The discovery of a new specimen of Portunus withersi (Glaessner 1933) from the Lower Miocene Qom Formation in the Vartun section, north of Isfahan (Central Iran), contributes to our knowledge of this portunid species, to which most fossil portunids found in the Miocene of Iran have been attributed. New images of the holotype are also presented herein. The Miocene decapod fauna of Iran, exhibiting a clear Indo-Pacific affinity, reflects an emerging loss of faunal homogeneity between the decapod communities on either side of the Tethys Realm. This differentiation is related to the progressive closure of the Tethys Seaway, which interrupted the connection between the proto-Mediterranean and Paratethys seas and the Indian Ocean. This stands in contrast to the relative faunal homogeneity observed during the Paleogene, as evidenced by the presence—on both sides of the Tethys Realm—of genera such as Zanthopsis M’Coy 1849, Palaeocarpilius A. Milne-Edwards 1862, or Lophoranina Fabiani 1910, among others, and even species such as Retrocypoda almelai Vía Boada 1959.
Abstract Lavas erupted in Continental Flood Basalt (CFB) provinces are not primary magmas; they are differentiated products that result from large volumes of melt migrating and stalling in the lithosphere prior to eruption, resulting in complex liquid lines of descent. Geochemical models can be used to constrain the various influencers of magma differentiation (recharge, assimilation, fractional crystallization (FC), eruption, and mixing). Temporal constraints for changes in plumbing system dynamics are recorded in the petrography and stratigraphy of the erupted lava flows. This study focuses on the flow‐stratigraphy preserved within the Oligocene Ethiopian low‐Ti flood basalt province, located on the NW Ethiopian Plateau. We present new bulk rock geochemistry from 107 lavas and interpret these data within a petrostratigraphic framework. Our model results suggest that both a deep (∼0.6 GPa) and shallow (<0.2 GPa) magmatic system are active throughout the main phase of volcanism. Our recharge evacuation assimilation and fractional crystallization models (REAFC) show that during the main phase of magmatism evacuation from both the deep (65%) and shallow (55%) systems reached an apex. During the terminal phases, magma evacuation from the deeper system ceases while evacuation from the shallow system is much reduced (25%). The degree of crustal contamination predicted by REAFC (4%–10%) is lower than previous estimates determined for this region using assimilation with FC only models (12%–25%). Our study highlights the importance of evaluating petrography while interpreting geochemical models in CFB.
Abstract The iso‐ or diachronous character of a geologic unit is scale‐dependent, especially for time‐specific facies. The Usseln Limestone is a Late Devonian time‐specific facies from Germany, occurring immediately below the Lower Kellwasser black shale. Here, we investigate whether cm‐scale rhythmical bands within the Usseln Limestone are correlatable across its depositional basin. Its facies were studied at three locations ca. 50 km apart, representing different depositional settings. Its cm‐scale alternations in lithological facies and elemental content (μXRF) form an excellent target for correlations on millennial timescales. Correlation attempts failed to converge to a solution at the cm‐scale of individual rhythmites. Dynamic Time Warping, however, provided convincing correlations at the dm‐scale, supporting its use as a high‐resolution correlation tool. The Usseln Limestone base may be diachronous, but the top is likely isochronous. This finding is in agreement with sudden basin‐wide black shale deposition at the onset of the Kellwasser Crisis.
Abstract A new species of the extant staphylinid genus Vicelva Moore & Legner, V. rasilis sp. nov., is reported from mid‐Cretaceous Kachin amber of northern Myanmar. Vicelva rasilis is distinguishable from extant members of Vicelva by the smoother dorsal surface of head, pronotum and elytra, less prominent median projection of clypeus, unnotched mesal edge of mandibles, semiglabrous antennomere 6, and longer tarsomere 1. The pollen‐containing coprolite attached to the beetle and the crystals within the beetle body provide valuable information about the biology and taphonomy of the fossil.
Pierluigi Pieruccini, Luca Forti, Beniamino Mecozzi
et al.
Abstract During the last century, Grotta Romanelli (Southern Italy) has been a reference site for the European Late Pleistocene stratigraphy, due to its geomorphological setting and archaeological and palaeontological content. The beginning of the sedimentation inside the cave was attributed to the Last Interglacial (MISs 5e) and the oldest unearthed evidence of human occupation, including remains of hearths, was therefore referred to the Middle Palaeolithic. Recent surveys and excavations produced new U/Th dates, palaeoenvironmental interpretation and a litho-, morpho- and chrono-stratigraphical reassessment, placing the oldest human frequentation of the cave between MIS 9 and MIS 7, therefore embracing Glacial and Interglacial cycles. These new data provide evidence that the sea reached the cave during the Middle Pleistocene and human occupation occurred long before MISs 5e and persisted beyond the Pleistocene- Holocene boundary.
