Posters virtual: Fri, 2 May, 14:00–15:45 | vPoster spot 5
Drought significantly affects the growth and physiological responses of Zagros forests, one of the most important natural habitats in Iran. The Brants oak (Quercus brantii Lindl), a widely distributed and dominant tree species in the Central Zagros Mountains of western Iran, serves as a valuable natural archive for studying historical climate variability and ecological changes. For climate-growth analysis, 30 Q. brantii trees cored from Lordegan area (1820 to 2280 m a.s.l.) in the southwest of Zagros forests of Iran. After preparing the samples, measuring the tree ring widths and cross-dating developed the tree ring chronology (1710-2023) using dplR. The relationships between tree-ring widths (TRW) and monthly mean temperature and precipitation values and the Standardized Precipitation Evapotranspiration Index (SPEI) were analyzed. The strongest climate signal of SPEI was found from previous September until April, representing the pre-growing and early-growing seasons. Among these reconstructions were acknowledged extremely narrow rings in 1870, 1923, 1960, 1964, and 2018, while extremely large rings were found in 1784, 1852, 1957, and 1976. Based on preliminary calculations showing a strong winter SPEI signal, this chronology could be used for climate reconstruction, but further analysis is required. These studies indicate the vulnerability of oak forests in the Zagros Mountains to ongoing climate change and a pressing need for sustainable forest management strategies to preserve these vital ecosystems.
Keywords: Zagros forests, Iran, Quercus brantii, reconstruction, tree-ring widths
How to cite: Hatami, F., Klesse, S., Treydte, K., Verstege, A., Etemad, V., Pourtahmasi, K., Gessler, A., and Iranmanesh, Y.: Potential for a 300-year drought reconstruction in the Zagros Mountains, Iran based on the tree-ring width of Quercus brantii Lindl. , EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-10067, https://doi.org/10.5194/egusphere-egu25-10067, 2025.
Powerful volcanic eruptions inject into the stratosphere sulphur and tephra that may be spread globally and affect the Earth’s climate. Over the last 2500 years, Sigl et al. (2015) made a synthesis of the polar ice core atmospheric sulphur record and climate anomalies from dendrochronological records. Aside from a few historical events, most large eruptions with a bipolar imprint and a significant climate anomaly are from the tropical latitudes, but their sources are unknown.
We analysed the micron-size crytotephra composition accompanying the (stratospheric) sulphate of the 1458 CE and 426 BCE volcanic events recorded in three Antarctic ice cores. The 1458 CE event occurred within a cool climate and was initially attributed to the Kuwae (Vanuatu) eruption. This link is however questioned by Hartman et al. (2019) from their study of a South Pole ice core. The 426 BCE event appears concomitant with a significant global climate cooling, but its source is unknown.
Within the sulphate peak, the particle size distribution, when available, helps documenting the dynamics of the arrival of the stratospheric plume. Cryptotephra are collected by filtration and after carbon-coating, analysed by an EPMA microprobe. We applied the analytical procedure of Narcisi et al. (2019) (who identified the 1257 CE Samalas eruption), adapted to the micron-size of the crytotephra.
For the 1458 CE event, a medium-K dacite to rhyolite composition is consistently observed from Vostok and Dome C ice core samples (218 values). The dacite patch (SiO2~68%) fits well the composition of proximal Kuwae deposits as well as that of an ash layer (~140 values) on Efate Island (Standberg et al, 2023). The rhyolite composition patch (SiO2~72%) is unlikely from a South American source, but appears discretely represented in proximal Kuwae deposits as well as in sediments in the nearby Epi Submarine zone. We suggest that rhyolite is a daughter product from dacite by evolving in the upper layers of the magmatic chamber, and it was spread out first and far away by the eruption.
For the 426 BCE event, the cryptotephra composition (220 values) is consistently found within the three ice cores (Vostok, Dome C, Talos Dome) and belongs to high-K rhyodacite. Coincidentally such composition is very close to Kuwae’s (except for higher K) suggesting it was issued from a very similar magmatic chamber. The 10 km wide Ambrym caldera located 50 km north of Kuwae, collapsed ~2000 years ago appears the best candidate.
References
Hartman et al. (2019). Nature Sci. Rep. 9. https://doi.org/10.1038/s41598-019-50939-x.
