Neotethyan Subduction Ignited the Iran Arc and Backarc Differently

Most arcs show systematic temporal and spatial variations in magmatism with clear shifts in igneous rock compositions between those of the magmatic front (MF) and those in the backarc (BA). It is unclear if similar magmatic polarity is seen for extensional continental arcs. Herein, we use geochemical and isotopic characteristics coupled with zircon U‐Pb geochronology to identify the different magmatic style of the Iran convergent margin, an extensional system that evolved over 100 Myr. Our new and compiled U‐Pb ages indicate that major magmatic episodes for the NE Iran BA occurred at 110–80, 75–50, 50–35, 35–20, and 15–10 Ma. In contrast to NE Iran BA magmatic episodes, compiled data from MF display two main magmatic episodes at 95–75 and 55–5 Ma, indicating more continuous magmatism for the MF than for the BA. We show that Paleogene Iran serves as a useful example of a continental arc under extension. Our data also suggest that there is not a clear relationship between the subduction velocity of Neotethyan Ocean beneath Iran and magmatic activity in Iran. Our results imply that the isotopic compositions of Iran BA igneous rocks do not directly correspond to the changes in tectonic processes or geodynamics, but other parameters such as the composition of lithosphere and melt source(s) should be considered. In addition, changes in subduction zone dynamics and contractional versus extensional tectonic regimes influenced the composition of MF and BA magmatic rocks. These controls diminished the geochemical and isotopic variations between the magmatic front and backarc

Small Molecule, Non-Peptide p75NTR Ligands Inhibit Aβ-Induced Neurodegeneration and Synaptic Impairment

The p75 neurotrophin receptor (p75NTR) is expressed by neurons particularly vulnerable in Alzheimer's disease (AD). We tested the hypothesis that non-peptide, small molecule p75NTR ligands found to promote survival signaling might prevent Aβ-induced degeneration and synaptic dysfunction. These ligands inhibited Aβ-induced neuritic dystrophy, death of cultured neurons and Aβ-induced death of pyramidal neurons in hippocampal slice cultures. Moreover, ligands inhibited Aβ-induced activation of molecules involved in AD pathology including calpain/cdk5, GSK3β and c-Jun, and tau phosphorylation, and prevented Aβ-induced inactivation of AKT and CREB. Finally, a p75NTR ligand blocked Aβ-induced hippocampal LTP impairment. These studies support an extensive intersection between p75NTR signaling and Aβ pathogenic mechanisms, and introduce a class of specific small molecule ligands with the unique ability to block multiple fundamental AD-related signaling pathways, reverse synaptic impairment and inhibit Aβ-induced neuronal dystrophy and death

Role of Mutagenicity in Asbestos Fiber-Induced Carcinogenicity and Other Diseases

The cellular and molecular mechanisms of how asbestos fibers induce cancers and other diseases are not well understood. Both serpentine and amphibole asbestos fibers have been shown to induce oxidative stress, inflammatory responses, cellular toxicity and tissue injuries, genetic changes, and epigenetic alterations in target cells in vitro and tissues in vivo. Most of these mechanisms are believe to be shared by both fiber-induced cancers and noncancerous diseases. This article summarizes the findings from existing literature with a focus on genetic changes, specifically, mutagenicity of asbestos fibers. Thus far, experimental evidence suggesting the involvement of mutagenesis in asbestos carcinogenicity is more convincing than asbestos-induced fibrotic diseases. The potential contributions of mutagenicity to asbestos-induced diseases, with an emphasis on carcinogenicity, are reviewed from five aspects: (1) whether there is a mutagenic mode of action (MOA) in fiber-induced carcinogenesis; (2) mutagenicity/carcinogenicity at low dose; (3) biological activities that contribute to mutagenicity and impact of target tissue/cell type; (4) health endpoints with or without mutagenicity as a key event; and finally, (5) determinant factors of toxicity in mutagenicity. At the end of this review, a consensus statement of what is known, what is believed to be factual but requires confirmation, and existing data gaps, as well as future research needs and directions, is provided

Origin and evolution of ore-forming fluids of San Dimas deposits

The San Dimas district is a world-class Ag/Au deposit, developed as a telescoped Eocene-Oligocene Ag/Au mineralization located in the Sierra Madre Occidental (SMO) of western Mexico. San Dimas exhibits multiple mineralization events during different magmatic and tectonic episodes from Late Cretaceous to early Oligocene. The well-preserved magmatic-hydrothermal system provides an excellent opportunity to determine the source of silver and gold, the evolution of the hydrothermal fluids, and the controls on the mineralization precipitation. Mineralogical, fluid inclusions, stable and noble gases isotope analyses suggest that the San Dimas deposit consist of two different mineralization styles: 1) Ag-dominant mesothermal Eocene veins that occurred at temperatures > 300ºC developed at ca. 3 km depth, associated to the final stages of intrusion of the Piaxtla batholith, and 2) epithermal low sulfidation Au-dominant Oligocene veins which were developed at 250ºC, at shallower depths (<1km), associated to the feeding fractures of rhyolitic domes developed at the end of the main ignimbrite flare up of the SMO. Our results highlight the importance of a multidisciplinary approach, such as field observations, geochronological and geochemical studies, to better understand the complexity of the hydrothermal magmatic processes involved in the formation of many Mexican ore deposits and their proper classification

