Transitional Series Research Articles

Mapping coastal wetland changes from 1985 to 2022 in the US Atlantic and Gulf Coasts using Landsat time series and national wetland inventories

The areal extent of coastal wetlands is declining rapidly worldwide, and scientists and land managers need land cover maps that show the magnitude and severity of changes over time to assess impacts and develop effective conservation strategies. Within the United States (US), widely-used, continental-scale wetland land cover data products are either static in time (The National Wetlands Inventory) or have a course temporal resolution and do not distinguish between different types of change (the NOAA Coastal Change Analysis Program, C-CAP). This study presents a new coastal wetland geospatial data product that leverages the Landsat database and maps annual land cover across the US Atlantic and Gulf Coasts from 1985 to 2022. The algorithm was trained on the existing US wetland inventories to make the final maps compatible with products that are used in operational management. A multi-stage classification approach was designed that uses the Continuous Change Detection and Classification (CCDC) algorithm to characterize time series of remote sensing reflectance with fitted harmonic functions and identify when changes likely occurred. The fitted time series models are then input into a random forest classifier to make a class prediction. An annual-scale random forest classification is performed in parallel, and results from both algorithms are combined and analysed to detect both gradual and abrupt changes and to identify transitional time series segments. A time series smoothing procedure is subsequently applied to ensure class transitions are logical and consistent and extract a summative change characterization map that shows the severity and spatial density of change. The final maps distinguish between four homogenous classes and six mixed classes, representing areas that are transitioning between classes and where the boundaries between classes are unstable. The algorithm uses data and tools within the Google Earth Engine platform, making it accessible and scalable. The average overall accuracy is 93.7%, and the average class omission and commission errors are 6.7% and 6.4%, respectively. A variety of change detection comparisons were performed, using the existing wetland inventory that employed a fundamentally different change detection approach, and a more comparable annual-scale, Landsatderived product that estimated changes across the Northeastern Atlantic Coast. These comparisons show that the new products’ severe change magnitude matches that of the existing US inventory and the moderate change magnitude matches that of the Northeastern Coast product. The 2019 Wetland Status and Trends Report estimated that net loss rates in emergent wetlands from 2010 to 2019 amount to 1.7%, and the new maps show an equivalent loss rate of 1.6%, again showing close agreement.

Snapshots of Coastal Ecology Using Multiproxy Analysis Reveals Insights Into the Preservation of Swamp and Marsh Environments Since the Late Pleistocene

AbstractThe southeastern United States Coastal Plain ecosystem contains baldcypress (Taxodium distichum) swamps and grass‐dominated marshes. These ecosystems also occurred on the exposed continental shelf during lower sea levels but are rarely preserved due to the mechanically erosive nature of transgression and regression. Two presently marine sites on the northeastern Gulf of Mexico's continental shelf contain well‐preserved woody terrestrial sediments that were the subject of previous studies. This study continues the investigation using geochemical (δ13C, δ15N, δ34S) and palynological characteristics of these formerly terrestrial sediments to determine if swamps and/or marshes existed at the time of deposition. The first site is located ∼20 km southeast of Horn Island, Mississippi (MS) and the core has terrestrial sediments radiocarbon dated to 11,066–10,228 (2σ) calibrated years BP (early Holocene). The second site is the “Alabama Underwater Forest” located ∼13 km south of Gulf Shores, Alabama (AL) and the cores have terrestrial sediments optically stimulated luminescence dated to 63 ka (±10 ka, 2σ) to 72 ka (±16 ka, 2σ) (late Pleistocene). Geochemical results for the MS sediments indicate a swamp‐to‐freshwater marsh transitional series, whereas the AL sediments indicate a swamp‐to‐saltwater marsh transitional series, both supported by palynological results. Further exploration of the geochemical results using linear discriminant analysis, trained with published geochemical data, supports the swamp and marsh interpretations. We conclude that the near‐pristine preservation of these woody deposits is not solely due to physical mechanisms, such as rapid burial, but is also coupled with anoxia‐ and euxinia‐driven biogeochemical reactions promoting wood and woody debris preservation in swamp and marsh environments.

Electronic Structure and Ligand Effects on the Activation and Cleavage of N2 on a Molybdenum Center.