Narcisi, B. et al., 2019. Quat. Sci. Rev. 210, 164-174 https://doi.org/10.1016/j.quascirev.2019.03.005.
Sigl, M., et al. Nature 523, 543–549 (2015). https://doi.org/10.1038/nature14565
Strandberg NA et al., (2023). Front. Ecol. Evol. 11: 1087577.doi: 10.3389/fevo.2023.1087577
How to cite: Petit, J.-R., Savarino, J., Delmonte, B., Gautier, E., Ginot, P., and Batanova, V.: Cryptotephra fingerprinting of 1458 CE and 426 BCE volcanic events in East Antarctic ice cores, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-2329, https://doi.org/10.5194/egusphere-egu25-2329, 2025.
Aeolian mineral dust and diatom influxes at the summit of Roosevelt Island (79.364°S, 161.706°W, 550 m a.s.l.) were investigated over the last 2 kyrs from the RICE ice core (Bertler et al., 2018). Mineral dust at the site is mainly related to large-scale atmospheric circulation patterns within the Eastern Ross and Amundsen Seas, while aeolian diatoms, mainly consisting of Fragilariopsis spp. (F. nana , F. cylindrus, , F. curta), depend on the local oceanic influence of air masses from the marine boundary layer. Thus, the complementarity of these proxies allows appreciating climatic and atmospheric changes experienced at Roosevelt Island over the last 2000 years, in response to some major forcing factors such as ENSO. During the 550-1470 CE period, when higher/less depleted stable water isotope values are observed, the increased importance of blocking ridges in the Amundsen Sea and a weakened Amundsen Sea Low promoted dust-rich air mass advection to RICE. This pattern was accompanied by an increasing trend in snow accumulation and reduced sea ice in the Eastern Ross and Amundsen Seas. At about 1300 CE, the maximum expression of the Ross Sea dipole is reached, with enhanced katabatic outflow in the Western Ross Sea and reactivation of the Ross Sea polynya. At the same time, the Eastern part of the Ross Sea was still under the influence of blocking ridges promoting maritime air mass advection to RICE and southward shift of the South Westerly Winds. After 1470 CE, unprecedented peaks of aeolian diatom concentration suggest a rapid reorganization of local atmospheric circulation, that probably occurred in relation to the eastward enlargement of the Ross Sea polynya culminating with the opening of the Roosevelt Island polynya.
For the RICE site, we suggest that several drivers contribute to the long-term dust, sea-ice and polynya variability, but ENSO-driven teleconnections are particularly prominent. On a longer (multidecadal) timescale it seems that El Niño-dominating conditions promoted the establishment of the Ross Sea dipole, while La Niña conditions favored a deeper Amundsen Sea Low and an eastward expansion of the polynya.
How to cite: Delmonte, B., Lagorio, S., Tetzner, D., Malinverno, E., and Bertler, N.: Aeolian dust and diatoms at Roosevelt Island (Ross Sea, Antarctica) over the last two millennia reveal the local expression of climate changes and the history of the Ross Sea polynya., EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-8574, https://doi.org/10.5194/egusphere-egu25-8574, 2025.
Located in the arid inland of Asia, the eastern part of the Silk Road is marked by certain routes being close to or even crossing large deserts, such as the Taklimakan Desert, one of the largest deserts worldwide. As a result, sand and dust activities have a considerable impact on the transport routes, the desert-oasis ecosystem, and human society along the Silk Road. However, the evolution of dust activity over the past two millennia and its relation to the changes of the Silk Road civilization remains ambiguous. Here, we present a high-resolution (~3 yr) stalagmite record from Xinjiang (northwest China) spanning the past 2,500 years, dated with 19 U/Th ages. Although the stable isotopes and trace elemental ratios of the stalagmite reveal remarkable decadal- to centennial-scale variability of the regional hydroclimate, the Mg/Ca ratio shows a quite different variation pattern compared with other geochemical proxies. Considering various factors that might influence the Mg/Ca ratio of stalagmites, our analysis reached the conclusion that the geographical location close to the desert made the imported dust likely to predominate the increase of Mg/Ca in stalagmites during many characteristic periods. For instance, we found significant increases in the Mg/Ca ratios lasting for more than two centuries during approximately 650-850 CE and 1650-1950 CE (i.e., the Little Ice Age). This generally demonstrates a pattern of reduced dust activities during the Medieval Warm Period and enhanced dust activities throughout the Little Ice Age, which is supported by evidence from the eolian sedimentary section in the southern margin of the Taklimakan Desert that directly reflects dust activity. We further found that the enhanced dust activity during the 650-850 CE might have caused the route shift of the Silk Road from south to north in the Tarim Basin. In addition, the rapid drying of Lop Nur in recent decades could also be attributed to abnormally increased dust activity, as this period was characterized by the most intense dust activity in our records over the last 2,000 years. Our findings further substantiate the argument regarding the association between societal and climatic change along the Silk Road, where the dust production from large deserts poses challenges to sustainable development in the present and the future.
