Genesis of positive Eu anomalies in acid rocks from the Eastern Baltic Shield

Terekhov, E. N.; Shcherbakova, T. F.

doi:10.1134/s0016702906050028

Cited by 18 publications

(2 citation statements)

References 11 publications

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“…In creased con cen tra tion of Eu in sed i men tary rocks is most of ten in ter preted as in her ited from par ent ig ne ous rocks (Tay lor and McLennan, 1985;Awwiller, 1994;Nyakairu and Koeberl, 2001;McLennan and Tay lor, 2012), mainly acid rocks (Terekhov and Shcherbakova, 2006) which abound in Eu, and this is prob a bly the cause of this anom aly in both gla cial tills.…”

Section: Fig 2 Pass-nor Mal Ized (Tay Lor and Mclennan 1985) Ree Amentioning

confidence: 99%

Rare earth elements (REE) and thorium in the youngest Pleistocene glacial tills in Poland

Kwećko¹

2016

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Kwecko, P., 2016. Rare earth el e ments (REE) and tho rium in the youn gest Pleis to cene gla cial tills in Po land. Geo log i cal Quar terly, 60 (2): 451-460, doi: 10.7306/gq.1295The study en com passed out crops of gla cial tills (top soil, sub soil-1, sub soil-2) of the max i mum stadial of the Vistulian Glaci ation and of the Wartanian Stadial of the Odranian Gla ci ation, oc cur ring along the max i mum ex tent of the Vistulian ice sheet. The youn gest Pol ish gla cial tills show very sim i lar con cen tra tions of REE and Th. The con cen tra tions of these el ements vary across a wide range from 0.08 mg/kg (Tm and Lu) to 70.3 mg/kg (Ce), with slightly higher val ues for the older tills (Wartanian). Both these tills show clear frac tion ation of LREE and HREE, with a higher and more var ied LREE con centra tion. The most prom i nent fea ture dis tin guish ing one till from the other is the dis tri bu tion of REE frac tions along their verti cal sec tions. In the youn ger (Vistulian) tills the max i mum con cen tra tion of in di vid ual LREE is found at a depth of 1.0 m, and of HREE, Sc and Th, at 2.0 m; while in the older (Wartanian) tills the high est con cen tra tions of all el e ments in ves tigated are ob served at a depth of 1.0 m. Also, the min eral com po si tions of the tills are very alike. The dom i nant min er als are quartz (av er age 56%) and feld spars (ap prox i mately 9%), with a trend of de creas ing con cen tra tions with depth. There are no car bon ates in the top soil (0.3 m level), and the clay min er als are dom i nated by illite (ap prox i mately 16%) and kaolinite (av er age 5%). Sta tis ti cal anal y sis in di cates over a dozen fac tors de ter min ing the con cen tra tion of REE and Th in both tills. Three of them have a cru cial (96% of to tal vari a tion) ef fect on the con cen tra tions of these el e ments. These fac tors are prob a bly of geogenic na ture, in ti mately as so ci ated with sim i lar source ar eas, and with sim i lar pro cesses of de po si tion, diagenesis and weath er ing of the tills.

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Section: Fig 2 Pass-nor Mal Ized (Tay Lor and Mclennan 1985) Ree Amentioning

confidence: 99%

Rare earth elements (REE) and thorium in the youngest Pleistocene glacial tills in Poland

Kwećko¹

2016

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“…То же самое наблюдается и для эклогитоподобных пород, поднятых в виде отдельных блоков в корневой части рифтовых систем [Terekhov et al, 2016]. Устойчивые положительные Eu-аномалии характерны для анортозитов, которые занимают небольшие объемы в гранулитовых комплексах, а также в жильных образованиях заключительного этапа эксгумации этих комплексов [Terekhov, Shcherbakova, 2006]. Кроме них среди коровых комплексов положительную Еu-аномалию имеют нефть, некоторые угли и отчасти фосфориты, т.е.…”

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Geochemical Markers of the Joint Structural and Compositional Evolution of the Basement and Cover (Northern Ladoga Swecofennides, Russia)

Morozov

Terekhov

Matveev

et al. 2022

Geodin. tektonofiz.

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Detailed studies of the deeply metamorphosed Early Precambrian rocks of the Northern Ladoga region allowed us to distinguish three deformation stages of the Svecofennian tectogenesis during which there occurred significant structural and compositional transformations of the "cover (Paleoproterozoic) – basement (Archean)" system. In addition to the structural-paragenetic analysis, which allowed to allocate transversal structural paragenesis in both floors, there are some other opportunities in the recognition of their-hosted granitoid veined bodies with a positive Eu anomaly. The rock varieties with this anomaly are always high in barium and do not show a direct correlation between the Eu anomaly and (La/Yb)n, Ca and Sr. This is contrary to the ideas about the occurrence of a positive Eu anomaly due to the substitution of divalent strontium by Eu++ and suggests that the formation of such rocks took place under the influence of deep reduced fluids. It was found that granitoids with a positive Eu anomaly were formed during the first and last stages of the structure evolution, with a predominance of brittle deformations and a deep-reduced fluid breakthrough. At the second stage, with the dominant manifestation of plastic deformations, when such fluids could be "blocked" within the system, there was a formation of granitoids with low barium concentrations and a negative Eu anomaly.

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Mineral chemistry of the Geyer SW tin skarn deposit: understanding variable fluid/rock ratios and metal fluxes

Meyer,

Burisch,

Gutzmer

et al. 2024

Miner Deposita

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The Geyer tin skarn in the Erzgebirge, Germany, comprises an early skarnoid stage (stage I, ~ 320 Ma) and a younger metasomatic stage (stage II, ~ 305 Ma), but yet, the source and distribution of Sn and the physicochemical conditions of skarn alteration were not constrained. Our results illustrate that contact metamorphic skarnoids of stage I contain only little Sn. REE patterns and elevated concentrations of HFSE indicate that garnet, titanite and vesuvianite of stage I formed under rock-buffered conditions (low fluid/rock ratios). Prograde assemblages of stage II, in contrast, contain two generations of stanniferous garnet, titanite-malayaite and vesuvianite. Oscillation between rock-buffered and fluid-buffered conditions are marked by variable concentrations of HFSE, W, In, and Sn in metasomatic garnet. Trace and REE element signatures of minerals formed under high fluid/rock ratios appear to mimic the signature of the magmatic-hydrothermal fluid which gave rise to metasomatic skarn alteration. Concomitantly with lower fluid-rock ratio, tin was remobilized from Sn-rich silicates and re-precipitated as malayaite. Ingress of meteoric water and decreasing temperatures towards the end of stage II led to the formation of cassiterite, low-Sn amphibole, chlorite, and sulfide minerals. Minor and trace element compositions of cassiterite do not show much variation, even if host rock and gangue minerals vary significantly, suggesting a predominance of a magmatic-hydrothermal fluid and high fluid/rock ratios. The mineral chemistry of major skarn-forming minerals, hence, records the change in the fluid/rock ratio, and the arrival, distribution, and remobilization of tin by magmatic fluids in polyphase tin skarn systems.

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Genesis of positive Eu anomalies in acid rocks from the Eastern Baltic Shield

Cited by 18 publications

References 11 publications

Rare earth elements (REE) and thorium in the youngest Pleistocene glacial tills in Poland

Rare earth elements (REE) and thorium in the youngest Pleistocene glacial tills in Poland

Geochemical Markers of the Joint Structural and Compositional Evolution of the Basement and Cover (Northern Ladoga Swecofennides, Russia)

Mineral chemistry of the Geyer SW tin skarn deposit: understanding variable fluid/rock ratios and metal fluxes

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