolite. The formation of dispersed carbonate is related to percolating fluids with δ18O lower than modern ground and meteoric water. Our study shows that radiocarbon investigations are an essential tool to interpret the carbonation history and that stable oxygen and carbon isotopes alone can result in ambiguous interpretations. Plain Language Summary: Water‐rock interactions that have biological and economic importance have received increasing interest in recent years. Carbon species, stored in the atmosphere, biosphere, oceans, and lithosphere, are profoundly affected by biotically and abiotically controlled exchange reactions among these reservoirs. Carbon is an essential element for life and contributes to the greenhouse effect in the form of CO2 and CH4. Unraveling water‐rock reactions that transform atmospheric CO2 into thermodynamically stable carbonates helps to better understand long‐term carbon storage in the lithosphere and its long‐term influence on climate and to better evaluate the potential for life within the lithosphere. This study uses samples recovered by drilling mantle sequences of the Wadi Tayin Massif in Oman and presents chemical data to evaluate carbon sources, speciation, and transformations. The Wadi Tayin Massif is located in the Samail Ophiolite and comprises mantle rocks. Mantle rocks react in contact with water to form serpentine and create an environment that promotes the transformation of CO2 into carbonates. Our results demonstrate large‐scale carbonization of the massif and a dominance of dispersed carbonate formation below the surface. Our study provides insights into the carbon cycle and will help to evaluate the potential of mantle rocks to store carbon and sustain life. Key Points: Two carbonate occurrences are observed: localized dolomite, calcite, and aragonite veins and pervasive dispersed carbonatesCarbonate precipitation in the peridotite occurred in the last 50 kyr at moderate temperatures, post‐dating ocean‐floor serpentinizationThe oxygen isotope composition of dispersed carbonates indicates precipitation from highly 18O‐depleted fossil groundwater [ABSTRACT FROM AUTHOR]

Inquiry-based learning is an educational strategy that emphasizes the student's role in the learning process by having them propose and test hypotheses through experimentation and/or the collection of observational data. It emphasizes active participation, allowing students to take ownership of their learning. In doing so, inquiry-based learning results in the building of the critical thinking and communication skills necessary for participation in all fields of study. In this study, we provide an example of how to adapt an inquiry-based activity used in upper-level paleontology courses so that it can be used in all paleontology-related courses, as well as in lower-level historical geology courses. In paleoecology, large surfaces of substrate with encrusting organisms provide a wealth of paleoecologic information about the ancient communities and are an excellent tool for inquiry-based learning. However, a challenge in paleoecology is that large slabs of rock containing fossil communities are not easy to obtain. In this exercise, students create a simulated substrate using paper and stickers. Feedback showed that students were engaged in the process of doing science and used the skills that they had learned throughout the semester. They gained self-confidence and realized that they can, in fact, do science. [ABSTRACT FROM AUTHOR]

The complex urban geology of the historic center of Naples is characterized by the emplacement of products from two adjoining volcanic areas that were reworked by alluvial and coastal processes. To expand the geologic knowledge of this densely populated area, multidisciplinary research was carried out on the recently drilled San Marcellino borehole, as part of a larger borehole collection project. Critical revision of 290 previously drilled sequences, and a complete set of tephrostratigraphic, sedimentologic, and paleoecologic data obtained on the San Marcellino stratigraphy, informed a hydrogeological conceptual model of water circulation and paleoenvironmental reconstruction of the city historic center. Both before and after the Neapolitan Yellow Tuff eruption, ca. 15 ka, the landscape was characterized by a marine to transitional paleoenvironment. This signifies a good balance between sea-level rise and volcaniclastic inputs, consisting of both primary and remobilized deposits in an area that is also subject to bradyseismic oscillations. Amongst the primary pyroclastic deposits, the products of an explosive event from Campi Flegrei about 16 ka, with an eastward-directed sustained-column phase, were recognized. Collectively, the multidisciplinary data obtained in this study favor the presence of a double-aquifer conceptual model, characterized by a volcanic and a marine-sedimentary aquifer. [ABSTRACT FROM AUTHOR]

Dehydration and hypersalinity challenge non-marine organisms crossing the ocean. The rate of water loss and saltwater tolerance thus determine the ability to disperse over sea and further influence species distribution. Surprisingly, this association between physiology and ecology is rarely investigated in terrestrial vertebrates. Here we conducted immersion experiments to individuals and eggs of six lizard species differently distributed across Taiwan and the adjacent islands to understand if the physiological responses reflect the geographical distribution. We found that Plestiodon elegans had the highest rate of water loss and the lowest saltwater tolerance, whereas Eutropis longicaudata and E. multifasciata showed the lowest rate of water loss and the highest saltwater tolerance. Diploderma swinhonis, Hemidactylus frenatus, and Anolis sagrei had medium measurements. For the eggs, only the rigid-shelled eggs of H. frenatus were incubated successfully after treatments. While, the parchment-shelled eggs of E. longicaudata and D. swinhonis lost or gained water dramatically in the immersions without any successful incubation. Combined with the historical geology of the islands and the origin areas of each species, the inferences of the results largely explain the current distribution of these lizards across Taiwan and the adjacent islands, pioneerly showing the association between physiological capability and species distribution. [ABSTRACT FROM AUTHOR]

The Paleozoic evolution of Patagonia was the focus of controversies between its allochthonous or autochthonous origin. The arrival of plate tectonics supported new allochthonous alternatives and from an initial fixist resistance, different mobilistic hypotheses have made their way. There is currently some consensus about its allochthony, but there is no agreement on collision times or in the configuration of the continental blocks involved. Based on the present data an alternative is developed that fits better with existing information. The northeast-vergent deformation in Ventania System, the Hespérides Basin, its wide longitudinal and transverse distribution, show that collision occurred in the northern sector of Northern Patagonian Massif, and extended through the southern African Gondwanides. Their similar metamorphic and tectonic patterns identified a previous southward subduction with a Permian climax, characteristic of a continent-continent collision. The associated magmatic arc has been partially obliterated by slab-breakoff and delamination in the Late Permian-Triassic. The western magmatic belt along the Pacific margin is older, spanning from Devonian to mid-Carboniferous. The Chaitenia island arc collision in Upper Devonian produced an episode of exhumation and uplift. This western belt extends into Tierra del Fuego island and its contour allows tentatively to recognize a Southern Patagonian terrane. It is speculated that this block may have included the Antarctic Peninsula, although more data is needed to characterize its composition and areal development. However, it is concluded that the dimensions of this southern terrane cannot justify the broad regional deformation of the Gondwanides. [ABSTRACT FROM AUTHOR]