How to cite: Liu, X., Chen, S., Chen, J., Wang, H., Shen, C.-C., Wang, X., and Chen, F.: Reconstruction of dust activity using geochemical proxy from cave stalagmite in the northern Taklimakan Desert, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-12114, https://doi.org/10.5194/egusphere-egu25-12114, 2025.
The climatic signals recorded by loess sequences vary between different regions, which makes it important to study loess sequences worldwide. The loess deposits in northern Iran are situated in the transitional zone between the European loess and Central Asian loess. However, the depositional dynamics and paleoenvironmental significance of the loess deposits in this region are not well understood, making it difficult to establish detailed correlations with loess deposits elsewhere, partly due to the lack of systematic and high-resolution chronological control. We used K-feldspar pIR50IR290 and MET-pIRIR250 luminescence dating protocols to date fifty-two K-feldspar samples from the Toshan-19 section in the northern foothills of the Alborz Mountains, northern Iran. These chronological data, along with the climate proxies of magnetic susceptibility and redness, combined with a comparison with published loess records from various regions, indicate the following: (1) K-feldspar luminescence ages obtained using pIRIR and MET-pIRIR protocols are consistent, and their luminescence ages up to ~200 ka are deemed dependable. The loess at Toshan was primarily deposited during 78–24 ka, corresponding to MIS 4–2, and the paleosols developed during 139–78, and 24–1.7 ka, corresponding respectively to MIS 5, and late MIS 2–MIS 1. (2) Drier conditions prevailed during the last glacial and wetter conditions dominated during the last interglacial. Moisture variations during the substages of MIS 5 in this region indicate cold-dry and warm-wet climatic characteristics. The reasons for increased moisture from late MIS 2 onwards in this region still require further investigation. (3) The loess-paleosol records indicate a consistent pattern of climate change over Eurasia on the scale of the last interglacial-glacial cycle. During the substages of MIS 5, warm-wet and cold-dry conditions in northern Iran were in-phase with those on the Chinese Loess Plateau, Europe, and southern Tajikistan; however, they were anti-phased or out-of-phase with those in Xinjiang.
How to cite: Li, D., zhao, H., and Xie, H.: Loess-paleosol sedimentological characteristics in northern Iran since the last interglacial and their paleoenvironmental significance, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-16630, https://doi.org/10.5194/egusphere-egu25-16630, 2025.
Oases are critical locations for human survival in desert areas. With heavily reliant on runoff from the surrounding mountains, oases in the hyperarid Tarim Basin are especially fragile and sensitive to both climatic–environmental changes and human activity. However, the local evolution process of oases in desert area remains unclear due to strong erosion and contemporaneous heterogeneity, which restricts our understanding of the coupling relationship among climate change, oasis evolution, and human activity. Here, we reconstruct the evolution of oases since the last deglacial period (~15 ka) in the Tarim Basin. The results indicate that oases advanced during 15–11.5 ka, 9–4.5 ka, and 2–1 ka. Through the integration of multiple records of palaeoclimate, palaeoenvironment, archaeology and history, we found that human activity dominated and decoupled oasis evolution from climate change since ~2 ka in the Tarim Basin. Oasis were artificially expanded to sustain the flourishing society during the Han–Tang period, but they declined synchronously afterward. More attention should be paid to the proper management of land and water resources to achieve sustainable development in hyperarid areas.
How to cite: Sun, A.: Human activity has decoupled oasis evolution from climate change since ~2 ka in the Tarim Basin, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-10215, https://doi.org/10.5194/egusphere-egu25-10215, 2025.
