Sedimentary geology of the Middle Carboniferous of the Donbas region (Dniepr-Donets basin, Ukraine)

Peer reviewedPublisher PD

Geochronological constraints on the Paleozoic to Early Mesozoic geodynamic evolution of southern coastal Peru

The main objective of this dissertation was to establish a chronostratigraphic framework for the south Peruvian margin for the late Paleozoic to Mesozoic based on geochronological, geochemical and isotopic data on periods of magmatism and magmatic quiescence along the western Gondwana margin since the onset of subduction around 530 Ma ago. Our integrated geochronological study, revising the information of sedimentary basins and magmatism in southern coastal Peru (15-18°S) provide new insights in the evolution of this segment of the western Gondwana margin since the onset of subduction

A Hf-isotope perspective on continent formation in the south Peruvian Andes

Convergent continental margins are the primary host of both growth and loss of continental crust. Continental growth largely occurs via subduction-driven magmatism, whereas continental loss largely occurs via subduction erosion and sediment subduction. Because the latter typically involves partial recycling into magmas, both growth and loss of continental crust can be represented in the magmatic record. The degree of crustal recycling can be estimated from the initial Hf isotope signatures in both magmatic and detrital zircon grains. Recent insights into the geodynamic evolution of the Peruvian margin, in combination with a new dataset of Hf isotopic data on zircon from the Carboniferous to Early Cretaceous, enable us to (1) compare the geodynamic history of the southern Peruvian margin with its Hf isotopic evolution, and (2) quantify the crustal growth between 500 and 135 Ma. The data exhibit a correlation with trends in isotope composition v. time and reflect the dominantly extensional regime that prevailed from the onset of subduction from 530 Ma to c. 135 Ma. This study demonstrates that the Peruvian margin experienced continental growth with juvenile input to arc magmatism of 30–45% on average, and illustrates the use of U–Pb and Hf isotopes in zircon as a tool to trace episodes of crustal growth through time. Supplementary material: Hf istopic analyses on zircon (A1 and A2) and new U–Pb zircon ages (A3) are available at http://www.geolsoc.org.uk/SUP18661

New age constraints on the palaeoenvironmental evolution of the late Paleozoic back-arc basin along the western Gondwana margin of southern Peru

The tectonic evolution of the western Gondwana margin during Pangaea amalgation is recorded in variations in the Permo-Carboniferous back-arc basin sedimentation of Peru. This study provides the first radiometric age constraints on the volcanic and sedimentary sequences of south-central eastern Peru up to the western-most tip of Bolivia, and now permits the correlation of lateral facies variations to the late Paleozoic pre-Andean orogenic cycle. The two phases of Gondwanide magmatism and metamorphism at c. 315 Ma and c. 260 Ma are reflected in two major changes in this sedimentary environment. Our detrital U-Pb zircon ages demonstrate that the timing of Ambo Formation deposition corroborates the Late Mississipian age estimates. The transition from the Ambo to the Tarma Formation around the Middle Pennsylvanian Early Gondwanide Orogeny (c. 315 Ma) represents a relative deepening of the basin. Throughout the shallow marine deposits of the Tarma Formation evidence for contemporaneous volcanism becomes gradually more pronounced and culminates around 312 - 309 Ma. Continuous basin subsidence resulted in a buildup of platform carbonates of the Copacabana Formation. Our data highlights the presence of a previously unrecognized phase of deposition of mainly fluvial sandstones and localized volcanism (281-270 Ma), which we named Oqoruro Formation. This sedimentary succession was previously miss-assigned to the so-called Mitu Group, which has recently been dated to start deposition in the Middle Triassic (~245-240 Ma). The emersion of this marine basin coincides with the onset of a major plutonic pulse related to the Late Gondwanide Orogeny (c. 260). Exhumation lead to the consequent retreat of the epeiric sea to the present-day sub-Andean region, and the coeval accumulation of the fluvial Oqoruro Formation in south eastern Peru. These late Paleozoic palaeoenvironmental changes in the back-arc basins along the western Gondwana margin of southern reflect changes in tectonic plate reorganization in a long-lived Paleozoic accretionary orogeny