In this unit students evaluate evidence quality, learn central organizing principles of geology, and develop a more sophisticated understanding of the nature of science in the context of a model-based inquiry unit. In this unit students learn about three models describing how the Earth's surface might experience large-scale changes over long periods of time: The shrinking Earth model Continental drift Plate tectonics These three geologic models have been accepted by different factions of the scientific community at different times (Oreskes 1988). This is just a sample of the many geologists and earth scientists whose work has contributed to science; teachers are encouraged to adapt this as they see fit and have students explore the lives of other scientists as well. Concluding thoughts: deepening students' understanding of the nature of science The goals of this unit are to help students learn central organizing principles of geology, and also to develop a more sophisticated sense of the nature of science. [Extracted from the article]

This review aims to synthesize the current knowledge of sediment dynamics using insights from long‐term research conducted in the watershed draining to the Chesapeake Bay, the largest estuary in the U.S., to inform management actions to restore the estuary and its watershed. The sediment dynamics of the Chesapeake are typical of many impaired watersheds and estuaries around the world, and this synthesis is intended to be relevant and transferable to other sediment‐impaired systems. The watershed's sediment sources, transport, delivery, and impacts are discussed with implications for effectively implementing best management practices (BMPs) to mitigate sediment issues. This synthesis revealed three key issues to consider when planning actions to reduce sediment loading: Scale, time, and land use. Geology and historical land use generated a template that current land use and climate, in addition to management, are acting upon to control sediment delivery. Important sediment sources in the Chesapeake include the Piedmont physiographic region, urban, and agricultural land use, and streambank erosion of headwater streams, whereas floodplain trapping is important along larger streams and rivers. Implementation of BMPs is widespread and is predicted to lead to decreased sediment loading; however, reworking of legacy sediment stored in stream valleys, with potentially long residence times in storage, can delay and complicate detection of the effects of BMPs on sediment loads. In conclusion, the improved understanding of sediment sources, storage areas, and transport lag times reviewed here can help target choices of BMP types and locations to better manage sediment problems—for both local streams and receiving waters. This article is categorized under:Science of Water > Water QualityWater and Life > Stresses and Pressures on EcosystemsWater and Life > Conservation, Management, and Awareness [ABSTRACT FROM AUTHOR]

The use of Right dihedral method, Lisle graph, and Mohr diagram allows the analysis of the paleostress. Fault slip data were measured for eighteen data of two stations located within Chia Gara structure in Dohuk area in the High Folded Zone, Northern Iraq. Depending on Mohr diagram, Bott equation, and vertical thickness, the magnitudes of the paleostress at the time of the tectonic activity were determined. Firstly, Georient Software was used to estimate the orientation of the paleostresses (σ1, σ2 and σ3). Secondly, using the rupture -friction law, taking into account the depth of the overburden, the vertical stress (σv) was calculated to determine the magnitude of the paleostresses in the study area. The values in station one (hinge area, eight data) were σ1=7100, σ2=4121.5, and σ3=1143 bars, whereas the values in station two (the north limb of structure, ten data) were σ1=3740, σ2=1585, and σ3=570 bars. The high magnitudes of the principal stress axes may refer to the active tectonic events which led to the deformation of the area during the Mesozoic Era and the Tertiary period. The study area shows the existence of two types of the faults, the first type is the reactivated faults, the poles of which lie between the sliding line and Mohr envelope. The second type is the inactive faults, with poles lying on the great circle of Mohr diagram. [ABSTRACT FROM AUTHOR]

The Chilean territory is rich in evidence of the geological history of the Earth, presenting as the clearest evidence of this presence of the Andean Cordillera along its entire north-south extension. These conditions are not always understood by the country, relegating the geological wealth of the territory to a landscape backdrop condition, but without understanding the interdependence between geology and geomorphology and the historical, economic and cultural development of human societies. The creation of the UNESCO Global Network of Geoparks and the interest in developing one of these Geoparks in the commune of San Jose de Maipo presents a great opportunity to facilitate the interpretation processes that characterize ecotourism, while approaching this situation to the main domestic tourism issuing market and favor local development. This work explores both the fundamental concepts associated with the existence of Geotourism and Geoparks, as well as the conditions and opportunities presented to the community of San Jose de Maipo of reaching the creation of a Geopark in in the Cajon del Maipo area. [ABSTRACT FROM AUTHOR]

This paper sets the historical context for the Journal of Structural Geology when it was first published in 1979. The major advances in Structural Geology over the past 40 years are then highlighted. Finally, ten Grand Challenges for the next decade are nominated. • The history of Structural Geology up until the first issue of the Journal of Structural Geology in 1979 is highlighted. • Progress from 1979 to the present is summarised. • Some Grand Challenges for the future are outlined. [ABSTRACT FROM AUTHOR]

