Holocene Sedimentary Record and Coastal Evolution in the Makran Subduction Zone (Iran)

The western Makran coast displays evidence of surface uplift since at least the Late Pleistocene, but it remains uncertain whether this displacement is accommodated by creep on the subduction interface, or in a series of large earthquakes. Here, we address this problem by looking at the short-term (Holocene) history of continental vertical displacements recorded in the geomorphology and sedimentary succession of the Makran beaches. In the region of Chabahar (Southern Iran), we study two bay-beaches through the description, measurement and dating of 13 sedimentary sections with a combination of radiocarbon and Optically Stimulated Luminescence (OSL) dating. Our results show that lagoonal settings dominate the early Holocene of both studied beach sections. A flooding surface associated with the Holocene maximum transgression is followed by a prograding sequence of tidal and beach deposits. Coastal progradation is evidenced in Pozm Bay, where we observe a rapid buildup of the beach ridge succession (3.5 m/years lateral propagation over the last 1950 years). Dating of Beris Beach revealed high rates of uplift, comparable to the rates obtained from the nearby Late Pleistocene marine terraces. A 3150-year-old flooding surface within the sedimentary succession of Chabahar Bay was possibly caused by rapid subsidence during an earthquake. If true, this might indicate that the Western Makran does produce large earthquakes, similar to those that have occurred further east in the Pakistani Makran

Dating and morpho-stratigraphy of uplifted marine terraces in the Makran subduction zone (Iran)

The western part of the Makran subduction zone (Iran) is currently experiencing active surface uplift, as attested by the presence of emerged marine terraces along the coast. To better understand the uplift recorded by these terraces, we investigated seven localities along the Iranian Makran and we performed radiocarbon, 230Th∕U and optically stimulated luminescence (OSL) dating of the layers of marine sediments deposited on top of the terraces. This enabled us to correlate the terraces regionally and to assign them to different Quaternary sea-level highstands. Our results show east–west variations in surface uplift rates mostly between 0.05 and 1.2 mm yr−1. We detected a region of anomalously high uplift rate, where two MIS 3 terraces are emerged, but we are uncertain how to interpret these results in a geologically coherent context. Although it is presently not clear whether the uplift of the terraces is linked to the occurrence of large megathrust earthquakes, our results highlight rapid surface uplift for a subduction zone context and heterogeneous accumulation of deformation in the overriding plate

Membrane assembly and ion transport ability of a fluorinated nanopore

A novel 21-residue peptide incorporating six fluorinated amino acids was prepared. It was designed to fold into an amphiphilic alpha helical structure of nanoscale length with one hydrophobic face and one fluorinated face. The formation of a fluorous interface serves as the main vector for the formation of a superstructure in a bilayer membrane. Fluorescence assays showed this ion channel's ability to facilitate the translocation of alkali metal ions through a phospholipid membrane, with selectivity for sodium ions. Computational studies showed that a tetramer structure is the most probable and stable supramolecular assembly for the active ion channel structure. The results illustrate the possibility of exploiting multiple Fd-:M+ interactions for ion transport and using fluorous interfaces to create functional nanostructures

Pressure-temperature-time evolution in the high-grade metamorphic basement of the Siviez-Mischabel nappe (Val d'Hérens, Val d'Anniviers)

The Banded amphibolites, a mafic layer situated at the base of the Adlerflüe Formation in the basement of the Sivez-Mischabel (SM) nappe (Valais, CH), contain local occurrences of eclogite; witnesses of a pre-Alpine high-grade metamorphic event. They have a composition of NMORB enriched in LILE, U, Th, Pb and LREE which are characteristic for a back-arc depositional environment. The pressure-temperature time path was modelled for these eclogite occurrences using the program DOMINO and the garnet-clinopyroxene Fe2+-Mg geothermometer. Peak metamorphic conditions were estimated to be 15-17 kbar and 650-800°C. The retrograde event, responsible for the breakdown of omphacite and the growth of pargasite is estimated at approximatively 8 kbar and 500-600°C, which places it in the amphibolite facies. The age of the youngest zircon within the SOPA (“schistes oeillés à porphyroblastes d'albite”), a metasedimentary unit directly overlying the eclogites, was determined to be 520.9±7.1 Ma which, together with the age of the crosscutting Thyon metagranite (500+3-4 Ma), provides an age window for the deposition of the SOPA. Timing of the emplacement of the Banded amphibolites and related rocks can therefore be constrained to the mid to late Cambrian. The recrystallized domains in zircon of all studied rock types yield coherent ages, with a calculated mean value of 346.58±0.97 Ma. This lower Carboniferous age is consistent with the ultra-high pressure events linked to the Variscan orogeny and is proposed as the age of the eclogitic metamorphism in the Siviez-Mischabel nappe