J. Acevedo, G. Fernández-Viejo, S. Llana-Fúnez
et al.
<p>The cross-correlation of ambient noise records registered by seismic networks has proven to be a valuable tool to obtain new insights into the
crustal structure at different scales. Based on 2 to 14 <span class="inline-formula">s</span> period Rayleigh and Love dispersion data extracted from the seismic ambient noise
recorded by 20 three-component broadband stations belonging to two different temporary experiments, we present the first (i) upper-crustal
(1–12 <span class="inline-formula">km</span>) high-resolution shear wave velocity and (ii) radial anisotropy variation models of the continental crust in NW Iberia. The area
of study represents one of the best-exposed cross sections along the Variscan orogen of western Europe, showing the transition between the external
eastern zones towards the internal areas in the west. Both the 2-D maps and an E–W transect reveal a close correspondence with the main geological
domains of the Variscan orogen. The foreland fold-and-thrust belt of the orogen, the Cantabrian Zone, is revealed by a zone of relatively low shear
wave velocities (2.3–3.0 <span class="inline-formula">km s<sup>−1</sup></span>), while the internal zones generally display higher homogeneous velocities
(<span class="inline-formula">></span> 3.1 <span class="inline-formula">km s<sup>−1</sup></span>). The boundary between the two zones is clearly delineated in the models, depicting the arcuate shape of the orogenic
belt. The velocity patterns also reveal variations of the elastic properties of the upper crust that can be linked to major Variscan structures,
such as the basal detachment of the Cantabrian Zone, the stack of nappes involving pre-Variscan basement, or sedimentary features such as the
presence of thick syn-orogenic siliciclastic wedges. Overall, the radial anisotropy magnitude varies between <span class="inline-formula">−</span>5 % and 15 % and increases
with depth. The depth pattern suggests that the alignment of cracks is the main source of anisotropy at <span class="inline-formula"><</span> 8 <span class="inline-formula">km</span> depths, although the
intrinsic anisotropy seems to be significant in the West Asturian–Leonese Zone, the low-grade slate belt adjacent to the Cantabrian Zone. At
depths <span class="inline-formula">></span> 8 <span class="inline-formula">km</span>, widespread high and positive radial anisotropies are observed, which we attribute to the presence of subhorizontal
alignments of grains and minerals in relation to the pre- or syn-orogenic deformation associated with the Variscan orogenesis.</p>
The phenomenon of insular dwarfism in proboscideans is particularly well represented on the Siculo-Maltese Palaeoarchipelago, an island group on which a species complex of palaeoloxodont elephants evolved during the Middle-Late Pleistocene. This likely included three species from Malta, four from Sicily (and possibly its palaeo-islands), and one from Favignana Island, ranging in size from the 1 m-tall <i>Palaeoloxodon falconeri</i> to continental-sized 4m-tall <i>P. antiquus</i>. However, our understanding of the causes for extreme differences in body size among insular samples in such a small geographic region is still limited. Here, I document the full range in size of elephants from the palaeoarchipelago, and discuss the reasons for size differences on the three islands in time and space in relation to predation, competition, resource limitation, accelerated life history, and duration of isolation. Differences in size between larger and smaller Sicilian elephants from Luparello Fissure, as well as possibly also in <i>P.</i> ex gr. <i>P. mnaidriensis</i> from Puntali Cave, San Teodoro Cave, and Favignana Island, may relate to the duration of isolation, or alternatively environmental stressors associated with the Last Glacial Maximum in the case of the Favignana elephant. Additionally, small but significant differences in size observable in Middle Pleistocene <i>P.</i> ex gr. <i>P. falconeri</i> from different localities on Sicily, as well as in Maltese <i>P. ‘melitensis’</i> may also relate to duration of isolation, highlighting the need for better geochronological data in order to better distinguish macro-ecological causes driving body size change from more subtle effects relating to duration of isolation.
