Neon isotopic signature applied to detrital provenance assignment in foreland basins

This work critically reviews the Eocene–Oligocene source-to-sink systems accumulating volcanogenic sequences in the basins around the Alps. Through the years, these volcanogenic sequences have been correlated to the plutonic bodies along the Periadriatic Fault System, the main tectonic lineament running from West to East within the axis of the belt. Starting from the large amounts of data present in literature, for the first time we present an integrated 4D model on the evolution of the sediment pathways that once connected the magmatic sources to the basins. The magmatic systems started to develop during the Eocene in the Alps, supplying detritus to the Adriatic Foredeep. The progradation of volcanogenic sequences in the Northern Alpine Foreland Basin is subsequent and probably was favoured by the migration of the magmatic systems to the North and to the West. At around 30 Ma, the Northern Apennine Foredeep also was fed by large volcanogenic inputs, but the palinspastic reconstruction of the Adriatic Foredeep, together with stratigraphic and petrographic data, allows us to safely exclude the Alps as volcanogenic sources. Beyond the regional case, this review underlines the importance of a solid stratigraphic approach in the reconstruction of the source-to-sink system evolution of any basin.

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Geochemical Variation of Miocene Basalts within Shikoku Basin: Magma Source Compositions and Geodynamic Implications

Minerals ◽

10.3390/min11010025 ◽

2020 ◽

Vol 11 (1) ◽

pp. 25

Author(s):

Shuang-Shuang Chen ◽

Tong Hou ◽

Jia-Qi Liu ◽

Zhao-Chong Zhang

Keyword(s):

Japan Sea ◽

Isotopic Signature ◽

Magma Source ◽

Isotopic Compositions ◽

Enriched Mantle ◽

Shikoku Basin ◽

Depleted Mantle ◽

Parece Vela Basin ◽

Back Arc ◽

Ocean Ridge

Shikoku Basin is unique as being located within a trench-ridge-trench triple junction. Here, we report mineral compositions, major, trace-element, and Sr-Nd-Pb isotopic compositions of bulk-rocks from Sites C0012 (>18.9 Ma) and 1173 (13–15 Ma) of the Shikoku Basin. Samples from Sites C0012 and 1173 are tholeiitic in composition and display relative depletion in light rare earth elements (REEs) and enrichment in heavy REEs, generally similar to normal mid-ocean ridge basalts (N-MORB). Specifically, Site C0012 samples display more pronounced positive anomalies in Rb, Ba, K, Pb and Sr, and negative anomalies in Th, U, Nb, and Ta, as well as negative Nb relative to La and Th. Site 1173 basalts have relatively uniform Sr-Nd-Pb isotopic compositions, close to the end member of depleted mantle, while Site C0012 samples show slightly enriched Sr-Nd-Pb isotopic signature, indicating a possible involvement of enriched mantle 1 (EM1) and EM2 sources, which could be attributed to the metasomatism of the fluids released from the dehydrated subduction slab, but with the little involvement of subducted slab-derived sedimentary component. Additionally, the Shikoku Basin record the formation of the back-arc basin was a mantle conversion process from an island arc to a typical MORB. The formation of the Shikoku Basin is different from that of the adjacent Japan Sea and Parece Vela Basin, mainly in terms of the metasomatized subduction-related components, the nature of mantle source, and partial melting processes.

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The δ13C, δ18O and Δ47 records in biogenic, pedogenic and geogenic carbonate types from paleosol-loess sequence and their paleoenvironmental meaning

Quaternary Research ◽

10.1017/qua.2020.109 ◽

2021 ◽

pp. 1-17

Author(s):

Kazem Zamanian ◽

Alex R. Lechler ◽

Andrew J. Schauer ◽

Yakov Kuzyakov ◽

Katharine W. Huntington

Keyword(s):