Abstract We present recent study results of the Lower Triassic conodont succession from the Ganxi and Jianshi areas of Enshi city, western Hubei Province, South China, which were situated on a carbonate ramp at the northeastern margin of the Upper Yangtze Platform. Therein, the uppermost Permian to Lower Triassic succession is well exposed and yielded abundant conodonts. A total of nine conodont zones are differentiated: (1) Clarkina yini Zone, (2) Clarkina meishanensis Zone, (3) Hindeodus changxingensis Zone, (4) Hindeodus parvus Zone, (5) Hindeodus postparvus Zone, (6) Clarkina planata Zone, (7) Neoclarkina aff. discreta Zone, (8) Neospathodus dieneri Zone, and (9) Novispathodus waageni Zone. The Ns. dieneri M1, Ns. dieneri M2, and Ns. dieneri M3 Subzones have also been distinguished within the Ns. dieneri Zone, and the Nv. waageni eowaageni and Nv. waageni waageni Subzones are recognizable within the Nv. waageni Zone in Jianshi. Most of the zones occur in succession, but the C. planata Zone is a local ecozone reflecting deeper water biofacies during H. postparvus Zone time. In the Jianshi section, the Permian–Triassic boundary is placed at Bed 136-2 based on the appearance of Hindeodus parvus immediately above the disappearance of Changhsingian taxa, while the Induan–Olenekian boundary (IOB) is drawn at Bed 225 + 40 cm based on the first appearance of Nv. waageni eowaageni within the upper range of the Ns. dieneri Zone indices. The Enshi conodont zones overall correlate well with those recognized elsewhere in South China and worldwide. Highlights • Nine conodont zones were established from the Enshi area. • The Permian–Triassic boundary is placed at Bed 136-2 in the Jianshi section. • The Induan–Olenekian boundary is drawn at Bed 225 + 40 cm in the Jianshi section. • The Enshi conodont zones overall correlate well with those recognized elsewhere. [ABSTRACT FROM AUTHOR]

Abstract On Earth, chemical weathering of basaltic rocks not only modulates the climate change, but also plays a crucial role on the ocean oxygenation and ecosystem evolution. Records of paleo-weathered crusts are a challenge to identify because they are obscured by subsequent alteration processes and buried by the newly formed volcanic lavas. However, late formed volcanic rocks theoretically could record previously weathered crust via their assimilation and fractional crystallization (AFC) processes. Here, we present a systematic study on major, trace elements and Sr-Nd-Mg isotopes in a suite of Changbaishan early formed basalts and late erupted trachytes from Northeast China. Detailed evidence of field observation, geochemical signature and rhyolite-MELTS simulations suggest that trachytes mainly originated from deep fractional crystallization of basaltic melts. The low abundant trachytes from the stratigraphic layer above the basalts display decoupled Mg Sr and Nd isotopes. δ26Mg and 87Sr/86Sr in trachytes range from −0.27 up to +0.94‰ (the heaviest isotopic composition ever reported for Mg in the igneous rocks) and 0.70490 to 0.71065, respectively, which are significantly elevated relative to that of their mantle source. However, they preserved mantle source-like 143Nd/144Nd (0.512584 to 0.512656) ratios. These unusual characteristics cannot be explained by thermal diffusion, fractional crystallization or simple crustal contamination processes. Specifically, δ26Mg correlates positively with SiO 2 and 87Sr/86Sr, and negatively with MgO, CaO, Al 2 O 3 , Sr and Nb/U indicators. The highly elevated Mg and Sr isotopes but limited Nd isotopic changes in trachytes require a component to be the relatively younger weathering residue of basaltic rocks. Taking this component as a wall rock endmember, the well-developed above correlations can be best modelled by AFC processes. This reflects that some trachytes in the aftermath of AFC processes almost fully lost their primary source characteristics, but inherited the intense chemical weathering signature of basalts. This event probably occurred in the middle Miocene as studies of paleosols showed humid and warm climate during that period after the initial eruption of Changbaishan basalts. Therefore, our study as a specific case for the first time provides an efficient way to explore paleo-weathering of basaltic crusts buried in the Earth's surface, through comprehensive investigating Mg, Sr and Nd isotopes of volcanic rocks developed in the late stage of a volcano cone. [ABSTRACT FROM AUTHOR]

The exceptionally preserved Chengjiang Biota (Yunnan, China) is significant for understanding the rapid development of complex animal-rich ecosystems during the evolutionary radiation of the Cambrian. However, the ecological signal provided by the fossils captured in this deposit may not reflect accurately the in-life community, with transport and decay of carcasses being the principal processes responsible for potential modification. The principal fossil-bearing interval (Maotianshan Shale Member, Yu'anshan Formation) is comprised of claystones of two distinct depositional origins: the “background” beds represent slow hemipelagic deposition into deep waters, while the “event” beds represent distal turbidites or storm-generated beds. Each bed type has a distinct fossil assemblage and preservation mode underscoring the importance of interpreting the palaeoenvironment of each bed type. Here, we interpret palaeo-redox conditions for both the background beds and the event beds by conducting a systematic geochemical study using iron speciation, δ 34 S py , δ 13 C carb, δ 13 C TOC and molybdenum abundance. These data are from the most complete core recovered from the Chengjiang fossiliferous units and allow us to distinguish redox conditions where the animals lived, and where they were buried and exceptionally preserved. Our results demonstrate that background beds were dominated by dysoxic conditions; here, a diverse sponge community tolerant of low-oxygen conditions lived. In contrast, the shallower shelf and offshore-transitional environments, where event beds were sourced, were almost persistently oxic, and it was here where the diverse Chengjiang Biota flourished. Thus, the Chengjiang sediments record two distinct palaeocommunities within the background and the event beds. The contrasting redox conditions in close spatial proximity likely facilitated the soft-bodied fossil preservation. Our findings provide a valuable case study in the necessity to understand ecological composition and exceptional preservation informed by environmental context. [ABSTRACT FROM AUTHOR]