Dinitrogen fixation under ambient conditions remains a challenge in the field of catalytic chemistry due to the inertness of N2. Nitrogenases and heterogeneous solid catalysts have displayed remarkable performance in the catalytic conversion of dinitrogen to ammonia. By introduction of molybdenum centers in molecular complexes, one of the most azophilic metals of the transitional metal series, moderate ammonia yields have been attained. Here, we present a combined multiconfigurational/density functional theory study that addresses how ligand fields of different strengths affect the binding and activation of dinitrogen on molybdenum atoms. First, we explored with MRCI computations the diatomic Mo-N and triatomic Mo-N2 molecular systems. Then, we performed a systematic examination on the stabilization effects introduced by external NH3 ligands, before we explore model neutral and charged complexes with different types of ligands (H2O, NH3, and PH3) and their consequences on the N2 binding and activation.

Petrogenesis and geochemical evidence from early Jurassic intrusive rocks and their implications for subduction of the Paleo-Pacific Plate in the Yanbian area, Northeast China

Subduction of the Paleo-Pacific Plate plays a key role in the Early Jurassic magmatism evolution in the Yanbian area, Northeast China. In this paper, zircon U–Pb ages, whole-rock geochemical, and Sr–Nd–Hf isotopic compositions are presented. The Early Jurassic gabbros, diorite enclaves, granodiorites, and granites ages range from 183 to 189 Ma. They are characterized by enrichment in large-ion lithophile elements and depletion in high-field strength elements. The gabbros are classified as low- and medium-K tholeiitic, granodiorites and granites are high-K calc-alkaline I-type, and diorite enclaves are calc-alkaline transitional series. The gabbros have zircon εHf(t) values of 6.81–9.89, whole-rock 87Sr/86Sr(i) = 0.7043–0.7044, and εNd(t) from 2.72 to 2.80. The diorite enclaves have zircons with εHf(t) values of 8.26–12.80, whole-rock 87Sr/86Sr(i) = 0.7051, and εNd(t) from 0.96 to 1.09. The granodiorites and granites have zircon εHf(t) values of 7.59–12.87, whole-rock 87Sr/86Sr(i) = 0.7042–0.7066, and εNd(t) from 2.33 to 2.61. These data indicate that gabbroic magmas were derived from partial melting of a depleted mantle wedge metasomatized by subduction-related fluids. The basaltic magma underplated and heated the juvenile crust, whereas the granodiorites and granites might be the product of fractional crystallization of a mixture of basaltic and felsic magmas or derived from partial melting of the juvenile lower crust. Our data constrain the petrogenesis of these Early Jurassic intrusive rocks which are attributed to subduction of the Paleo-Pacific Plate beneath Eurasia continent in northeastern China.

Abrolhos Magmatic Province petrogenesis and its link with the Vitória-Trindade Ridge, Southeast Brazilian Margin, South Atlantic Ocean

The Abrolhos Magmatic Province (AMP) is an example of an igneous province with about 63,000 km2 located at the Continent-Ocean Boundary (COB), into the Southeast Brazilian Margin. The AMP emerges as five small islands (Santa Bárbara, Redonda, Siriba, Sueste, and Guarita) which integrate the Abrolhos Archipelago located about 55 km offshore Brazil. The studied rocks belong to a transitional basalt series of alkaline affinity, with evolved rocks with high TiO2 contents. This work presents new detailed fieldwork mapping, petrographic, and whole-rock chemistry data, besides Sr–Nd isotopic compositions from AMP rocks. Mapped magmatic rocks in the Abrolhos Islands have been described as extrusive rocks, but we point out that they are shallow intrusions, mostly sills, and should be grouped into diabase units based on fieldwork and textural features. The AMP lithogeochemical and isotopic data suggest the operation of differentiation processes more complex than simple fractional crystallization or AFC. Our model mixing calculations based on new and compiled Sr-Nd-Pb isotopic data suggest a mixture with a prevailing depleted asthenosphere mantle source (represented by DMM; ca. 80%) metasomatized by an enriched mantle I (EMI) component (≤ 10%) and a possible HIMU-type constituent (up to 10%) in the AMP genesis. The assimilation of subducted slabs of the oceanic crust associated with the HIMU signatures is possibly linked to the Brasiliano Event due to the range of the AMP Nd TDM model ages, from 407 to 767 Ma. A viable mechanism for the EMI end-member contribution could either be a physical detachment of the South American subcontinental lithospheric mantle during the breakup of the Gondwana or lithospheric delamination of the South American plate caused by an edge-driven convection mechanism. The AMP and the Vitória-Trindade Ridge (VTR) show an eastward decreasing age pattern from the older ca. 60 Ma Abrolhos Province to the younger Martin Vaz and Trindade Islands (ca. 4 – 0.1 Ma), located ca. 1200 km away from the Brazilian coastline. The volcanic alignment between the VTR and AMP, along with the overlap of geochemical and isotopic data of their different igneous rocks, cannot be a random feature but instead represent the sampling of similar shallow mantle reservoirs, thus suggesting a cogenetic relationship. Finally, a possible petrogenetic link between the AMP and VTR magmatism is discussed.