Land Snail ◽

Isotopic Signature ◽

Sediment Layer ◽

Isotopic Signatures ◽

Pedogenic Carbonates ◽

Rhine Valley ◽

Clumped Isotope ◽

Time Specific ◽

Sediment Layers ◽

Paleoenvironmental Reconstructions

Abstract Paleoenvironmental reconstructions are commonly based on isotopic signatures of a variety of carbonate types, including rhizoliths and land-snail shells, present in paleosol-loess sequences. However, various carbonate types are formed through distinct biotic and abiotic processes over various periods, and therefore may record diverging environmental information in the same sedimentological layer. Here, we investigate the effects of carbonate type on δ13C, δ18O, and clumped isotope-derived paleotemperature [T(Δ47)] from the Quaternary Nussloch paleosol-loess sequence (Rhine Valley, SW Germany). δ13C, δ18O, and T(Δ47) values of co-occurring rhizoliths (-8.2‰ to -5.8‰, -6.1‰ to -5.9‰, 12–32°C, respectively), loess dolls (-7.0‰, -5.6‰, 23°C), land-snail shells (-8.1‰ to -3.2‰, -4.0‰ to -2.2‰, 12–38°C), earthworm biospheroliths (-11‰, -4.7‰, 8°C), and “bulk” carbonates (-1.9‰ to -0.5‰, -5.6‰ to -5.3‰, 78–120°C) from three sediment layers depend systematically on the carbonate type, admixture from geogenic carbonate, and the duration of formation periods. Based on these findings, we provide a comprehensive summary for the application of the three isotopic proxies of δ13C, δ18O, and Δ47 in biogenic and pedogenic carbonates present in the same sediment layer to reconstruct paleoenvironments (e.g., local vegetation, evaporative conditions, and temperature). We conclude that bulk carbonates in Nussloch loess should be excluded from paleoenvironmental reconstructions. Instead, pedogenic and biogenic carbonates should be used to provide context for interpreting the isotopic signature for detailed site- and time-specific paleoenvironmental information.

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Coupling of stable carbon isotopic signature of methane and ebullitive fluxes in northern temperate lakes

The Science of The Total Environment ◽

10.1016/j.scitotenv.2021.146117 ◽

2021 ◽

pp. 146117

Author(s):

Shoji D. Thottathil ◽

Yves T. Prairie

Keyword(s):

Isotopic Signature ◽

Stable Carbon ◽

Temperate Lakes ◽

Carbon Isotopic

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Burial-deformation History of Folded Rocks Unraveled by Fracture Analysis, Stylolite Paleopiezometry and Vein Cement Geochemistry: A Case Study in the Cingoli Anticline (Umbria-Marche, Northern Apennines)

Geosciences ◽

10.3390/geosciences11030135 ◽

2021 ◽

Vol 11 (3) ◽

pp. 135

Author(s):

Aurélie Labeur ◽

Nicolas E. Beaudoin ◽

Olivier Lacombe ◽

Laurent Emmanuel ◽

Lorenzo Petracchini ◽

...

Keyword(s):

Isotope Geochemistry ◽

Central Italy ◽

Microstructural Analysis ◽

Northern Apennines ◽

Foreland Basins ◽

Deformation History ◽

The North ◽

Regional Tectonic ◽

History Of ◽

Clumped Isotope

Unravelling the burial-deformation history of sedimentary rocks is prerequisite information to understand the regional tectonic, sedimentary, thermal, and fluid-flow evolution of foreland basins. We use a combination of microstructural analysis, stylolites paleopiezometry, and paleofluid geochemistry to reconstruct the burial-deformation history of the Meso-Cenozoic carbonate sequence of the Cingoli Anticline (Northern Apennines, central Italy). Four major sets of mesostructures were linked to the regional deformation sequence: (i) pre-folding foreland flexure/forebulge; (ii) fold-scale layer-parallel shortening under a N045 σ1; (iii) syn-folding curvature of which the variable trend between the north and the south of the anticline is consistent with the arcuate shape of the anticline; (iv) the late stage of fold tightening. The maximum depth experienced by the strata prior to contraction, up to 1850 m, was quantified by sedimentary stylolite paleopiezometry and projected on the reconstructed burial curve to assess the timing of the contraction. As isotope geochemistry points towards fluid precipitation at thermal equilibrium, the carbonate clumped isotope thermometry (Δ47) considered for each fracture set yields the absolute timing of the development and exhumation of the Cingoli Anticline: layer-parallel shortening occurred from ~6.3 to 5.8 Ma, followed by fold growth that lasted from ~5.8 to 3.9 Ma.

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