Southwestward tilting of the Ordos Loess Plateau, central China: topographic response to India-Asia convergence deduced from drainage systems

International audienceThe Ordos Loess Plateau with its iconic fluvial incision pattern represents an uplifted but internally stable plateau crustal block on the eastern fringe of the Tibetan Plateau. The Ordos Loess Plateau deeply incised river landscapes and hence its inaccessibility helped to protect ancient China from invading nomads from the north. The Ordos Block is internally free of seismicity but its boundaries feature severe high-magnitude earthquakes. Due to the ongoing India-Asia convergence, the northeastward expansion of the Tibetan Plateau leading to the eastward lateral extrusion of fault-bounded blocks. The Ordos Loess Plateau is part of one of these blocks and is still affected by lateral eastward motion along crustal scale faults and large surface uplift from Late Miocene to present. In this study, we investigated the effect of fault activity on the morphological evolution of the Ordos Loess Plateau. To quantify the effect of uplift gradients on the drainage systems, we investigated topographic patterns and landform metrics through field surveys and topographic analysis based on digital elevation models. Field surveys show that the southern boundary of the Ordos Loess Plateau to the Weihe Graben is still tectonically active (evidence for faulting in quaternary sediments). We found that the drainage is consistently directed towards the Weihe Graben in the southeast. Fluvial channels are in a state of morphological disequilibrium, with steep channel segments towards the Weihe Graben and meandering low gradient rivers in the central Ordos Loess Plateau. Over substantial portions, the shape of the longitudinal channel profile in the Ordos Loess Plateau is straight and deviates from usual graded longitudinal channel profiles. We further found that the degree of erosion and plateau incision is pronounced in the eastern part of the Ordos Loess Plateau, while the southwestern part is less incised. The drainage network indicated that the drainage basins are tilted toward the Liupanshan Mountains overthrust in the southwest. We conclude that the far-field influence of the Cenozoic uplift of the Tibetan Plateau activated the southwestern and southern boundary faults around the Ordos Loess Plateau. The drainage systems reorganized to a principal southern flow direction and thereby progressively incised in the Ordos Loess Plateau, causing severe soil erosion

A Hf-isotope perspective on continent formation in the south Peruvian Andes

<p>Convergent continental margins are the primary host of both growth and loss of continental crust. Continental growth largely occurs via subduction-driven magmatism, whereas continental loss largely occurs via subduction erosion and sediment subduction. Because the latter typically involves partial recycling into magmas, both growth and loss of continental crust can be represented in the magmatic record. The degree of crustal recycling can be estimated from the initial Hf isotope signatures in both magmatic and detrital zircon grains. Recent insights into the geodynamic evolution of the Peruvian margin, in combination with a new dataset of Hf isotopic data on zircon from the Carboniferous to Early Cretaceous, enable us to (1) compare the geodynamic history of the southern Peruvian margin with its Hf isotopic evolution, and (2) quantify the crustal growth between 500 and 135 Ma. The data exhibit a correlation with trends in isotope composition v. time and reflect the dominantly extensional regime that prevailed from the onset of subduction from 530 Ma to <em>c.</em> 135 Ma. This study demonstrates that the Peruvian margin experienced continental growth with juvenile input to arc magmatism of 30–45% on average, and illustrates the use of U–Pb and Hf isotopes in zircon as a tool to trace episodes of crustal growth through time. </p