Palaeo-exposure surfaces are common geologic features in the Cretaceous sedimentary record of the Middle East. Two important disconformity surfaces have influenced the Cenomanian-Turonian intervals of the Sarvak Formation in the Abadan Plain. These surfaces had substantial controls on reservoir quality of their underlying succession. In this study obtained data from macroscopic core descriptions, microscopic petrography, geochemical analysis, spectral gamma ray log signatures, and clay minerals frequency in three hydrocarbon fields are combined and used for interpretations. Dissolution, cementation and recrystallization are the main diagenetic features related to the disconformity surfaces. Intensity and development of these diagenetic alterations are highly dependent on depositional facies characteristics of the underlying sequences. In mud-dominated facies, the main diagenetic process is recrystallization, while the grain-dominated facies were highly subjected by dissolution and cementation. Based on the geochemical analysis, there is an increase in Al 2 O 3 , SiO 2 , Fe 2 O 3 , Al, Fe, Mn, and Rb content beneath the disconformities. In contrast, the Sr concentration displays a decreasing trend towards the disconformities. On spectral gamma ray logs, depletion of the uranium and high values of CGR/SGR and TH/U ratios are attributed to the meteoric diagenesis. In addition, obtained data from SEM and XRD analysis indicate that the montmorillonite is the most abundant clay mineral in uppermost part of the Sarvak Formation. It shows the highest concentration at the disconformity surfaces which can be quoted to the impact of meteoric diagenesis and development of palaeo-soil horizons. These results are used for reconstruction of diagenetic sequence of the upper Sarvak Formation in subsurface sections of the Abadan Plain. [ABSTRACT FROM AUTHOR]

The present study analyses the taphonomic features of recent small mammal bone and teeth accumulations recovered from pellets generated by Strix chacoensis in a Natural Protected Area in the central Monte Desert of Mendoza, Argentina. In order to identify the taphonomic signature of this predator in the formation of zooarchaeological and palaeontological accumulations, taxonomic profiles, relative abundances, bone breakage patterns and digestive corrosion were evaluated. Taphonomic results locate S. chacoensis in modification category 2 (intermediate). Although the general taphonomic patterns detected in the present study were similar to a typical owl pattern, some differences from that pattern were detected. This sample showed lesser relative abundances of skeletal elements, greater loss of teeth and a larger number of incisors modified by digestion than those generated by other strigiforms. The comparison with reported archaeological accumulations suggested that the small mammal remains recovered in some sites from the Monte Desert may correspond to the predatory activity of S. chacoensis. The identification of the action of S. chacoensis in archaeological and palaeontological small mammal bone and teeth accumulations is a promising tool to evaluate the conservation status of native forests in the past. [ABSTRACT FROM AUTHOR]

The Aurelian Mammal Age for peninsular Italy was introduced on the basis of faunal assemblages mainly recovered at sites along the Via Aurelia west of Rome. These sites exposed a set of sedimentary deposits currently attributed to the Aurelia and to the Vitinia Formations correlated with MIS 9 and MIS 7, respectively. In the present paper we reconstruct the geologic-stratigraphic setting in the western sector of Rome within the wider context of glacio-eustatically controlled, geochronologically constrained aggradational successions defined for this region. We present a chronostratigraphic study based on dedicated field surveys, that, combined with five new 40 Ar/ 39 Ar ages and eighteen trace-element and EMP glass analyses of volcanic products, allow us to revise age and correlation with the Marine Isotopic Stages for 10 sites out of 12 previously attributed to the Aurelia Formation and the Torre in Pietra Faunal Unit. In particular, we demonstrate a MIS 13/MIS 11 age for several sections along the Via Aurelia between Malagrotta and Castel di Guido. Based on this new geochronological framework, the first occurrences of Canis lupus and Vulpes vulpes in Italy are antedated to MIS 11, within the Fontana Ranuccio Faunal Unit of the Galerian Mammal Age, consistent with the wider European context. This contribution is intended as the groundwork for a revision of the Middle Pleistocene Mammal Ages of the Italian peninsula, according to the improved chronostratigraphy of the geologic sections hosting the faunal assemblages. [ABSTRACT FROM AUTHOR]

The early Paleozoic orogeny in South China created an important orogenic belt in East Asia, which possibly extends southwest to the Indochina block and northeast to the Korean Peninsula. Although this orogeny is interpreted as one of the examples of intraplate orogenesis in the world, the driver for the orogeny and its deformation details are poorly understood. In this study, we provide detailed structural analysis of the basement of the northeastern Cathaysia block (i.e., Chencai complex) with geochronological constraints. We combine previous studies with ours and obtain the following results. (1) The Chencai complex has experienced multiple metamorphic and deformation events since the early Paleozoic. The earliest deformation was northward thrusting at ca. 460-420 Ma (Dn+1a), which resulted in the thickening of the crust and coeval regional metamorphism (high-grade amphibolite to granulite facies). During the late stages of the orogeny (ca. 420-390 Ma, Dn+1b), the crust was extended and thinned; metamorphism and deformation during this stage erased the information from earlier stage(s). This early deformation (Dn+1) may have resulted from an intraplate orogeny and may have been a response to the Kuungan orogeny or Bhimphedian orogeny to the south, which caused the final assembly of Gondwana. The Jiangshan-Shaoxing fault belt was a sinistral ductile shear zone that formed to accommodate deformation between the Yangtze block and the eastern Cathaysia block. The Cathaysia block moved northward during the early Paleozoic and compressed the eastern Yangtze block. (2) During the Triassic, the Chencai complex experienced folding, forming northeast-southwest-trending close isoclinal folds as part of the regional thrust system along the southeastern margin of the Yangtze block at this time (Dn+2). (3) A group of northeast-southwest-trending thrusts cut the Chencai complex and placed it directly onto the Jiangshan-Shaoxing fault belt during the Late Jurassic (Dn+3). The main structures in the studied outcrops of the Chencai complex formed during the Triassic and Jurassic, not the early Paleozoic. (4) The fourth deformation event of the Chencai complex was a series of northwest-southeast-trending open folds that may have developed during the Cenozoic. [ABSTRACT FROM AUTHOR]

