American Journal of Science https://ajsonline.org/ Founded in 1818 by Benjamin Silliman. The Journal is devoted to geology and related sciences. en Facies Vectors: Disentangling Environmental Variability, Diagenesis, and Secular Change in Carbonate Stratigraphies Mon, 08 Jun 2026 19:39:53 +0000 We represent sampled points in a lower Cambrian section using field observations, image analyses, and geochemical measurements to test the null hypothesis of stratigraphic stasis. https://doi.org/10.2475/001c.161588 https://ajsonline.org/article/161588-facies-vectors-disentangling-environmental-variability-diagenesis-and-secular-change-in-carbonate-stratigraphies Reversed Inter-Mineral Fe-Zn Isotope Fractionation in Ophiolitic Peridotites: Evidence for Widespread Hydration of Oceanic Lithospheric Mantle Wed, 22 Apr 2026 16:25:31 +0000 Fluid-assisted element exchange and subsolidus diffusion in various lithologies of the oceanic lithospheric mantle produce reversed inter-mineral isotope fractionation. https://doi.org/10.2475/001c.160209 https://ajsonline.org/article/160209-reversed-inter-mineral-fe-zn-isotope-fractionation-in-ophiolitic-peridotites-evidence-for-widespread-hydration-of-oceanic-lithospheric-mantle Dependence of River Water Lithium Isotope Ratios on Watershed Attributes Complicates Interpretation of Weathering-Driven CO~2~ Drawdown Mon, 30 Mar 2026 14:18:30 +0000 ... https://doi.org/10.2475/001c.157531 https://ajsonline.org/article/157531-dependence-of-river-water-lithium-isotope-ratios-on-watershed-attributes-complicates-interpretation-of-weathering-driven-co-2-drawdown Heterogeneous Carbonate Lithium Isotope Records Across the end-Permian Mass Extinction Indicate a Highly Perturbed Lithium Cycle in the Early Triassic Mon, 23 Mar 2026 15:10:25 +0000 Variations in Early Triassic carbonate lithium isotopes are hypothesized to reflect diagenetic alteration and a poorly mixed oceanic Li reservoir that developed from extensive reverse weathering. https://doi.org/10.2475/001c.156171 https://ajsonline.org/article/156171-heterogeneous-carbonate-lithium-isotope-records-across-the-end-permian-mass-extinction-indicate-a-highly-perturbed-lithium-cycle-in-the-early-triassic Carbon Isotope Trends of Precambrian-Cambrian Carbonates in Southwestern Laurentia Are Robust to Diagenetic Overprinting Fri, 13 Feb 2026 16:48:50 +0000 Carbon isotope (δ^13^C) stratigraphic trends across the Precambrian-Cambrian boundary in southwestern Laurentia are insensitive to diagenetic overprinting despite an increase in fluid-buffered marine diagenesis. https://doi.org/10.2475/001c.155346 https://ajsonline.org/article/155346-carbon-isotope-trends-of-precambrian-cambrian-carbonates-in-southwestern-laurentia-are-robust-to-diagenetic-overprinting Permian Syn-Extensional Barrovian Metamorphism in the Envelope of a Migmatite Dome of the Mongolian Altai – Petrostructural and Geochronological Arguments Mon, 09 Feb 2026 21:00:47 +0000 Petrochronology demonstrates that Barrovian metamorphism around a Permian metamorphic core complex in the Mongolian Altai, previously considered a signature of crustal thickening, was instead produced during crustal thinning. https://doi.org/10.2475/001c.155605 https://ajsonline.org/article/155605-permian-syn-extensional-barrovian-metamorphism-in-the-envelope-of-a-migmatite-dome-of-the-mongolian-altai-petrostructural-and-geochronological-argum From Source Rock to Cinnabar – How the Giant Mercury Deposits in Earth’s Crust Formed Tue, 20 Jan 2026 20:56:31 +0000 Mercury isotopes in cinnabar suggest an upper mantle origin, as 85% of samples plot near the origin, matching compositions from continental flood basalts like the Siberian Traps. https://doi.org/10.2475/001c.147533 https://ajsonline.org/article/147533-from-source-rock-to-cinnabar-how-the-giant-mercury-deposits-in-earth-s-crust-formed A Basin in Transition: Ecological, Environmental, and Tectonic Shifts Across the Ediacaran–Cambrian Boundary in the Nama Group, Kalahari Craton Sat, 03 Jan 2026 01:38:25 +0000 New research on late Ediacaran–early Cambrian stratigraphy of Namibia’s Nama Group revises biostratigraphic and chemostratigraphic age models for the terminal Ediacaran and advances understanding of the Nama Foreland Basin. https://doi.org/10.2475/001c.151699 https://ajsonline.org/article/151699-a-basin-in-transition-ecological-environmental-and-tectonic-shifts-across-the-ediacaran-cambrian-boundary-in-the-nama-group-kalahari-craton Rare Earth Element-Mineralized Carbonatite in the Bear Lodge Alkaline Complex, USA—Ore Genesis Implications From Fluid Inclusion Characterization Fri, 17 Oct 2025 15:14:04 +0000 Study of fluid inclusions in carbonatite of the Bear Lodge Alkaline Complex, Wyoming shows that alkali bicarbonate-sulfate brines were integral to early, light rare earth element mineralization within carbonatite intrusions. https://doi.org/10.2475/001c.143992 https://ajsonline.org/article/143992-rare-earth-element-mineralized-carbonatite-in-the-bear-lodge-alkaline-complex-usa-ore-genesis-implications-from-fluid-inclusion-characterization Balancing Redox Budgets: Mechanisms for Prolonging Anoxia During Major Carbon Burial Events Thu, 11 Sep 2025 15:27:42 +0000 Oceanic Anoxic Events likely produced excess oxygen from burial of reduced carbon and sulfur, but Large Igneous Province reductants and oxidative weathering may balance this to maintain marine anoxia. https://doi.org/10.2475/001c.143665 https://ajsonline.org/article/143665-balancing-redox-budgets-mechanisms-for-prolonging-anoxia-during-major-carbon-burial-events