Karagaikul gold-porhyric ore occurrence (South Urals): geochemistry and petrogenesis of intrusive rock, composition of minerals of near-ore metasomatites and ores

The petrological and geochemical characteristics of intrusive rocks, sources of magmatic melts, as well as the composition of minerals of near-ore metasomatites and ores of the Karagaikul gold-porphyry ore occurrence located in the Main Ural fault zone in the South Urals have been studied. The content of petrogenic oxides was determined by the silicate method, rare elements – using ICP-MS analysis on a quadrupole mass spectrometer ELAH 9000. The composition of minerals was studied using electron microscopic analysis on a scanning electron microscope REMMA-202M. It was found that gabbro, gabbro-diorite and diorite of the ore-bearing dyke series of the Karagaikul ore occurrence are suprasubduction magmatites of normal alkalinity belonging to the transitional and calc-alkaline petrogenetic series. They were formed from fluid-saturated melts. The main source of melts for intrusive rocks was most likely spinel peridotites of the suprasubduction lithospheric mantle, previously metasomatized by aquatic fluids that arose during the dehydration of rocks of the subducting oceanic plate. The dykes underwent propylitization of the biotite-actinolite facies in a near-ore halo (paragenesis: biotite + actinolite + epidote + orthoclase + albite + quartz + chlorite + pumpelliite), and the host serpentinized ultrabasites – carbonatization (chromogenesis: dolomite + magnesite). According to the chlorite geothermometer, the temperature of propylite formation is 287–317 °С. Sulfide minerals in gold-bearing stockworks are represented by pyrite, chalcopyrite, galena, pentlandite, pyrrhotine, and violarite.

The latest Neoproterozoic basaltic and siliciclastic rocks and tectonic implications in the Tarim Craton, NW China

The Tarim Craton records protracted late Neoproterozoic rifting that overlaps with the breakup of Rodinia and assembly of Gondwana. However, the timing and interactions of these two tectonic processes remain contested. To constrain the tectonic significance of this prolonged rifting event, we present LA-ICP-MS zircon U–Pb ages and geochemical data from mafic and (meta)sedimentary rocks at the top of the craton’s Ediacaran succession. Two basalt samples from the northwestern Tarim Craton contain inherited zircon grains with a wide range of U–Pb ages, the youngest at ca. 620 ± 11 providing a maximum age for the magmatism. The youngest detrital zircon U–Pb ages from the southwestern and northern Tarim Craton are ca. 607 Ma and 617 Ma, respectively. Integrated with compiled magmatic and detrital zircon U–Pb ages, our study suggests that an episode of latest Neoproterozoic (ca. 620–600 Ma) magmatism occurred throughout the Tarim Craton. The Ediacaran mafic rocks form a transitional eruptive series between alkali and tholeiitic basalts derived from lithospheric mantle with slight crustal contamination and formed in an intra-continental rifting environment through mantle reactivation during post-subduction extension. Positioned at the outer margin of Rodinia, it is considered unlikely that the magmatism records prolonged plume-related breakup. Instead, it is thought to reflect rifting of an active continental margin in a fashion analogous to many of the peri-Gondwanan terranes, possibly related to the subduction mechanism of supercontinental breakup.