The first sedimentological characterization and correlation of onshore outcrop and offshore subsurface data (southern Columbus Basin) are presented for the paleo-Orinoco (Upper Miocene-Pliocene) shelf-margin prism, Trinidad Island, Trinidad and Tobago. The paleo-Orinoco River delta system and associated continental slope, which generated the 10-km-thick sedimentary prism, was a mixed river, tide, wave, and sediment-gravity flow system that tracked down to deep-water submarine fans. The analysis here includes: (1) an evaluation of delta-plain to deep-water turbidite sedimentary facies, which are seen in spectacular outcrops along the southwest, south, and southeast coasts of Trinidad Island, (2) well-log correlation of the same Upper Miocene-Pliocene strata across southern Trinidad and out to the southern part of the offshore Columbus Basin along an off-axis transect, because the main fairway into the most rapidly subsiding part of Columbus Basin is structurally complex, and few detailed data have been released for publication; and (3) use of published seismic data for reconstruction of clinoform morphology across the relatively undeformed segment of the margin, with quantitative sediment flux calculations and predictions. Paleo-Orinoco shelf-margin growth was generated by repeated (~<100 k.y. time scale) cross-shelf, regressive-transgressive transits (>100 km) of the Orinoco delta system, with internal variability in clinoform architecture and process-regime changes during shelf-margin construction. The Upper Miocene-Pliocene prism, with its linkage to the southern Columbus Basin and Columbus Channel, is composed of four progradational clastic wedges, each with a thickness up to 2 km, separated by well-known, Trinidadwide marine flooding intervals of similar extent, followed by an aggradational wedge with decreased clinothem thickness. The studied sedimentary prism spans an ~4 m.y. period and shows an overall rising shelf-edge trajectory, despite an overall and periodic falling eustatic sea level during this global icehouse period. The relationships among the Orinoco paleoflux, shelf-edge trajectory, and clinoform height and shape are discussed for a southeastern segment of the margin that is much less deformed than the main growth-faulted Columbus Basin. However, this off-axis segment was also subject to severe tectonic subsidence, as well as high-frequency sea-level, climate, and sediment supply changes. The estimated sediment flux percentage at the shelf edge shows a similar time trend to that of the well-imaged shelf-edge trajectory. The latter shows three long-term (~0.5 m.y.) trajectory changes, whereas the estimated sediment flux percentage at the shelf edge shows three supply pulses (with shelf-edge flux varying between 40% and 91% of original sediment discharge) through the early Pliocene, with nearly 76% of the sediment on average transported beyond the shelf edge to the deep-water areas, despite a relatively wide shelf. This sediment flux calculation, and particularly the occurrence of flat segments along the shelf-edge trajectory, predicts significant sediment bypass to slope or basin-floor fans on or beyond the toesets of the paleo-Orinoco shelf margin. At short time scales, the variation in the percentage of sediment budget bypassing the shelf edge depends on a series of shelf parameters. However, at geologic time scale, the total sediment flux bypassing the shelf edge is two thirds to three quarters of the total sediment budget. [ABSTRACT FROM AUTHOR]

In order to better understand the complex geologic history of the Mediterranean area, we have analysed evolutionary history, phylogeographic structure and molecular diversity of freshwater fishes belonging to the genus Telestes. As primary freshwater fishes distributed largely in the Mediterranean basin, this genus represents a suitable model system for investigating the historical biogeography of freshwater drainage systems in southern Europe. In this investigation we have included samples representing all Telestes species and based our analyses on one mitochondrial and one nuclear gene. We have investigated phylogenetic structure inside the genus Telestes, estimated divergence times, reconstructed ancestral distribution ranges and described intraspecific molecular diversity. Diversification of Telestes started in the Early Miocene, when the ancestors of T. souffia, lineage comprising T. croaticus and T. fontinalis, and the one comprising T. pleurobipunctatus and T. beoticus got isolated. The remaining species are genetically more closely related and form a common cluster in the recovered phylogenetic trees. Complex geological history of southern Europe, including formation of continental bridges, fragmentation of landmass, closing of the sea corridor, local tectonic activities, led to complicated biogeographical pattern of this genus, caused by multiple colonization events and passovers between ancient rivers and water basins. Especially pronounced diversity of Telestes found in the Adriatic watershed in Croatia and Bosnia and Herzegovina is a consequence of a triple colonization of this area by different lineages, which led to an existence of genetically distinct species in neighboring areas. Significant intraspecific structuring is present in T. souffia, T. muticellus, T. croaticus and T. pleurobipunctatus. Besides in well-structured species, elevated levels of genetic polymorphism were found inside T. turskyi and T. ukliva, as a consequence of their old origin and unconstrained evolutionary history. [ABSTRACT FROM AUTHOR]

In the Quebec Appalachians, the Laurentian continental margin (Humber Zone) and adjacent oceanic domain (Dunnage Zone) were amalgamated during the Ordovician Taconian orogeny. The Dunnage Zone includes ophiolites and overlying synorogenic deposits of both the Saint-Daniel Me ´lange and Magog Group. The latter consists of a ~3 km-thick pile of sandstone, felsic volcaniclastic rocks and graphitic slate at the base (Frontière, Etchemin and Beauceville formations) overlain by a ~7 km-thick turbiditic ?ysch sequence, constituting the Saint-Victor Formation. The maximum upper age limit of the Magog Group was considered to be Darriwilian based on graptolite fauna. This was proven consistent with a 462+5/-4 Ma (U-Pb ID-TIMS) from a felsic tuff of the Beauceville Formation, but contradicts a detrital zircon U-Pb age of 424 ± 6 Ma recently measured in the Saint-Victor Formation. A new detrital zircon U-Pb geochronology study (HR-LA-ICP-MS and ID-TIMS), focused on the Saint-Victor Formation, yields young detrital populations that suggest that the Saint- Victor Formation is not exclusively Ordovician and extends into the Silurian, as indicated by a maximum age of sedimentation around 430 Ma. Detrital zircon U-Pb geochronology associated with fossil age constraints and stratigraphic correlations in adjacent areas attest that the Saint-Victor Formation should be considered as an upper Magog Group sequence that is separated from lower units (the Frontière-Etchemin-Beauceville formations) by an unconformity corresponding to a sedimentary hiatus of ≤ 10 m.y. Regional tectonic considerations imply that the Magog Group evolved from a syn-Taconian forearc basin in Middle-Late Ordovician time to a syn-Salinic peri-continental basin in early Silurian time. Several NW and SE erosional sources are invoked for the sedimentation of the Magog Group, evolving from the erosion of both the southern Quebec ophiolites and adjacent sedimentary rocks of the Laurentia margin to the NW, and volcanic arc rocks of the Ascot Complex, Shelbourne Falls and Bronson Hill massifs to the SE. Potential sources for ca. 430 Ma zircons found towards the top of the Saint-Victor sequence are the Silurian Frontenac Formation and the East Inlet granitic pluton, both located in the vicinity of the Quebec-Maine border. [ABSTRACT FROM AUTHOR]

