Detrital apatite Lu-Hf and U-Pb geochronology applied to the southwestern Siberian margin

First published: 03 February 2022Apatite is increasingly used in sedimentary provenance studies. However, detrital apatite U–Pb geochronology can be challenging due to the presence of non-radiogenic Pb, its intermediate closure temperature (~350–550°C) and/or age-resetting by metamorphic/metasomatic processes. The Lu–Hf system in apatite has a higher closure temperature (~675–750°C) and is, therefore, more robust to thermal resetting. Here we present the first detrital apatite Lu–Hf age spectra. We have developed a laserablation Lu–Hf dating technique, using reaction-cell mass spectrometry, that allows rapid cost-effective analysis, required for detrital apatite studies. The method is best suited to Precambrian detritus, permitting greater radiogenic Hf ingrowth. Using samples from Siberia, we demonstrate: (1) excellent correlations between U–Pb and Lu– Hf dates for apatites from igneous protoliths; and (2) that Lu–Hf dating can detect primary age information in metamorphic grains. Hence, when used in tandem with U–Pb zircon and apatite geochronology, Lu–Hf apatite dating provides a powerful new tool for provenance studies.Stijn Glorie, Jack Gillespie, Alexander Simpson, Sarah Gilbert, Andrei Khudoley, Nadezhda Priyatkina, Martin Hand, Christopher L. Kirklan

Petrogenesis and tectonic setting of the mafic-ultramafic rock association from NW Senja, West Troms Basement Complex

The studied mafic-ultramafic rock association occurs within Archean tonalitic gneisses and metasupracrustal suites of the Astridal belt belonging to the West Troms Basement Complex in the northwestern part of the Senja Island. The rock association appears in lens-shaped bodies, up to 200 m long, which are oriented conformal to the major metamorphic fabric of the host rock. The rock association is made up by interlayered units of green spinel-bearing olivine orthopyroxene-hornblendite, hornblende peridotite, olivine hornblendite, hornblendite and amphibolite (metagabbroic rock). Microscope studies and whole rock geochemical data indicate that the ultramafic rocks represent a single magmatic series of mafic and ultramafic olivine-amphibole cumulates, which have been significantly affected by metamorphism. Igneous mineral and whole rock trace element data indicate MORB affinity of the cumulates and suggest their emplacement in oceanic rift or rifted continental margin setting. The studied cumulates may represent a crustal remnant of the Paleoproterozic Svecofennian ocean. The rocks were metamorphosed together with the supracrustal suites of the Astridal belt during the major Svecofennian event about 1.74 Ga ago as indicated by a U-Pb age of metamorphic zircons from the metagabbroic rock belonging to the studied suite

Data for: A preliminary reassessment of the Siberian cratonic basement with new U-Pb-Hf detrital zircon data

Supplemetary file 1 (Priyatkina et al). New Hf in zircon analysis of detrital zircons from Precambrian sedimentary rocks of Siberi

Data for: A preliminary reassessment of the Siberian cratonic basement with new U-Pb-Hf detrital zircon data

Supplemetary file 1 (Priyatkina et al). New Hf in zircon analysis of detrital zircons from Precambrian sedimentary rocks of SiberiaTHIS DATASET IS ARCHIVED AT DANS/EASY, BUT NOT ACCESSIBLE HERE. TO VIEW A LIST OF FILES AND ACCESS THE FILES IN THIS DATASET CLICK ON THE DOI-LINK ABOV

A preliminary reassessment of the Siberian cratonic basement with new U-Pb-Hf detrital zircon data

New and compiled U-Pb-Hf detrital zircon data from provincial Meso- to Neoproterozoic sedimentary basins characterize the buried crust of the Siberian cratonic basement. Along the northwestern Siberian cratonic margin (Turukhansk uplift, Yenisei Ridge) the basins accumulated predominantly 2.6–2.5 Ga zircons with εHf (T) values of +3 to −7, and 1.9–1.85 Ga zircons, characterized by εHf (T) values of −10 to +10. In the southwestern part of the craton (Prisayan uplift), similar 1.9–1.85 Ga and older Archean zircons are common, whereas in the eastern part older Paleoproterozoic zircons of 2.15–1.95 Ga with minimum εHf (T) values of −25 are widespread. The unique detrital age spectra for various parts of the craton provide a basis for unravelling the age of buried domains of the Siberian craton. A correlation of isotopic records from different domains, combined with geological evidence, may suggest that the craton consists of (1) the Archean unit, younging toward the present N-W direction and (2) three N-S-trending Paleoproterozoic collisional belts, extending along its western (the Angara belt) and eastern (the Hapschan belt) margins, and in the middle of the craton (the Magan belt). The proposed structural and isotopic domains of the Siberian craton compare well with those of northern Laurentia, providing a new evidence for the two cratons were connected within the Nuna supercontinent

The Neoproterozoic evolution of the western Siberian Craton margin: U-Pb-Hf isotopic records of detrital zircons from the Yenisey Ridge and the Prisayan Uplift

We present new LA ICP-MS U-Pb-Hf detrital zircon data from Neoproterozoic sedimentary basins located along the south-western margin of the Siberian Craton. In the Yenisey Ridge (the Taseeva basin), siliciclastic sedimentary units contain abundant 2.7–2.5 Ga, 2.0–1.75 Ga and 0.95–0.57 Ga detrital zircon populations, whereas for the Prisayan Uplift slightly different detrital zircon ages of 3.0–2.5 Ga, 2.2–1.8 Ga and 0.95–0.65 Ma are common. Mid Neoproterozoic sandstones were deposited in a rift setting or along a rifted cratonic margin facing a back-arc basin, whereas the immature to submature upper Ediacaran to Lower Cambrian fluvial successions were probably deposited in the foredeep setting, at the expense of proximal Neoproterozoic igneous suites and the underlying metasedimentary basement. A range of εHf values from −10 to +14 indicates intense mixing between juvenile and evolved magma components in a continental arc setting at ca. 950–570 Ma. Geological evidence, persistent input of detrital zircon material derived from ancient crustal units of western Siberian cratonic margin and evolution of Hf isotopic compositions suggest that the Neoproterozoic arc system of the Yenisey Ridge and, partly, Sayan orogens developed along the active margin of Siberia. In the Neoproterozoic, the arc system probably extended along the periphery of Rodinia into the Taimyr orogen of northern Siberia and Valhalla orogen of north-eastern Laurentia

Higher Pedagogical Education for Students with Disabilities: an Accessible Environment of Professionalization

The article deals with the problem of professional pedagogical preparation of students with disabilities. The basis for the implementation of the educational standard for students with disabilities is the individualization of learning. Psychological support of educational process for people with disabilities involves psycho-diagnostics, individualized psycho-correction, a variety of training, psychological counseling.В статье рассматривается проблема профессиональной педагогической подготовки студентов, имеющих ограничения в состоянии здоровья. Основой реализации ФГОС для студентов с ОВЗ выступает индивидуализация обучения на основе адаптированных программ дисциплин. Психологическая поддержка образовательного процесса для лиц с ОВЗ предполагает психодиагностику, индивидуализированную психокоррекцию, разнообразные тренинги, психологическое консультирование