Petrogenesis, Magma Source, and Geodynamics of Paleogene Mafic Rocks, Huimin Sag, Jiyang Depression, Eastern China

A suite of Paleogene mafic rocks was collected from boreholes in the Huimin Sag of the Jiyang Depression with the aim of investigating the petrogenesis and nature of mantle source for these rocks and further providing insights into the characteristic of related mantle plume. Whole-rock geochemical data indicate that the mafic rocks have relatively lower SiO2 (42.93%–48.57%) contents and similar characteristics to alkaline basalt and belong to transitional calc-alkaline series. These samples were clearly enriched in LREEs and depleted in HREEs and were also characterized by the enrichment of LILEs, incompatible elements, and HFSEs, similar to those of the Ocean Island Basalt (OIB). In addition, they exhibited Pb enrichment; Y, Pr, and Yb depletion; absence of Nb-Ta anomalies; high Hf and low Zr; and Rb/Yb ratios exceeding 1.0, indicating characteristics of intraplate rift-type alkaline basalt. The samples exhibited (Th/Ta)PM and (La/Nb)PM ratios less than 1 and plotted within the OIB, EMI, and EMII fields, indicating that crustal components had no role in the generation of the rocks. With the exception of individual samples that have a distinctive range of ε Nd values, the majority of samples have complex ε Nd values of -1.15 to 5.56, indicating a mixture of different sources, which was also apparent in the δ18O-87Sr/86Sr diagram, in which the samples plot close to the downward nonlinear curve. Based on the isotopic and trace elemental analyses, these igneous rocks are intraplate rift-type alkaline basalt and are of mantle plume origin. The variations in 87Sr/86Sr, 143Nd/144Nd, ε Nd values, LREEs, and HFSEs were probably due to the different locations of the mantle plume for different samples. The primary magma of the rocks likely originated from the melting of a mantle plume and the further metasomatism of lithospheric mantle, continental, or oceanic crust.

Transitions as a Series of Sequences: Implications in Testing for and Diagnosing Autism

ABSTRACT Children who receive a diagnosis of autism spectrum disorder (ASD) are said to have characteristic difficulty with transitions. However, testing that informs ASD diagnosis overlooks children’s conduct during transitions between subtasks of the test. In this article, we describe and analyze the sequential organization of such transitions. First, we show that transitions come as an organized series of sequences, which we call the Transitional Activity Series (TAS). We then show how the TAS is a contingent accomplishment with a structure that clinician and child adapt to emergent troubles in co-orientation. Lastly, we analyze how a particular child’s “rigid and repetitive behaviors,” a criterion of ASD diagnosis linked to transitional difficulty, may work to facilitate, rather than upend, transitions between discrete testing tasks. Data in American English.

Age and Geochemistry of Late Jurassic Mafic Volcanic Rocks in the Northwestern Erguna Block, Northeast China

The northwestern Erguna Block, where a wide range of volcanic rocks are present, provides one of the foremost locations to investigate Mesozoic Paleo-Pacific and Mongol-Okhotsk subduction. The identification and study of Late Jurassic mafic volcanic rocks in the Badaguan area of northwestern Erguna is of particular significance for the investigation of volcanic magma sources and their compositional evolution. Detailed petrological, geochemical, and zircon U-Pb dating suggests that the Late Jurassic mafic volcanic rocks formed at 157–161 Ma. Furthermore, the geochemical signatures of these mafic volcanic rocks indicate that they are calc-alkaline or transitional series with weak peraluminous characteristics. The rocks have a strong MgO, Al2O3, and total alkali content, and a SiO2 content of 53.55–63.68 wt %; they are enriched in Rb, Th, U, K, and light rare-earth elements (LREE), and depleted in high-field-strength elements (HFSE), similar to igneous rocks in subduction zones. These characteristics indicate that the Late Jurassic mafic volcanic rocks in the Badaguan area may be derived from the partial melting of the lithospheric mantle as it was metasomatized by subduction-related fluid and the possible incorporation of some subducting sediments. Subsequently, the fractional crystallization of Fe and Ti oxides occurred during magmatic evolution. Combined with the regional geological data, it is inferred that the studied mafic volcanic rocks were formed by lithospheric extension after the closure of the Mongol-Okhotsk Ocean.