Buried channel systems are important sedimentary repositories for documenting environmental changes in response to eustatic events. Here we investigate the morphology, infilling structure, and evolutionary history of buried channel systems offshore of Long Beach Island, New York, through dense, ultra-high resolution seismic profiles. On the basis of stratigraphic superposition, characteristic of bounding seismic surfaces, seismic geometries as well as previous studies, we identify four seismic units interpreted, top-to-bottom, as: Holocene marine sand sheet (SU1); Pleistocene-Holocene channel system (SU2); younger Pleistocene outwash lobe (SU3); and older Pleistocene outwash sediments (SU4). Two sets of channel systems are observed, one shallower (SU2) and the other deeper (inside SU4). The shallower channel system, consists of both fluvial/glaciofluvial incised valley and tidal channels/inlets, incised during or near Last Glacial Maximum and was filled during the ensuing Pleistocene-Holocene transgression, associated closely with estuarine process. The channel fill sediments, the only preserved stratigraphic record of the last sea-level cycle around this area, comprises six seismic facies, which are interpreted as: fluvial/glaciofluvial lag deposits (SF1); relict estuarine complex (SF2); retrogradational barrier system (SF3); later-formed bayhead delta (SF4); an undetermined facies which has the potential to be either barrier, central basin, bayhead delta deposits, or their complex inside the incised valley (SF5); and tidal channel/inlet/flat complex outside the valley (SF6). These facies are bounded by either ravinements (bay flooding, tidal, shoreface) or sedimentary surfaces. This interpretation and seismic geometry reveal evolution of the shallower channel system experienced (1) fluvial/glaciofluvial incision and lag preservation, (2) back-filling of estuarine complex (bayhead delta and central basin sediments), (3) landward rollover of barrier system (river mouth complex), (4) progradation of a new bayhead delta that onlaps the barrier sediments, and (5) reworking and partial erosion resulting in the transgressive ravinement (T surface). This suggests that the estuarine process was the primary factor that resulted in the infilling structure. Our results indicate the deeper channel system comprises two discontinuous channel segments. Although several seismic horizons and facies are identifiable in association with this channel system, we are unable with these data to determine if these segments are connected, nor can we confidently determine the origin and filling structure of the deeper channel system. [ABSTRACT FROM AUTHOR]

This study is based on zircon U-Pb ages of 12 volcanic ash layers and volcanogenic sandstones from two deep water sections with conformable and continuous formational Permian–Triassic boundaries (PTBs) in the Nanpanjiang Basin (South China). Our dates of single, thermally annealed and chemically abraded zircons bracket the PTB in Dongpan and Penglaitan and provide the basis for a first proof-of-concept study utilizing a Bayesian chronology model comparing the three sections of Dongpan, Penglaitan and the Global Stratotype Section and Point (GSSP) at Meishan. Our Bayesian modeling demonstrates that the formational boundaries in Dongpan (251.939±0.030Ma), Penglaitan (251.984±0.031Ma) and Meishan (251.956±0.035Ma) are synchronous within analytical uncertainty of ∼40ka. It also provides quantitative evidence that the ages of the paleontologically defined boundaries, based on conodont unitary association zones in Meishan and on macrofaunas in Dongpan, are identical and coincide with the age of the formational boundaries. The age model also confirms the extreme condensation around the PTB in Meishan, which distorts the projection of any stratigraphic points or intervals onto other more expanded sections by means of Bayesian age–depth models. Dongpan and Penglaitan possess significantly higher sediment accumulation rates and thus offer a greater potential for high-resolution studies of environmental proxies and correlations around the PTB than Meishan. This study highlights the power of high-resolution radio-isotopic ages that allow a robust intercalibration of patterns of biotic changes and fluctuating environmental proxies and will help recognizing their global, regional or local significance. [ABSTRACT FROM AUTHOR]

Paleosols, surface soils, mammal bone remains of Late Pleistocene and Holocene deposits of the rock shelter Svetly were studied. The joint analysis of paleontological and paleosol data was carried out. The paleoenvironment underwent considerable transformation, which resulted in changes in type of soil formation and in the structure of the mammal community. Cryoarid conditions with mammoth complex mammals of Late Pleistocene layer changed to warmer and more humid conditions with spread of open landscapes, along with forest biotope formation. The most favorable conditions in terms of heat and moisture supplies continued during the Middle Holocene, resulting in formation of dark humus horizons. By the late stage of this epoch, taiga fauna had formed. Later conditions become cooler. Chronological heterogeneity of bone remains in the upper layer is caused by a complex genesis of local sediments. Staged process of sedimentation resulted in polygenetic soil profiles. Common structure of deposits is indicative of the general trend in the paleoenvironmental evolution. The study of separate layers within the soil profiles largely reveals the concurrent nature of soil and fauna evolutions. [ABSTRACT FROM AUTHOR]

Variations in the O, Sr, Nd, and Hf isotopic compositions in rocks of various ages, minerals, and mantle temperature in the geological history are considered. Two periods in the Earth's history are studied: the beginning of the formation of the planet until the turn of (3.4) 2.7-2.5 Ga and the tectonic movement period in the last 2 Ga, and also the transitional period within 2.7-2.0 Ga. [ABSTRACT FROM AUTHOR]

