Incompatible element

About: Incompatible element is a research topic. Over the lifetime, 2420 publications have been published within this topic receiving 154052 citations.

Comparative Characteristics of Middle Paleozoic and Late Riphean Plume Magmatism of the Siberian Platform

Abstract: Based on isotopic and geochemical data for Late Riphean dikes and sills and for Devonian dolerite dikes and basalt covers within the Sette-Daban rift in the western part of the Siberian platform, we proved conceptions about the participation of various deep sources in their formation. The inverse correlation in Devonian basites between concentrations of Nb, light rare earth elements, and a number of other highly incompatible elements on the one hand and Zr, Y, and other moderate incompatible elements, including heavy rare earth elements on the other hand allows us to assume that two sources participated in the formation of melts. The source of dolerites is close to the EMORB type, and the source of basalts is close to the OIB type. The compositions of Riphean rocks correspond to a trend for which magma formation occurred with the participation of a source with characteristics between NMORB and EMORB and also a component typical of subduction zones. The data obtained imply associate formation of basites with the influence of mantle plumes on the lithosphere of the southeastern part of the Siberian craton in the Late Riphean and Middle Paleozoic. In the Riphean the plume mantle was composed of a moderately depleted mantle of the EMODB type and a mantle with the composition close to the above-subduction mantle, which was metosomatically changed under the influence of fluid water, which caused the appearance of a Nb and Ta deficit in melting products. The isotopic characteristics Nd(147Sm/144Nd = 0.165 and ɛNd(T) ∼ 2.3–4.7) of rocks show the moderate depleted nature of these sources.

Preliminary study on K-Ar chronology, petrology and geochemistry of Yandunling volcanic rocks, Hepu county, Guangxi

Abstract: Yandunling volcano,which is located in Hepu county,the Guangxi Zhuang Autonomous Region,is a small volcano with central eruption style in the Quaternary Period.Its eruption represents the volcanic activity in south China in Quaternary.The products of Yandunling volcano are trachybasah.Mg~# values(59～69)are from middle to high,and titanium and alkali are comparatively high. The chondrite-normalized abundances of REE diagrams of Yandunling and its neighbour Yantouling volcanic rocks are quite similar and the curves are almost overlapped.The curves show a little steep tilt to HREE,which belongs to LREE-enriched type.The primitive- mantle normalized trace element abundance curves are also similar,indicating they have the same magma source.The variations of Ba/ Nb ratios of Yandunling volcanic rocks are smaller than those from north Hainan and Weizhou Islands,but La/Nb ratios are low and stable which are similar to those from OIB.The plot of incompatible elements of Nb/U and Th also shows that the rocks come from a magma source similar to OIB.The evidences from petrology and geochemistry suggest that the volcanic rocks in Yandunling are little evolved magma rather than primitive basalt from mantle source and they weren't affected by crystal differentiation,were they contaminated by crustal materials.These rocks have similar ~(87)Sr/~(86)Sr and ~(143)Nd/~(144)Nd ratios.The volcanic activities could be dated back to early Pleistocene according to K-Ar dating combined with geological characteristics of volcanic rocks and previous works,which correspond to early volcanic activities of Weizhou Island in Beibu Bay and Duowenling period of volcanic activities in north Haina Island.

Petrology and Geochemistry of Kimberlite Pipe 11 of Chigicherla Area, Anantapur District, Andhra Pradesh, South India

Abstract: Newly discovered kimberlite pipe 11 of Chigicherla area of Andhra Pradesh consists of two generations of olivine with phlogopite, spinel. perovskite, melilite etc., A comparative study of chemical characterstics of pipe 11 with those of pipe 1,2,3,4 and 5 of Wajrakarur- Lattavaram area and pipe 10 of Chighicherla indicate that Zr-Hf, Nb-Ta, Th-U have a high degree of correlation. The ratio of Ba/Nb( 0.5) are similar to the Group-I kimberlites. The chondri te normalised REE pattern of pipe 11 is similar to the other kimberlites and shows enrichment in LREE. Spider diagram of incompatible elements indicate similarity with those of many oceanic island alkalic basalts or other types of alkalic intraplate volcanics. They are highly enriched in incompatible elements. Major elements, Ce/Yb and La/Yb ratios suggest that the formation of kimberlite is due to low degree of partial melting of ultrabasic source along with an earlier subducted oceanic lithosphere.

FeO activity and oxygen potential in magnesian magmas

Abstract: An equation for the excess free energy of melts containing all major components is derived from published experimental data on equilibria between silicate liquids with either metallic iron or spinel at controlled oxygen partial pressure. The FeO activities in mafic and ultramafic magmas calculated with this equation were used to develop an oxygen barometer (geoxometer) for the association spinel + melt. Data derived with the application of the geoxometer confirm that meymechite magmas in the Siberian trap province had oxygen fugacities higher than in other magmatic systems. The origin of lower lithospheric domains with elevated redox potential can be explained by the intense diffusion of hydrogen from zones in which water-rich near-solidus melts from asthenospheric sources were emplaced into harzburgites, which had lost water and other incompatible elements in the course of earlier large-scale melting.

Whole-rock geochemistry and Sr-Nd isotopic evidences for sources and processes of granulite formation in Ribeira Belt, Brazil

Abstract: Elemental and Sr-Nd isotopes data on migmatites, granulites and orthogneisses obtained from the central part of Ribeira Belt (SE Brazil) shows that they are LILE-enriched weakly peraluminous granodiorites. Harker trends for TiO2, Al2O3, Fe2O3 , MgO, P2O5, Sr, Zr, Hf, Th, U, REE , LREE/HREE and La/Lu, as well as incompatible element trends of Th-Hf-La suggest that these rocks represent a cogenetic sequence. Similar REE patterns and juxtaposed isotopic values of Nd 575 = -5.4 to -7.3 and Sr/Sr575 = 0.706 to 0.711 for granulites, orthogneisses and migmatites is consistent with hypothesis that these rocks evolved from a relatively homogeneous and enriched common crustal (metasedimentary) protolith. Results suggest that partial melting of meta-sediments formed migmatites and associated granitoid bodies, whereas long-term crustal slow cooling promoted further dehydration (re-melting) that led to development of widespread granulites [1]. Sm-Nd TDM ages span from 2.0 to 1.5 Ga is consistent with Paleoand Mesoproterozoic contributions to the sedimentary pile that was metamorphosed during the assembly of Gondwana. TDM ages and paleogeographic proximity suggest that the Sao Francisco and West Congo Cratons are the most probable sources for these protoliths. Sm-Nd model ages and inherited zircon SHRIMP dating [2] concordance reveals that the protoliths were part of a juvenile crust formed 2.0 to 1.5 Ga ago, whereas the absence of Pan-African TDM ages suggests zircon sedimentary reworking with U-Pb isotopic homogenization of older zircons. This means that during Pan-African times no significant new crust was added, which, combined with the new geochemical model for granulite formation in the studied area, contradicts poliorogenic scenarios formerly proposed for the evolution of Ribeira Belt.