Geochemistry and geochronology of intermediate volcanic rocks from the Compostela area, Nayarit, Mexico: Implications for petrogenesis and tectonic setting

The Compostela area is located in the western Trans‐Mexican Volcanic Belt, which consists of volcanic rocks that produced during the Pliocene to Recent volcanism. In this paper, we present petrography, whole‐rock major‐ and trace‐element concentrations, Ar–Ar ages, and Sr–Nd isotopic data of volcanic rocks from the Compostela area in the south of the city of Tepic, Nayarit, Mexico. These volcanic rocks are of intermediate composition and belong to the transitional series: basaltic trachyandesites [52.72–53.94 wt% SiO2; 0.69–2.53 wt% MgO] and subalkaline series: low‐Si [55.11–60.94 wt% SiO2; 0.79–2.74 wt% MgO] and high‐Si [61.60–62.71 wt% SiO2; 0.36–0.80 wt% MgO] andesites. The 40Ar/39Ar dating of two basaltic trachyandesites yields plateau ages of 1.05 ± 0.15 Ma and 1.07 ± 0.17 Ma and the andesites yielded a plateau age of 2.42 ± 0.36 Ma. These results indicate that the studied rocks were formed during the Pleistocene in two discrete episodes. The basaltic trachyandesites show enriched light rare earth elements patterns relative to high rare earth elements [(La/Yb)N = 5.81–8.07] with negligible Eu anomalies. The andesites display enriched large‐ion lithophile elements (Ba, K) with anomalies of Nb (Th/Ce) and Ti in the three groups identified in the subalkaline series. The basaltic trachyandesites appear in a tight cluster of initial 87Sr/86Sr ratios (0.703519–0.703882) as compared to the basaltic andesite 87Sr/86Sr (0.704073) and positive ɛNd(t) values of +5.6 to +3.4, respectively, indicating that the basaltic trachyandesites were derived from intermediate magmas from a shallow mantle source. Geochemical modelling reveals that both basaltic trachyandesite and andesite rocks were derived by a process of crystal fractionation accompanied by assimilation of crustal rocks at the lower or middle level. Geochemical ratios and multidimensional discrimination diagrams, combined with the cross‐section of the subduction zone indicates that basaltic trachyandesites were generated from a rift and/or Ocean Island Basalt‐type source, whereas andesites were generated from a slab‐derived source in a subduction environment.

Cadosinopsis rehakovii sp. nov., a new calcareous dinocyst from the Jurassic-Cretaceous transitional interval of the Western Tethys.

Variegated limestones, a transitional series between red, Upper Jurassic radiolarite and whitish, Lower Cretaceous Maiolica limestone in the Pieniny Klippen Belt deposits in the Polish part of the Western Carpathians, have yielded rich microfossil assemblages with common calcareous dinoflagellate resting stages, hereafter, dinocysts. We found an undescribed dinocyst species in red-greenish limestone of a deep water, pelagic habitat in the Branisko succession of the Pieniny Klippen Basin and named it Cadosinopsis rehakovii sp. nov. The new species has a spherical to oval calcareous test ranging from 34 to 59 μm in length and 30 to 50 μm in width, with two layered wall. The inner layer is built of coarse–thick, plate-shaped calcite crystals and is white in transmitted light. The outer layer is built of fibrous crystals, vitreous (transparent) in transmitted light. The aperture is wide and seen only in the inner layer. We compared the detailed morphological characteristics of the new species with another species from the same genus in the Jurassic and Cretaceous Tethyan deposits. Specimens have been measured, grouped and interpreted using cluster analysis, principal component analysis (PCA) and canonical variate analysis (CVA). Among them, the new species shows a resemblance in cross-section to other species of Cadosinopsis, C. nowaki Borza, 1984, and C. andrusovi Scheibner 1967, previously described in literature. However, the two species are easily distinguishable by some features. Cadosinopsis. nowaki is bigger in size (length from 50 to76 μm and width from 43 to 67 μm), its inner layer is thicker and consists of vitreous-sparite calcite, and it has less centrically located chamber. C. andrusovi is much bigger in size as its length ranges from 68 to 108 μm and width ranges from 60 to 80 μm, and the cyst is more oval and its chamber less spherical. The new species is the third Cadosinopsis species described in the Tethyan realm and about two hundred and sixty-first fossil species (morphotype) described in the world so far.