The distribution of large and superlarge mineral deposits (LSMD) of the most important raw materials is correlated with supercontinent cycles in the geological history of the Earth. The latter displays the distinct correlation between metallogenic activity and cyclic global endogenous processes reflected in quasi-regular cycles, which result eventually in the assembly and breakup of supercontinents. In the framework of these cycles, the maximums in the LSMD assembly coincide with periods of intense growth of the subcontinent crust owing to growth of the matter originated from juvenile sources (Kenoran, Columbian cycles) or with epochs of intense recycling of the mature crust (Pangean, Amasian cycles). The Rodinian cycle with minimum activity of these both endogenous processes demonstrates simultaneously minimum metallogenic activity. The distribution of most LSMD types generally follows these main tendencies. [ABSTRACT FROM AUTHOR]

The Lugokan ore cluster is located in the southeastern part of Transbaikalia within the Aga-Borzya structural-formational zone of the Mongol-Okhotsk orogenic belt. The Ar/Ar dating of K-bearing minerals of syngenetic to ore parageneses has been carried out applying stepwise heating technique: it has been demonstrated that the earliest gold-ore mineral associations are Au-pyrite-arsenopyrite (163 ±1.9 Ma) and Au-chalcopyrite (160 ±2 Ma). The later parageneses encompass the Au-polymetallic (156.3 ± 1.8 Ma) and Au-Bi (155.9 ± 4.5 Ma) one. By their ages and position in the general scheme of the Late Jurassic magmatism of Eastern Transbaikalia, the Lugokan's ore cluster gold-bearing mineral associations corresponds to the time of intrusion of the Shakhtama pluton (161 Ma) and the Porphyry Complex (159-155 Ma). [ABSTRACT FROM AUTHOR]

The concept of the niche is fundamental to ecology and palaeoecology, and an extensive body of scientific literature exists on the subject Here we discuss how recent palaeontological studies, particularly those focusing on species' niche dynamics through time, continue to integrate palaeoecology with macroevolutionary theory. [ABSTRACT FROM AUTHOR]

The Hakusan volcano, central Japan, is located in a region where two subducting plates (the Pacific Plate and the Philippine Sea Plate) overlap near the junction of four plates adjacent to the Japanese Islands (the Pacific Plate, the Philippine Sea Plate, the Eurasia Plate, and the North American Plate). The Hakusan volcano consists of products from four major volcanic episodes: Kagamuro, Ko-hakusan, and Shin-Hakusan I and II. To date the eruption events of the Hakusan volcano we applied thermoluminescence and fission track methods. 238U(234U)-230Th disequilibrium and 206Pb/238U methods were applied to date the zircon crystallization ages for estimating the magma residence time before the eruptions. The eruption ages we obtained are ca 250 ka for Kagamuro, ca 100 ka and ca 60 ka for Ko-Hakusan, ca 50 ka for Shin-Hakusan I, and <10 ka for Shin-Hakusan II. They are concordant with previous reports based on K-Ar dating. Some of the pyroclastic rocks, possibly originating from Shin-Hakusan II activities, are dated to be ca 36 ka or 50 ka, and belong to the Shin-Hakusan I activity. The zircon crystallization ages show several clusters prior to eruption. The magma residence time was estimated for each volcanic activity by comparing the major crystallization events and eruption ages, and we found a gradual decrease from ca. 500 ky for the Kagamuro activity to ca. 5 ky for the Shin-Hakusan II activity. This decrease in residence time may be responsible for the decrease in volume of erupted material estimated from the current topography of the region. The scale of volcanic activity, which was deduced from the number of crystallized zircons, is more or less constant throughout the Hakusan volcanic activity. Therefore, the decrease in magma residence time is most likely the result of stress field change. [ABSTRACT FROM AUTHOR]

The relationship between the areas of Southeast Asia and the West Pacific region is still debated because of their complex historical geology and the enormous diversity of taxa. Cladistic methods have previously been used to reconstruct the relationships between areas in the region but never with such a high number of unrelated taxa (35). We use a compilation of phylogenies to investigate area relationships among Southeast Asia and the West Pacific region, run the comparative analysis with LisBeth [based on three-item analyses (3ia)] and compare the results with recently published geological reconstructions of the region. We discuss the relevance of such an approach to the interpretation of general pattern. The two questions addressed are: (1) is there an emerging common pattern; and (2) how to explain actual distributions of taxa in Southeast Asia and the West Pacific region. Three-item analysis found 27 optimal trees. An intersection tree reconstructed from the common three-area statements had an overall retention index of 84.8% and retrieved 13 nodes with two major branches compatible with a separation between Southeast Asia and the West Pacific region (i.e. congruent with some geological reconstructions). Any congruent patterns revealed by the combination of unrelated taxa should reflect a common cause. The extraction of information on area relationships contained in phylogenetic analyses of taxa consists of testing for area homologues. We obtained the tree from this region based on an empirical dataset which we hope will contribute to new insights into area classification in the region. [ABSTRACT FROM AUTHOR]