Age and geodymamic setting of Jurassic arc volcanism in southern coastal Peru

The westem margin of the South American Plate is the Earth's longest lived active continental margin, and hence serves as the type locality for active margin orogenic processes. The Tertiary evolution of the margin has been studied in detail (Dewey and Lamb, 1992), whereas the Mesozoic and older history is still poorly constrained. Our study aims to reconstruct the late Triassic(?)- Jurassic evolution of the southern Peruvian margin and to constrain the age, chemistry, and palaeogeographic setting of volcanic-sedimentary arc sequences in the Arequipa Terrane. The Triassic-Jurassic transition in southern Peru is characterized by a cessation of continental extension (the "Mitu" rift) and renewed subduction related magmatism along the present-day coastline and inland region of the Arequipa massif, south of 12'S. Several continuous rock sections proximal to the coast of the Arequipa Terrane are interpreted to have originated in a continental are setting, which possibly commenced in the later Triassic (?) to Jurassic (Sempere et al., 2002). We speculate that the extensional geodynamic scenario which formed the Mitu Rift, may have terminated during renewed (orthogonal) subduction, giving rise to active margin magmatism. Understanding the timing and nature of Jurassic arc magmatism will also shed light on the reasons for the lack of Jurassic rocks in the 'craton-free zone', north of 12'S (north of Lima). Our project commenced with a detailed investigation of the Jurassic sedimentary and volcanic rocks along the Peruvian coastline between 15'S and 18.5'S The distribution and depositional ages of Jurassic are sequences are only tentatively constrained by inaccurate radiometric age data, and sparse fossil data (Martinez et al, unpublished) We will derive an accurate chronestratigraphic framework for the are sequences using the UPb and Ar Ar dating techniques. Furthermore, a detailed description of the facies distribution of both volcanic and sedimentary rocks, combined with a geochemical study, will allow us to distinguish between back-ure and continental arc volcanism, and hence constrain the tectonic and paleogeographic evolution of the region

An eHealth App (CAPABLE) Providing Symptom Monitoring, Well-Being Interventions, and Educational Material for Patients With Melanoma Treated With Immune Checkpoint Inhibitors: Protocol for an Exploratory Intervention Trial

BackgroundSince treatment with immune checkpoint inhibitors (ICIs) is becoming standard therapy for patients with high-risk and advanced melanoma, an increasing number of patients experience treatment-related adverse events such as fatigue. Until now, studies have demonstrated the benefits of using eHealth tools to provide either symptom monitoring or interventions to reduce treatment-related symptoms such as fatigue. However, an eHealth tool that facilitates the combination of both symptom monitoring and symptom management in patients with melanoma treated with ICIs is still needed. ObjectiveIn this pilot study, we will explore the use of the CAPABLE (Cancer Patients Better Life Experience) app in providing symptom monitoring, education, and well-being interventions on health-related quality of life (HRQoL) outcomes such as fatigue and physical functioning, as well as patients’ acceptance and usability of using CAPABLE. MethodsThis prospective, exploratory pilot study will examine changes in fatigue over time in 36 patients with stage III or IV melanoma during treatment with ICI using CAPABLE (a smartphone app and multisensory smartwatch). This cohort will be compared to a prospectively collected cohort of patients with melanoma treated with standard ICI therapy. CAPABLE will be used for a minimum of 3 and a maximum of 6 months. The primary endpoint in this study is the change in fatigue between baseline and 3 and 6 months after the start of treatment. Secondary end points include HRQoL outcomes, usability, and feasibility parameters. ResultsStudy inclusion started in April 2023 and is currently ongoing. ConclusionsThis pilot study will explore the effect, usability, and feasibility of CAPABLE in patients with melanoma during treatment with ICI. Adding the CAPABLE system to active treatment is hypothesized to decrease fatigue in patients with high-risk and advanced melanoma during treatment with ICIs compared to a control group receiving standard care. The Medical Ethics Committee NedMec (Amsterdam, The Netherlands) granted ethical approval for this study (reference number 22-981/NL81970.000.22). Trial RegistrationClinicalTrials.gov NCT05827289; https://clinicaltrials.gov/study/NCT05827289 International Registered Report Identifier (IRRID)DERR1-10.2196/4925