Mantle source evolution beneath the Cameroon volcanic line: geochemical and geochronological evidences from Fotouni volcanic series, Western Cameroon

We present the first K-Ar geochronological and geochemical data (major and trace elements, as well as Sr, Nd, Pb, and Hf isotopes) on volcanic rocks from the Fotouni lavas in the central part of the Cameroon volcanic line (CVL). Two distinct compositional groups can be discriminated: alkaline and transitional lavas. The alkaline series ranges in composition from basanite and basalt to hawaiite and formed 14 to 3 Ma ago while the transitional series ranges from basalt and trachybasalt to basaltic trachyandesite and formed 47 to 38 Ma ago. All samples display trace element patterns dominated by light rare-earth element enrichments compared to heavy rare-earth elements. The alkaline samples have (87Sr/86Sr)i ranging from 0.70292 to 0.70340, eNd = 3.45 to 5.98, ɛHf = 1.95 to 5.63, and relatively radiogenic Pb isotopic compositions: 206Pb/204Pb = 19.891–20.592; 207Pb/204Pb = 15.639–15.693; 208Pb/204Pb = 39.566–40.044. Transitional basalts are characterized by relatively radiogenic Sr and unradiogenic Nd, Hf, and Pb: (ɛNd)i = − 10.82 to + 3.43; ɛHf = − 14.00 to + 3.13; 206Pb/204Pb = 18.0716 to 18.9274; 207Pb/204Pb = 15.532 to15.704; 208Pb/204Pb = 37.8141 to 39.4735. Several geochemical characteristics indicate that the transitional lavas have interacted with the continental crust while alkaline lavas did not suffer significant amounts crustal contamination. Both transitional and alkaline lava series can be explained by mixing between two mantle components: an enriched component and a HIMU-like component. These two mantle sources are probably located within the lithospheric mantle and are different from both the Saint Helena and the Mont Cameroon mantle.

Tectonics, Dynamics, and Plio‐Pleistocene Magmatism in the Central Tyrrhenian Sea: Insights From the Submarine Transitional Basalts of the Ventotene Volcanic Ridge (Pontine Islands, Italy)

AbstractIn the Tyrrhenian back‐arc basin, the Ventotene Volcanic Ridge (VR) represents a NW‐SE‐oriented morphological high, located 25 km north of Ventotene Island in the Eastern Pontine Islands. It is considered part of an alignment of volcanic edifices developed in the central‐eastern Tyrrhenian Sea, from the western Pontine Islands (WPI) to the Campanian Volcanic Region. The samples dredged along the VR are basalts to trachybasalts belonging to the transitional (TR) rock‐series, with a 40Ar‐39Ar age of 2.760 ± 0.039 Ma. Petrological and geochronological data link the VR basalts to the TR peralkaline rhyolites cropping out at the WPI (∼1.6‐1.1 Ma); here, during a time span of ∼4.5‐1.0 Ma highly differentiated products of high‐potassium calc‐alkaline (HKCA, ∼4.5‐2.9 Ma) and K‐alkaline (KA, ∼1 Ma) series were also erupted. Notably, the parental melts of the three rock‐series were recognized in the continental slope close to the WPI (TR, HKCA) and eastward, namely in eastern Pontine Islands (KA), at the VR (TR), and in the Campanian Plain (HKCA). All the parental melts show typical orogenic geochemical signatures being originated from a similar heterogeneous suprasubduction mantle source, without the involvement of anorogenic sources. Tectonically, the faults bordering the VR, associated to the Pliocene E‐W directed rifting stage of the Tyrrhenian back‐arc basin were characterized by a more intense activity during the time span ∼5.0‐2.0 Ma (the emplacement time of HKCA and TR series), while KA products are related to a later stage of extension deformation (<∼2.0 Ma) when the extensional direction changed to NW‐SE and the VR fault activity decreased.