The increase in detrital geochronological data presents challenges to existing approaches to data visualization and comparison, and highlights the need for quantitative techniques able to evaluate and compare multiple large data sets. We test five metrics commonly used as quantitative descriptors of sample similarity in detrital geochronology: the Kolmogorov-Smirnov (K-S) and Kuiper tests, as well as Cross-correlation, Likeness, and Similarity coefficients of probability density plots (PDPs), kernel density estimates (KDEs), and locally adaptive, variable-bandwidth KDEs (LA-KDEs). We assess these metrics by applying them to 20 large synthetic data sets and one large empirical data set, and evaluate their utility in terms of sample similarity based on the following three criteria. (1) Similarity of samples from the same population should systematically increase with increasing sample size. (2) Metrics should maximize sensitivity by using the full range of possible coefficients. (3) Metrics should minimize artifacts resulting from sample-specific complexity. K-S and Kuiper test p-values passed only one criterion, indicating that they are poorly suited as quantitative descriptors of sample similarity. Likeness and Similarity coefficients of PDPs, as well as K-S and Kuiper test D and V values, performed better by passing two of the criteria. Cross-correlation of PDPs passed all three criteria. All coefficients calculated from KDEs and LA-KDEs failed at least two of the criteria. As hypothesis tests of derivation from a common source, individual K-S and Kuiper p-values too frequently reject the null hypothesis that samples come from a common source when they are identical. However, mean p-values calculated by repeated subsampling and comparison (minimum of 4 trials) consistently yield a binary discrimination of identical versus different source populations. Cross-correlation and Likeness of PDPs and Cross-correlation of KDEs yield the widest divergence in coefficients and thus a consistent discrimination between identical and different source populations, with Cross-correlation of PDPs requiring the smallest sample size. In light of this, we recommend acquisition of large detrital geochronology data sets for quantitative comparison. We also recommend repeated subsampling of detrital geochronology data sets and calculation of the mean and standard deviation of the comparison metric in order to capture the variability inherent in sampling a multimodal population. These statistical tools are implemented using DZstats, a MATLAB-based code that can be accessed via an executable file graphical user interface. It implements all of the statistical tests discussed in this paper, and exports the results both as spreadsheets and as graphic files. [ABSTRACT FROM AUTHOR]

This work presents the first isotope-geochronological data obtained for granitoid series of the Arminskii block of Central Sikhote Alin: Tatibi gabbromonzodiorite and Olgino leucocratic granite. Every series is characterized by a certain structural position and timing of the formation of ore mineralization. The Tatibi series is characterized by the presence of gold-ore occurrences including the potential Glukhoe goldore occurrence. Granitoids of the Olgino series comprise known tin-sulfide ore occurrences. The conditions for the generation of each series of rocks were revealed on the basis of geochronological-isotope data. [ABSTRACT FROM AUTHOR]

The response of temperature to CO2 change (climate sensitivity) in the geologic past may help inform future climate predictions. Proxies for CO2 and temperature generally imply high climate sensitivities: ≥3 K per CO2 doubling during ice-free times (fast-feedback sensitivity) and ≥6 K during times with land ice (Earth-system sensitivity). Climate models commonly underpredict the magnitude of climate change and have fast-feedback sensitivities close to 3 K. A better characterization of feedbacks in warm worlds raises climate sensitivity to values more in line with proxies and produces climate simulations that better fit geologic evidence. As CO2 builds in our atmosphere, we should expect both slow (e.g., land ice) and fast (e.g., vegetation, clouds) feedbacks to elevate the long-term temperature response over that predicted from the canonical fast-feedback value of 3 K. Because temperatures will not decline for centuries to millennia, climate sensitivities that integrate slower processes have relevance for current climate policy. [ABSTRACT FROM AUTHOR]

Kettneraspis? prescheri sp. nov. is described from the Ihandar Formation at Jbel Issoumour, SE Morocco. Relationships of the morphologically similar Kettneraspis Prantl & Přibyl and Leonaspis Richter & Richter are discussed. Previous diagnoses in the literature are no longer considered to be valid. [ABSTRACT FROM AUTHOR]

A volcanic tuff 1.0 m above the base of the Triebenreuth Formation in the Franconian Forest provides the first precise and biostratigraphically bracketed date within the traditional Middle Cambrian. The first illustration of fossils from the Triebenreuth Formation in this report and their discussion allow a more highly refined correlation within the Middle Cambrian. A weighted mean 206Pb–238U date of 503.14±0.13/0.25/0.59 Ma on zircons from this subaerial pyroclastic tuff was determined by U–Pb chemical abrasion isotope dilution mass spectrometry (CA-TIMS) techniques. At c. 6.0–7.0 Ma younger than the base of the traditional Middle Cambrian in Avalonia, the new West Gondwanan date from east-central Germany suggests that estimates of 500 Ma for the base of the traditional Upper Cambrian and 497 Ma on the base of the Furongian Series may prove to be too ‘old’. Biostratigraphically well-bracketed dates through most of the Middle Cambrian/Series 3 and below the upper Upper Cambrian/upper Furongian Series do not exist. An earlier determined 494.4±3.8 Ma date from the Southwell Group of Tasmania may actually prove to be a reasonable estimate for the age of the base of the traditional Upper Cambrian. Until high precision dates are determined on the base of the traditional Upper Cambrian and base of the Furongian Series, the rates of biotic replacements and geological developments and the durations of biotic zones in the Middle/Series 3 and Upper Cambrian/Furongian Series remain as ‘best guesses’. [ABSTRACT FROM AUTHOR]

Silicoflagellate double skeletons are commonly considered to be pre-division stages, even though their life cycle is only partially resolved, especially with respect to reproduction. Double skeletons of the modern silicoflagellate genera Dictyocha Ehrenberg, Distephanus Stöhr, and Octactis Schiller are for the first time examined in detail by scanning electron microscopy in order to improve our understanding of how skeletal morphology relates to paired skeletons. A number of genus-specific mechanisms enable sibling skeletons to be held together at their abbasal surfaces, including a zig-zag design of the basal ring achieved via apical structure, strut attachment and pike rotation (in Distephanus and Dictyocha ), and the presence of organic material binding the generally planar basal rings (in Octactis ). Contrary to what is generally understood, the siblings are not mirror images of one another. Instead, the triple junctions formed by the skeletal elements of each apical structure are transposed across the middle of the dividing cell to produce a copy with the same rotation. Thus, two dome-shaped skeletons represent halves of a more spherical design, which suggests that the role of the silicoflagellate basal ring is to enable double skeleton formation, but the full implications of this have yet to be explored. Although the purpose of double skeleton formation in silicoflagellates remains unclear, observations from the fossil record indicate that differences in the relative alignment of doublet members can have a high significance for phylogeny. Differences in the doublet structure of living silicoflagellates call for a combined biological and geological perspective of the utility of maintaining Dictyocha, Distephanus and Octactis as separate genera. [ABSTRACT FROM AUTHOR]