Origin and evolution of ore-forming fluids of San Dimas deposits

The San Dimas district is a world-class Ag/Au deposit, developed as a telescoped Eocene-Oligocene Ag/Au mineralization located in the Sierra Madre Occidental (SMO) of western Mexico. San Dimas exhibits multiple mineralization events during different magmatic and tectonic episodes from Late Cretaceous to early Oligocene. The well-preserved magmatic-hydrothermal system provides an excellent opportunity to determine the source of silver and gold, the evolution of the hydrothermal fluids, and the controls on the mineralization precipitation. Mineralogical, fluid inclusions, stable and noble gases isotope analyses suggest that the San Dimas deposit consist of two different mineralization styles: 1) Ag-dominant mesothermal Eocene veins that occurred at temperatures > 300ºC developed at ca. 3 km depth, associated to the final stages of intrusion of the Piaxtla batholith, and 2) epithermal low sulfidation Au-dominant Oligocene veins which were developed at 250ºC, at shallower depths (<1km), associated to the feeding fractures of rhyolitic domes developed at the end of the main ignimbrite flare up of the SMO. Our results highlight the importance of a multidisciplinary approach, such as field observations, geochronological and geochemical studies, to better understand the complexity of the hydrothermal magmatic processes involved in the formation of many Mexican ore deposits and their proper classification

Data for: Short term evaporation estimation in a natural semiarid environment: new perspective of the Craig - Gordon isotopic model.

Biannual hydrogeologic cycle characterization in a natural semi arid environment, we have applied and compared Craig-Gordon isotopic model with the Penman physical evaporation model. Results presented include rain water, atmospheric water vapor, agricultural pool water, isotopic evaporation loss and Penman evaporation estimation Physical and isotopic methodologies are difficult to relate due to basic fundamentals and development conceptualizations. Further work is required to enhance the Craig-Gordon and Gonfiantini evaporation model and its relationship with physical methodologies to obtain accurate estimations in evaporation in natural semiarid environments

Data for: Short term evaporation estimation in a natural semiarid environment: new perspective of the Craig - Gordon isotopic model.

Biannual hydrogeologic cycle characterization in a natural semi arid environment, we have applied and compared Craig-Gordon isotopic model with the Penman physical evaporation model. Results presented include rain water, atmospheric water vapor, agricultural pool water, isotopic evaporation loss and Penman evaporation estimation Physical and isotopic methodologies are difficult to relate due to basic fundamentals and development conceptualizations. Further work is required to enhance the Craig-Gordon and Gonfiantini evaporation model and its relationship with physical methodologies to obtain accurate estimations in evaporation in natural semiarid environments.THIS 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

Origin and evolution of ore-forming fluids of San Dimas deposits

The San Dimas district is a world-class Ag/Au deposit, developed as a telescoped Eocene-Oligocene Ag/Au mineralization located in the Sierra Madre Occidental (SMO) of western Mexico. San Dimas exhibits multiple mineralization events during different magmatic and tectonic episodes from Late Cretaceous to early Oligocene. The well-preserved magmatic-hydrothermal system provides an excellent opportunity to determine the source of silver and gold, the evolution of the hydrothermal fluids, and the controls on the mineralization precipitation. Mineralogical, fluid inclusions, stable and noble gases isotope analyses suggest that the San Dimas deposit consist of two different mineralization styles: 1) Ag-dominant mesothermal Eocene veins that occurred at temperatures > 300ºC developed at ca. 3 km depth, associated to the final stages of intrusion of the Piaxtla batholith, and 2) epithermal low sulfidation Au-dominant Oligocene veins which were developed at 250ºC, at shallower depths (<1km), associated to the feeding fractures of rhyolitic domes developed at the end of the main ignimbrite flare up of the SMO. Our results highlight the importance of a multidisciplinary approach, such as field observations, geochronological and geochemical studies, to better understand the complexity of the hydrothermal magmatic processes involved in the formation of many Mexican ore deposits and their proper classification

Origin and evolution of ore-forming fluids of San Dimas deposits

The San Dimas district is a world-class Ag/Au deposit, developed as a telescoped Eocene-Oligocene Ag/Au mineralization located in the Sierra Madre Occidental (SMO) of western Mexico. San Dimas exhibits multiple mineralization events during different magmatic and tectonic episodes from Late Cretaceous to early Oligocene. The well-preserved magmatic-hydrothermal system provides an excellent opportunity to determine the source of silver and gold, the evolution of the hydrothermal fluids, and the controls on the mineralization precipitation. Mineralogical, fluid inclusions, stable and noble gases isotope analyses suggest that the San Dimas deposit consist of two different mineralization styles: 1) Ag-dominant mesothermal Eocene veins that occurred at temperatures > 300ºC developed at ca. 3 km depth, associated to the final stages of intrusion of the Piaxtla batholith, and 2) epithermal low sulfidation Au-dominant Oligocene veins which were developed at 250ºC, at shallower depths (<1km), associated to the feeding fractures of rhyolitic domes developed at the end of the main ignimbrite flare up of the SMO. Our results highlight the importance of a multidisciplinary approach, such as field observations, geochronological and geochemical studies, to better understand the complexity of the hydrothermal magmatic processes involved in the formation of many Mexican ore deposits and their proper classification

Comment on “Basinal Brines at the Origin of the Imiter Ag–Hg Deposit (Anti-Atlas, Morocco): Evidence from LA-ICP-MS Data on Fluid Inclusions, Halogen Signatures, and Stable Isotopes (H, C, O)” by Essaraj et al

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