The NE-SW Trending Fotouni and Fangam Basalt Cones: Evidence of Tectonic Control on Their Emplacement

The Fotouni volcanic rocks outcrop within mylonitic corridor, in the southern domain of the continental part of Cameroon Line (CL). The NE-SW shape display by these volcanic rocks within the mylonitic corridor is an uncommon case along the CL. Field and petrographic data and spaces image analysis were performed in order to understand the NE-SW shape display by these rocks. Geochemical data display two distinct volcanic compositional groups: alkaline lavas and transitional lavas. Alkaline series ranges in composition from basanite, basalt to hawaiite and transitional series range from basalt, trachy-basalt to basaltic trachy-andesite.
 Field investigations show that the Fotouni, Fangam, Song and Mbeng basalts outcrops as NE-SW trending prismatic dykes which displaying well differentiated vertical tetragonal, pentagonal and hexagonal prisms within the Fotouni-Kékem shear zone (FFSZ). The overall NE-SW orientation of hills, where these prisms outcrop suggests the tectonic control on the emplacement of these rocks. Indeed, the activation of the FFSZ developed various fracture networks that facilitate magma uplift and the emplacement of the Fomopéa and Bandja plutons during the Pan-African orogeny. These Pan-African activations of the Fotouni fault weaken the crust during the Paleozoic. These weaken zones constitute path way for emplacement of volcanic dykes during the Tertiary within the NE-SW faults, probably facilitated by the general extension at the end of Cretaceous.

Magmatic affinities and evolution of Mount Telaga Rano, Mount Sahu and Mount Onu, North Maluku: analyses of phenocrysts chemical composition

Mount Talaga Rano, Mount Sahu and Mount Onu are volcanoes in Telaga Rano volcanic complex, North Maluku. Lava of Mount Telaga Rano showed andesitic composition with magmatic temperature of 920°C-1170°C, contains plagioclase (An36-85), enstatite, augite, pigeonite, magnetite, ulvospinel and olivine (Fo64-73) phenocrysts in the groundmass of microliths of plagioclase, volcanic glass, opaque minerals and pyroxene. Lava of Mount Sahu showed the andesitic and basaltic composition. The andesitic magma has temperature in the range between 946°C and 1007°C, whereas the basaltic magma has temperature in the range between 1192°C and 1330°C. The andesitic lava of Mount Sahu has plagioclase (An29-67), enstatite, augite, magnetite and ulvospinel phenocrysts in the groundmass of microliths of plagioclase, volcanic glass, opaque minerals and pyroxene, whereas the basaltic lava contains augite, pigeonite, plagioclase (An30-91), olivine (Fo56-77) and magnetite in the groundmass of microliths of plagioclase, volcanic glass pyroxene and opaque minerals. Moreover, lava of Mount Onu showed the andesite composition with magmatic temperature of 970°C-1090°C, contains plagioclase (An25-89), enstatite, a small amount of ferrosilite, augite, pigeonite, magnetite, ulvospinel and olivine (Fo51-72) phenocrysts in the groundmass of microliths of plagioclase, volcanic glass, opaque minerals and pyroxene. The chemical composition of olivine, pyroxene and plagioclase phenocrysts have been used to identify the magmatic affinities and evolution of those volcanoes. Clinopyroxene phenocrysts of the lavas show quadrilateral component variations which are characterized by low Cr, Al and Ti contents. The pyroxene data indicate that the magmas from those volcanoes have magmatic affinities with calc-alkaline to transitional series. Furthermore, we suspected that there was iron enrichment during the magma evolution. Based on the mineralogical identification of phenocrysts, magma evolution within each magma was controlled by fractional crystallization, associated with magma mixing. The more primitive magma injection greatly affected the composition of the magma and it could turn into more basaltic composition.

Lower-middle Darriwilian index conodonts from the Precordillera: new taxonomical approaches

A taxonomic review study on the apparatuses of the lower-middle Darriwilian index conodonts, based on the collections from the Precordillera and those described and illustrated in worldwide literature, had led to a new interpretation of the Lenodus apparatus composition. This apparatus is composed of pectiniform elements without mirror symmetry (Pa and Pb elements) with pastiniscaphate morphology and sometimes showing a micropattern structure (honeycomb) on the platform surface. The transitional series of S elements present the elements alate Sa, tertiopedate Sb, bipennate Sc, and quadriramate Sd with wartlike extensions on the tip of the cusps, and the M elements have a modified “geniculate” morphology. The analysis of the apparatuses of the Darriwilian index conodonts allows us to interpret that the genus Lenodus includes the following species: Lenodus variabilis, Lenodus crassus, Lenodus pseudoplanus, and Lenodus suecicus. This proposal is supported by the apparatus architecture, the transitional morphological features of the P elements, and the micropattern structure on the P and S elements present in all these species.