Detailed sedimentological studies of the university main campus of São Paulo city, Brazil, revealed a significant unconformity at the top of the Cenozoic sedimentary deposits of the São Paulo Formation. This unconformity is overlapped by Quaternary sediments which can be traced in 1:20,000 scale and are here named as the Bosque Formation. This unit is characterized by poorly sorted mud deposits and very fine-grained red sand with granule- and pebble-sized clasts of the underlying São Paulo Formation. Furthermore, it overlies topographic highs of the Precambrian basement, and is laterally interfingered with fluvial terraces; it is eroded by the modern river at the lower reaches of the outcrops. The Bosque Formation records sedimentation characterized by a widespread mudflow that overlays old alluviums sediments, and was likely deposited during the beginning of the Holocene.
The Chang’E-4 mission has been exploring the lunar farside. Two scientific targets of the rover onboard are (1) resolving the possible mineralogy related to the South Pole-Aitken basin and (2) understanding the subsurface processes at the lunar farside. Publications to date that are based on the reflectance spectra and radar data obtained by the rover have shown a persistent inconsistency about the local stratigraphy. To explain both the abnormal surface topography at the landing site and the unexpected radargram observed by the rover, the Alder crater has been frequently reported to be older than the mare basalts at that landing site. However, this argument is not supported by earlier geological mapping nor recent crater statistics. Resolving this controversy is critical for a full understanding of the geological history of the landing area and for correct interpretations of the scientific data returned. Employing detailed crater statistics, rigorous statistical analyses, and an updated crater chronology function, this study is determined to resolve the relative ages of the Alder crater, Finsen crater, and the mare basalts on the floor of Von Kármán. Our results reveal that while background secondaries and local resurfacing have widely occurred in the study area, affecting age determinations, the statistics are significant enough to conclude that the Alder crater is the oldest among the three targets. This independent constraint is consistent with both the crosscutting relationships of different terrains in this area and global stratigraphic mapping. Our results exclude Alder as a possible contributor of the post-mare deposits at the landing site, appealing for a more systematic stratigraphy study to resolve the provenances of these deposits.
The paper discusses the directions of hydrogeochemical researches used to solve actual problems of the oil and gas industry: assessment of the oil and gas potential of territories, localization of oil and gas trap, prediction of the phase composition of hydrocarbon fields, control the development process of hydrocarbon fields, etc. Based on the literature data, the analysis and systematization of the main hydrogeochemical indicators of groundwater with oil and gas prospecting significance, as well as used already at the stage of development of oil and gas fields, have been carried out. The most efficiency of the application of hydrogeochemical researches in oilfield practice is achieved with the integrated use of various indicators. On the example of researches of the oil and gas potential of Sakhalin Island, it is shown that the hydrogeochemical data of the middle of the 20th century, obtained by outdated chemical analytical methods, cannot always be considered reliable. In this regard, additional researches are required to update the relevant hydrogeochemical data in this region.
LUNG S. CHAN, ALESSANDRO MONTANARI, WALTER ALVAREZ
We have determined the magnetostratigraphy in eight Upper Cretaceous to Eocene sedimentar y sections in the Umbria and Marche Region of the Northern Apennines, Italy. Paleomagnetic samples were collected at roughly 1 m intervals from the sections studied. Both alternating field and thermal demagnetization were carried out. Microfossils in the specimens were studied to facilitate identification of the magnetic polarity intervals. We have used the combined paleomagnetic and paleontological results in conducting a high—resolution correlation and in reconstructing the paleobasin tectonic history. The magnetostratigraphic results from this study contribute to the understanding of three aspects
Research subject. The most frequently utilized fundamental notions in stratigraphy are discussed: concrete section, composite section, the stratigraphic scale, the biochronologic scale, the International Stratigraphic Scale.Materials and methods. The conventional content of these concepts is analyzed. The logical invalidity and negative consequences of the identification of subdivisions of the stratigraphic scale and subdivisions of a section are shown. The study of a section provides a way of obtaining information about the stratigraphic sequence of rock formation and the distribution of evidence of the events included in them, which are necessary for constructing stratigraphic scales. The close connection of the source of the actual data and results of its stratigraphic interpretation is the reason for the traditional identification of the subdivisions of the stratigraphic scale and subdivisions of a particular section.Results. The biochronologic scale inherits from a section the time sequence of occurrences of species of a certain group of organisms selected as the basis of a scale. However, special features of the evolutionary development of organisms do not depend on the composition of the containing deposits and the method of the separation of sedimentary rock sequences. This development makes it possible during the study of many specific sections to establish homotaxis in the distribution of fossils, i.e., to build a biochronologic scale. Thus, the understanding of the scale is a model of the biochronologic calculation of geological time. Like any model, a scale cannot be identical to what it simulates.Conclusion. A precise differentiation of the scale and a section is the basis for drawing correct stratigraphic conclusions. A zone is the smallest subdivision of the biostratigraphic scale. Zones are not divided into parts, are discrete (between adjacent zones there are no time passages), equivalent and are characterized by only the place which it occupies on the scale. The construction of a zone scale precedes the establishment of the material equivalent of the zone - of a stratozone - in the section. Any part of a stratozone is dated by the complete zone. The identification of the zonal scale with a sequence of stratozones in the section does not make it possible to understand the minimum dimensionality of a zone subdivision. The International Stratigraphic Scale (ISS) is defined, based on domestic stratigraphic codes and on foreign reference books, as a stratigraphic sequence of rocks (geological bodies) in total volume without passages and overlaps. In this treatment the ISS is not the scale, but is a complete (composite) geological section of the earth’s crust. The biostratigraphic scale serves as a tool of correlation. The ISS gives only the name of that subdivision, with which a concrete section is compared, and the geological age of the deposits of this section is designated by this name.