Geomorphological, sedimentological and structural signals of deformation in a silent subduction zone: an investigation of the Makran (Iran)

The Makran subduction zone of southeastern Iran has not experienced a megathrust earthquake in recent history, yet, the presence of uplifted coastal morphologies indicate that the margin is still tectonically active. In this work, we study three types of geological signals of deformation that might be linked to the occurrence of large earthquakes in this region. Makran marine terraces have unique morphologies and sedimentary successions. Their mapping and dating allowed us to calculate Late Pleistocene uplift rate variations along the coast. Recent vertical displacements associated with large earthquakes are investigated into the sedimentary succession of low-lying Holocene bay beaches. Finally, we speculate that the normal faults observed along the coast, in an apparently compressive tectonic context, might be linked to post-seismic relaxation following great subduction earthquakes. Although the western Makran is seemingly aseismic for the last 500 years, geological evidences suggests that large events might have happened in the past

Pleistocene Coastal Evolution in the Makran Subduction Zone

Along the coast of the Makran subduction zone (SE Iran and SW Pakistan), active uplift combined with efficient erosion and vigorous sediment transport have led to marine terraces with unique morphology and sedimentology. These terraces are characterized by the systematic presence of an extensive 1–10Cm thick sandstone layer capping their wave-cut base. Our investigation of thirty-six sedimentary logs of the terrace deposits revealed a general prograding trend from nearshore to beach deposits moving upsection. The presence of a thick marine sedimentary succession above the erosive platform suggests continued creation of accommodation space following carving of the platform by wave-erosion (i.e., erosion of the platform occurred before the peak of the highstand). Deposition of prograding beaches above the platform is interpreted to have occurred during the sea-level stillstand and the start of sea-level fall and was favored by a high sedimentary supply. While some terraces evolve into a classic staircase morphology, others are found as flat-topped platforms bounded by steep cliffs, isolated within the low-lying coastal plain. We find that this morphological difference results from a contrast in bedrock erodability (resistant sandstone versus soft marl, respectively). The flat-topped isolated marine terraces with marl bedrock share morphological and sedimentological similarities with Holocene crenulated beaches currently developing in low-lying bays between headlands. As indurated beaches are uplifted into headlands, they influence the development of following generations of beaches before being eroded by surficial erosion and wave action. Our study shows that the coastal geomorphology of the Makran coast is dictated by the interaction between tectonics (providing relative sea-level fall and juxtaposing units of different erodability at the same structural level by faulting), differential erosion between hard and soft rock (responsible for the presence of isolated headlands) and coastal sedimentary transport processes (permitting accumulation of extensive beach deposits)

Acute cytokine release syndrome after a first dose of pembrolizumab as second-line treatment for metastatic, programmed death-ligand 1-positive, non-small-cell lung cancer

Introduction: The use of programmed death-ligand 1 (PD-L1) checkpoint inhibitor therapy is expanding, although its adverse effects are not completely known. We report on a rare case of acute cytokine release syndrome related to pembrolizumab use in a patient with lung cancer. Case report: A 79-year-old man with metastatic, PD-L1-positive, non-small-cell lung cancer developed a febrile condition associated with a systemic inflammatory response syndrome and suffered haemodynamic compromise four hours after the first intravenous administration of pembrolizumab. A thorough medical workup found no alternative cause and a grade 2 cytokine release syndrome (CRS) was diagnosed. Management and outcome: Aggressive fluid resuscitation and supportive therapy led to restitutio ad integrum. Discussion: Acute CRS after the administration of a PD-L1 inhibitor is infrequent but could be a fatal condition. Supportive treatment and, if necessary, corticosteroids should be considered