Индивидуальные различия в восприятии сходства изображений лиц и характеристики окуломоторной активности

The article presents the results of the cross-cultural study with participation of representatives of Russian and Tuva nationalities. Individual differences in subjective evaluation of magnitude of similarity of images forming a transitional series between Mongoloid and Caucasoid faces were revealed. The individual differences occurred mainly in relation to the target pairs in which one or both images were borderline in the transitional series, and which did not consist of images between which there was a large morphing step. These differences were associated with the features of oculomotor activity recorded with the help of an eye tracker during the perception of test images. The most significant differences in the duration and variance of visual fixations were found for two borderline images in the transitional series. Among Tuvan and Russian participants, the greatest individual differences in subjective similarity ratings were found for the same test pairs of facial images. In relation to these test pairs, general, opposite and specific for the Tuva and Russian samples trends were identified regarding indicators of oculomotor activity. The results indicate the constructivist nature of subjective assessment of similarity magnitude, and the connection of this process with characteristics of oculomotor activity.

Категоризация этнических лиц русскими и тувинцами в дискриминационных задачах

The opposite tendencies towards blurring the boundaries of compact living of ethnic groups and of relocation of large groups of strangers into the territories of compact residence of local groups generate a number of specific phenomena connected with the inter-group perception. We conducted a comparative study of perception and communication of transition series of “ethnic faces” among two small-scale isolated populations and representatives of the corresponding ethnic groups in multi-ethnic cities. The participants were to solve two discrimination task, one individually, the AB=X task, the other one, the dual “same-different” task, in dyads. For all samples of subjects, of In the AB=X task, the maximum discrimination efficiency was recorded for the same no. 2—3 pair of transition images series This may indicate that all subjects relied on the morphological features stimulus faces than on anything else. Also a tendency is observed toward similarity in the dynamics of efficiency of task performance in different groups of subjects, with the exception of the sample of Russians from the metropolis. At the same time, in the dyadic experiment, subjects from megacities demonstrate different trends in terms of the maximum efficiency of task performance. The sample of Russian subjects from Moscow demonstrates a significantly smaller decrease in efficiency when approaching the edges of the transitional series of stimulus images in the AB=X task, but not in the dual task. This is probably due to different nature of the tasks, i.e. one may easily suppose a more developed ability to perceptually discriminate between ethnic faces resulting from their greater variety in the environment, as in Moscow megacity, whereas it does not seem reasonable to suppose difference in communication skills required to perform the dual task across the samples.

Stages of Trap Magmatism in the Norilsk Area: New Data on the Structure and Geochemistry of the Volcanic Rocks

A periodic character of the evolution of trap magmatism was inferred by many researchers from the fact that sequences of volcanic rocks consist of alternating units of lava flows and tuff. A new phase of studying magmatic rocks in the Siberian Platform was related to the possibility of apply high-precision geochemical techniques in studying trace elements and Sr, Nd, and Pb isotopic compositions. The use of these techniques made it possible not only to identify small individual cycles in the vertical sections of volcanic rocks but also to distinguish larger stages. The currently most widely acknowledged scenario of the origin of volcanic rocks involves three stages, during which oceanic-island basalts (OIB), transitional series (intermediate between OIB and WPB), and within-plate basalts (WPB) were formed. This scenario was inferred mostly from data on rocks in the western part of the Norilsk area (Kharaelakh Trough). This publication presents recently obtained data on the inner structure of the sequences of volcanic rocks and the geochemistry of basalts in the eastern part of the territory, where no rocks show transitional characteristics have ever been found. They can be classified into two types that have clearly different composition and occur in different areas. These types characterize two major stages of the origin of volcanic rocks: rift-related and trap magmatism itself. The rocks produced during these stages occur at neighboring territories.