Engineering geology. Rock mechanics. Soil mechanics. Underground construction
Alexis Del Pilar-Martínez, Angel F. Nieto-Samaniego, Susana A. Alaniz-Alvarez
et al.
The Mesa Central (MC) of Mexico presents a noticeable feature as is the three-dimensional (3D) deformation of Cenozoic volcanic rocks. To figure out when this unusual deformation began, we constructed a geological map at 1:100,000 scale, with detailed stratigraphy, and thirteen new U-Pb ages in the southern MC. The mapped area is dominated by silicic volcanic rocks with ages from ca. 34.4 Ma to ca. 23.5 Ma affected by coeval normal faulting. An angular unconformity evidences a shift in the deformation style that occurred around 30 Ma, from an NW-trending fault system in domino-style to a polymodal fault system, which also temporally coincided with the emplacement of lava dome complexes. The structural and stratigraphic data give new insight for understanding how the polymodal fault system developed in the southern MC, suggesting that the change in the deformation and volcanism regime played an important role.
In the Spanish Pyrenees, the Sant Corneli-Bóixols
thrust-related anticline displays an outstandingly preserved growth strata
sequence. These strata lie on top of a major unconformity exposed at the
anticline's forelimb that divides and decouples a lower pre-folding unit
from an upper syn-folding one. The former consists of steeply dipping to
overturned strata with widespread bedding-parallel slip indicative of
folding by flexural slip, whereas the syn-folding strata above define a
200 m amplitude fold. In the inner and outer sectors of the forelimb, both
pre- and syn-folding strata are near vertical to overturned and the
unconformity angle ranges from 10 to 30°. In the
central portion of the forelimb, syn-folding layers are gently dipping,
whereas the angular unconformity is about 90° and the unconformity
surface displays strong S–C shear structures, which provide a top-to-foreland slip sense. This sheared unconformity is offset by steeply dipping
faults, which are at low angles to the underlying layers of the pre-folding
unit. Strong shearing along the unconformity surface also occurred in the
inner sector of the forelimb, with S–C structures providing an opposite,
top-to-hinterland slip sense. Cross-cutting relationships and slip
senses along the pre-folding bedding surfaces and the unconformity indicate
that regardless of its orientation, layering in the pre- and syn-folding
sequences of the Sant Corneli-Bóixols anticline were continuously
slipped. This slipping promoted an intense stress deflection, with the
maximum component of the stress tensor remaining at low angles to bedding
during most of the folding process.
Jose Manuel Gil-Márquez, Matías Mudarra, Bartolomé Andreo
et al.