The Canary Islands, located in the central North Atlantic, provide an exceptional setting for investigating long-term climate dynamics within the Macaronesian region. This study presents sedimentary records from volcanic lacustrine basins across Tenerife, La Gomera and La Palma, analyzed using a multi-proxy approach including magnetic susceptibility, XRF geochemistry, elemental composition (TOC, TN, TS), mineralogy, lipid biomarkers, and updated age models. Preliminary age models suggest that the sequences of La Vega Lagunera (northern Tenerife) extend back up to 400,000 years, and El Malpaís de La Rasca (southern Tenerife), Garajonay (La Gomera), and Playa de Taburiente (La Palma) span the Holocene.
Preliminary results from La Vega Lagunera, a Pleistocene clastic lake, indicate colder conditions during MIS 2 and MIS 4, warmer conditions during the Holocene, MIS 3, and MIS 5, and millennial-scale cycles during MIS 3 and MIS 4. Climate during the Last Glacial Maximum (MIS 2) was notably drier, resembling mid-latitude records.
Holocene records from paleolacustrine deposits of two closed-drainage basins located in two volcanic craters (La Gomera and Malpaís de La Rasca) and the lacustrine-marsh system of Playa de Taburiente showed coherent patterns of Holocene regional climate variability, with increased fluvial and alluvial activity during the Greenlandian (11.7 to 8.2 ka), a decline during the Northgrippian (8.2 to 4.2 ka), and reduced clastic input during the Meghalayan (last ~4.2 ka). These trends suggest increasing aridity throughout the Holocene.
These new sedimentary sequences from Tenerife, La Gomera, and La Palma provide further evidence of rapid climate dynamics during glacial and interglacial intervals. Improved age models (OSL, 14C) are still being developed to characterize the cyclic patterns better, while multi-proxy analyses are enhancing our understanding of past climate dynamics. Further research is needed to clarify the roles of regional climate and local factors.
This work is supported by TED2021-129695A-I00 project funded by MICIU/AEI/10.13039/501100011033 and by the European Union NextGenerationEU/PRTR; PALEOMOL (2915/2022) and IVRIPARC (2779/2021), both funded by the Spanish National Parks Organism, and IMPACT (2022CLISA04, Fundación CajaCanarias and Fundación La Caixa).
How to cite: Ocón-Bermúdez, C., Galofre-Penacho, M., Valero-Garcés, B., Armenteros-Armenteros, I., Herrera-Herrera, A., Égüez, N., Martín-Luis, M. C., Casillas Ruiz, R., Vegas, J., Castellano-Rotger, L., Diez-Herrero, A., Casado-Vara, R., and Jambrina-Enríquez, M.: A Multi-Proxy Approach to Reconstructing Long-Term Climate and Environmental Dynamics in the Canary Islands: Inter-Island Comparisons, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-12407, https://doi.org/10.5194/egusphere-egu25-12407, 2025.
The unique mass-occurrence of tiny heteromorph ammonites found in a single layer in the Mt. Cipollara locality of Cerreto d'Esi (Maiolica Formation, Umbro-Marchean Basin, Italy) provides critical insights into the depositional environments of the Cretaceous upper Maiolica Formation. The mechanisms behind the formation and preservation of these ammonite assemblages within black shales remain poorly understood. To solve this knowledge gap, we constrained by means of biostratigraphy and stable Carbon isotopes the whole sections hosting the ammonites-rich layer. The latter was then subjected a high-resolution paleoecological analyses. Samples were collected systematically across multiple stratigraphic levels to ensure comprehensive coverage. The ammonite assemblages were documented, focusing on their morphology, abundance, and associated sedimentary structures. Additionally, sedimentological petrographic examinations were conducted to elucidate depositional processes. Our results reveal a rich assemblage dominated by the family Leptoceratoididae, exhibiting relatively good preservation within a predominantly dysoxic low-energy environment at the bottom. Calcareous nannofossils data suggest the presence of a well-stratified water column, with a low salinity water cap. The multidisciplinary analyses indicates that these black shales served not only as a repository for ammonite remains but also reflected localized paleoecological conditions characterized by reduced turbulence and increased organic deposition. This unique sedimentary context suggests that the deposition of these assemblages could have been influenced by both regional sea-level fluctuations and local hydrographic conditions. In conclusion, the study of the Mt. Cipollara heteromorph ammonites underscores the complexity of Cretaceous paleoenvironments and provides an enhanced understanding of the occurrence of black shales within the Maiolica Formation.
How to cite: Conti, C., Faraoni, P., Mancini, A. M., Luca, M., and Negri, A.: Unusual mass-occurrence of small, uncoiled ammonites in a black shale of the Maiolica Formation in the Umbria-Marche Basin (Central Italy), EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-3477, https://doi.org/10.5194/egusphere-egu25-3477, 2025.
The Pliensbachian/Toarcian event (P/T-E) and the Toarcian Oceanic Anoxic Event (T-OAE) are two intervals of carbon cycle perturbations linked to massive 12C-enriched carbon emissions, causing severe biotic and environmental changes. Here organic carbon isotope, mineralogical composition and sedimentology have been analyzed across the Pliensbachian-Toarcian transition from the Monte Serrone section (Umbria-Marche Basin), which was deposited in a pelagic setting in the western Tethys. A marked negative carbon-isotope excursion occurred across the Pliensbachian-Toarcian boundary and lower Toarcian, respectively, which can be used to identify PTE and T-OAE in the study area. The P/T-E and T-OAE intervals witnessed carbonate production crisis revealed by reduced carbonate contents. We hold that the 0.5 m-thick laminated black shales indicated that the T-OAE was a highly condensed succession because it included the full duration of the T-OAE. Therefore, the T-OAE interval at Monte Serrone coincided not only with diminished carbonate production but also with reduced siliciclastic input, forming quite thin black shale deposition. Abundant marine organisms were present preceding the T-OAE. Nevertheless, none of them survived during the most negative carbon-isotope excursion of the T-OAE, revealing a biotic crisis at this time. Elevated seawater temperature could induce this crisis in the study area. The recovery of benthic foraminifera was delayed at Monte Serrone.
How to cite: Nie, Y., Fu, X., and Rigo, M.: Carbon cycle perturbations during the Pliensbachian-Toarcian transition in the Monte Serrone section (Northern Apennines, Italy), EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-16338, https://doi.org/10.5194/egusphere-egu25-16338, 2025.
While the effects of OAEs are well known for the pelagic successions of the Tethys Ocean, little is known about their impact on the Peri-Tethyan shallow water carbonate systems. Here we present the preliminary results of a study related to the geological mapping of the sheet 390 – Frosinone of the Geological Map of Italy (CARG Project), focussed on the identification and description of the perturbation induced in the Lower Cretaceous shallow water carbonate succession of the Latium-Abruzzi Carbonate Platform by the well-known Early Cretaceous Oceanic Anoxic Events (OAEs).
In the Ernici Mts. (central Apennines, Italy), an Upper Triassic to Upper Cretaceous shallow-water carbonate succession is exposed (Cosentino et al., 2010; Fabbi et al., 2023). This study specifically examines the Lower Cretaceous "calcari ciclotemici a gasteropodi" fm. (CCG - Berriasian p.p. - lower Aptian p.p.), which mainly consists of whitish limestones with intercalations of light grey dolostones. Within this succession, a layer of black dolostone, about ten centimetres thick, has been observed in several outcrops of the dolomitic lithofacies (CCGa) of CCG, at the same stratigraphic position.
Two stratigraphic sections were measured to characterise the microfacies and compositional variations observed between the light-coloured (whitish to light grey) and black layers. SEM images, along with Energy-Dispersive X-ray Spectroscopy (EDS) and Wavelength-Dispersive X-ray Spectroscopy (WDS) analysis indicated the presence of siderite and pyrite aggregates (Meng et al. 2024). These aggregates appear in high concentration starting from the basal part of the blackish dolostone layer and gently decrease towards the upper part of the study interval. TOC and sulphates show similar trends.
Changes in chemical composition between the whitish and blackish dolostones (CCGa) were investigated in situ using the laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) facility at Roma Tre University. The results show a significant increase in elemental concentration of P, Fe, Zn, As, Ba, Pb, and U, as well as in the Fe/Al ratio in the blackish dolostones. These elements are generally considered as redox-sensitive proxies associated with anoxic paleoenvironments (Bodin et al., 2007; Craigie, 2018).