The Salinas-Los Hoyos karst system is a geological diapiric structure formed by materials of diverse nature (clays, sandstones, evaporites, volcanic rocks, dolostones, etc.) placed between Malaga and Granada provinces (S Spain). The abundance of evaporite rocks (gypsum, anhydrite and halite) and their high solubility contribute to the development of exokarstic features (dolines, uvalas, sinkholes). Grande and Chica lakes are dolines located in the western border of the diapir that are intersected by the piezometric level. Close to the first wetland is the Aguileras spring, which is the main discharge point of the west sector of the system. To assess the wetland-spring relation and the general functioning of the system, the geomorphologic framework has been analyzed and hydrogeological controls have been performed, consisting in limnimetric and discharge logging and in situ measurements of physico-chemical parameters (EC and water temperature). Furthermore, spring, wetland and rain water samples have been taken for subsequent chemical and isotopic analysis. Preliminary results show that wetland water level and spring discharge follow a similar trend, consistently with the inertia of the system. However, their hydrochemical evolution and isotopic values differ, thus wetland groundwater interaction has not been fully determined. Nevertheless, present research suggests that the hydrogeological connection would be more likely during wet periods, when the water table is at higher altitude.
Key words: Evaporitic (karst) aquifer, Hydrological and hydrogeological behaviours, Natural responses, South Spain, Wetlands.
When scientists apply Archie's first law they often include an extra
parameter <i>a</i>, which was introduced about 10 years after the equation's first
publication by Winsauer et al. (1952), and which is sometimes called
the “tortuosity” or “lithology” parameter. This parameter is not,
however, theoretically justified. Paradoxically, the Winsauer et
al. (1952) form of Archie's law often performs better than the
original, more theoretically correct version. The difference in the
cementation exponent calculated from these two forms of Archie's law is
important, and can lead to a misestimation of reserves by at least 20 %
for typical reservoir parameter values. We have examined the apparent
paradox, and conclude that while the theoretical form of the law is correct,
the data that we have been analysing with Archie's law have been in error.
There are at least three types of systematic error that are present in most
measurements: (i) a porosity error, (ii) a pore fluid salinity error, and
(iii) a temperature error. Each of these systematic errors is sufficient to
ensure that a non-unity value of the parameter <i>a</i> is required in order to
fit the electrical data well. Fortunately, the inclusion of this parameter in
the fit has compensated for the presence of the systematic errors in the
electrical and porosity data, leading to a value of cementation exponent that
is correct. The exceptions are those cementation exponents that have been
calculated for individual core plugs. We make a number of recommendations for
reducing the systematic errors that contribute to the problem and suggest
that the value of the parameter <i>a</i> may now be used as an indication of data
quality.
The remediation of contaminated sites has been faced in Italy and elsewhere in the world with a series of works originated by the availability of specific technologies for the recovery of soils and groundwater quality, acting in accordance with the principle of sustainability. A framework of rules (target values and type of intervention) and a summary of the quality of soil and groundwater in Italian contaminated sites must be mentioned first. The design of the remediation was also permitted by the improvement of the site characterization, with specific equipments addressed for example to identify the stratigraphy of the contaminants, the presence of volatile compounds, the sampling of water of significant groundwater quality, etc.. The text describes some interventions relating to physical and hydraulic barriers that involve substantial capital and O&M costs and also the consumption of natural resources. Subsequently they are also considered important in situ interventions that resulted in a reduction in the concentration and significant recovery of the pollutants mass. The evolution of the residual concentration in the groundwater must be considered by monitoring natural attenuation. Despite the recovery of the mass of pollutants even up to 90-99%, values of cleanup (expected concentrations of the order of μg/L) which are established by national legislation have not been achieved. It can be stated that the scientific community is considering the new paradigm expressed by the “order of magnitude of the flow of pollutant mass” to replace the old paradigm consisting in the “limit value of final concentrations”.
Navid Navidi Izad, Fereshteh Sajjadi, Afsaneh Dehbozorgi
et al.
Abstract
Palaeonvironment of the Dalichai Formation, northeastern Semnan, is envisaged based on 69 samples studied palynologically. Diverse and well-preserved palynofloras, viz., miospores, dinoflagellate cysts, foraminiferal test linings, acritarchs, wood debris (plant tissue) and Amorphous Organic Matters (AOM) occur in the material examined. The presence of relatively abundant proximate dinoflagellates and ±laevigate acritarchs in the lower part of the section studied implies sedimentation in a turbulent shallow environment. However, occurrence in the upper part of the section of abundant chorate dinoflagellates as well as notable proportion of blade-shaped to equal dimensional opaque palynomacerals seem to signify marine incursion and accumulation in an open marine setting. In most of the samples examined, prevalence of transparent AOM denotes a low oxygenated environment and slow rate of accumulation. Moreover, incidence of three palynofacies types (II, IV, VI) in the pertinent material also corroborates a shallow low oxygenated environment with low sedimentation rate which gradually deepened upward in the section.