Biostratigraphic calibration performed on the collected samples has established a Hauterivian p.p. age for the investigated CCGa levels. A preliminary attempt for U-Pb dating of the CCGa black dolostone was carried out through LA-ICP-MS investigations at Roma Tre and ETH facilities. In the Tera-Wasserburg diagram, the U-Pb measurements on CCGa black dolostone yielded a lower intercept age of 125.7± 1.8 Ma (MSWD=1.6; N=19). These promising results suggest that the changes in the elemental concentration of the redox-sensitive proxies observed in the CCGa black dolostone were induced by the late Hauterivian Faraoni Oceanic Anoxic Event.
How to cite: Artegiani, F., Cipollari, P., Cosentino, D., Rabiee, A., Guillong, M., Rossetti, F., Cipriani, A., and Fabbi, S.: Early Cretaceous Oceanic Anoxic Events (OAEs) in Peri-Tethyan shallow-water carbonate systems: Evidence from the Latium-Abruzzi Carbonate Platform (Ernici Mts, Central Italy), EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-11624, https://doi.org/10.5194/egusphere-egu25-11624, 2025.
Human-induced carbon emissions are altering the modern climate, with severe repercussions on ecosystems. Among others, anthropogenic pressure is causing deoxygenation of the bottom water, with the widespread establishment of hypoxic zones in several Mediterranean areas. The geological archives allow the investigation of past deoxygenation dynamics (sapropel events) and their impact on marine ecosystems. Here, we compare the causes and the evolution of deoxygenation dynamics that occurred during two different time periods (Messinian and Holocene) in different paleoceanographic settings based on their micropaleontological content. The Messinian sapropel events are the result of increased export productivity during a relatively cold and arid context, triggering bottom anoxic conditions. The Holocene sapropel formed in response to weakening/stopping of the thermohaline circulation due to increasing temperature and freshwater input. Our results suggest that the deoxygenation dynamics in the Mediterranean in the near future will not follow the trend characteristic of the Holocene deep-sea sapropel because of the predicted drying trend. Differently, the paleoceanographic setting triggering the Messinian shallow-sea sapropels is comparable with the modern situation in different Mediterranean areas, where human-induced eutrophication is promoting deoxygenation. Based on these results, we suggest that the patchy deoxygenation trend in the Mediterranean Sea caused by climate warming may lead to a drastic change in the ecosystem services which would likely impact human activities.
How to cite: Lozar, F., Mancini, A. M., Morigi, C., Gennari, R., and Negri, A.: Past analogues of deoxygenation events in the Mediterranean Sea: Comparison between shallow and deep settings , EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-15403, https://doi.org/10.5194/egusphere-egu25-15403, 2025.
The Lagoa Real uranium province (LRUP) is the main Brazilian target for uranium. Their geochronological studies began in the 80s and provided controversial ages for mineralization. Since then, advances in geochronological methods, increased local petrological data, and knowledge of the uranium cycle have helped geosciences understand crust and mantle behavior over time. As a result, recent geochronological studies developed by CDTN researchers have now begun to reinterpret the evolution of the LRUP.
These studies dated metasomatic U-ore bodies providing ages between 545 Ma to 520 Ma (in situ U–Pb dating of andradite and titanite, Santos et al., 2023; Journal of South America Earth Science) coeval with the late Pan-African Cycle. Geochronological studies were also carried out on the host rocks (A-Type granites) of the mineralized bodies, providing ages between 1762 Ma to 1741 Ma (U–Pb dating of magmatic Zircon, Amorim et al., 2022; Journal of South America Earth Science), coeval to bimodal magmatism well documented in Brazil and Africa.
Although some of the data obtained suggest that granites might not be the source of uranium, their volcanic expression (metaryolites located to the NW of the LRUP) could be a good candidate. Thus, the uranium mobilization began before the metasomatism, through magmatic processes, coeval with the Post-Archean Uranium Recycling, a global event that incorporates U in the crust from the mantle. Furthermore, preliminary macroscopic and microscopic data from gneisses show evidence of partial melting related to regional metamorphism that may have occurred before metasomatism. This process generated Neoproterozoic uranium deposits in Namibia, at the Southern of the African counterpart of Brazil. Therefore, LRUP could result from overlapping processes in central Brazil accompanied by crustal differentiation episodes leading to a polycyclic evolution.
How to cite: Azevedo, R. A. and Rios, F. J.: The Lagoa Real Uranium Province: polycyclic evolution in the Brazilian geochronological record, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-19922, https://doi.org/10.5194/egusphere-egu25-19922, 2025.
