scispace - formally typeset
Search or ask a question
Topic

Incompatible element

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


Papers
More filters
01 Jan 1998
TL;DR: In this article, a transect of the SE Greenland seaward-dipping reflector sequence (SDRS) was used to identify two distinct crustal contaminants: lower crustal basic granulite with unradiogenic Nd, Sr, and Pb; and upper crustal amphibolite-facies gneiss with high 208 Pb/ 204 Pb.
Abstract: The southeast Greenland seaward-dipping reflector sequence (SDRS) is composed of Paleocene to Eocene volcanic rocks erupted during continental breakup. Volcanic rocks recovered from a transect across the SDRS at 63°N, during Ocean Drilling Program Leg 152, range in composition from picrite to dacite and represent all the magmatic phases in the development of the continental margin. The earliest magmas, represented by the pre-breakup succession at Site 917 (Lower and Middle Series), were strongly contaminated with continental crust, but the degree of contamination declined rapidly during the late stages of breakup (Site 917 Upper Series). Very low concentrations of incompatible elements in the uncontaminated primitive magmas made them extremely sensitive to the isotopic effects of crustal contamination. Basaltic rocks from the most seaward part of th e transect (Site 918) were erupted after breakup and show no signs of contamination with continental crust. Two distinct crustal contaminants can be recognized: (1) lower crustal basic granulite with unradiogenic Nd, Sr, and Pb; and (2) upper crustal amphibolite-facies gneiss with unradiogenic Nd but highly radiogenic Sr and high 208 Pb/ 204 Pb. The first contaminant affected only the earliest magmas, represented by the lower volcanic units in the Lower Series at Site 917. Later continental magmas were affected by the second contaminant, suggesting storage of magmas at progressively shallower levels in the crust as lithospheric extension proceeded toward continental breakup. The nature and degree of contamination are strikingly similar to those observed in the Hebridean Tertiary igneous province, which would have been adjacent to southeast Greenland during continental breakup.

25 citations

Journal ArticleDOI
TL;DR: In this paper, the effect of sulfur dissolved as sulfide (S2−) in silicate melts on the activity coefficients of NiO and some other oxides of divalent cations (Ca, Cr, Mn, Fe and Co) has been determined from olivine/melt partitioning experiments at 1400°C in six melt compositions in the system CaO-MgO-Al2O3-SiO2 (CMAS), and in derivatives of these compositions at 1370°C, obtained from the six CMAS compositions by substituting Fe for M

25 citations

Journal ArticleDOI
TL;DR: The Hayachine-Miyamori (HM) ophiolitic complex in the Kitakami Mountains, northeastern Japan consists of ultramafic tectonite and cumulate members.

25 citations

Journal ArticleDOI
TL;DR: In this paper, four basalt sections in Jining province, the Baiyinxiang, Hanqingba, Xin’anzhan, and Chahanmiao sections, were analyzed for isotopic compositions.

25 citations

01 Dec 2008
TL;DR: In this article, a melting model for heterogeneous mantle sources is presented that investigates how and to what extent isotope and trace element signatures are conveyed from source to melt, which can be used to deduce the origin of mantle heterogeneity.
Abstract: Numerous isotope and trace element studies of mantle rocks and oceanic basalts show that the Earth’s mantle is heterogeneous. The isotopic variability in oceanic basalts indicates that most mantle sources consist of complex assemblages of two or more components with isolated long-term chemical evolution, on both global and local scales. The range in isotope and highly incompatible element ratios observed in oceanic basalts is commonly assumed to directly reflect that of their mantle sources. Accordingly, the end-points of isotope arrays are taken to represent the isotopic composition of the different components in the underlying mantle, which is then used to deduce the origin of mantle heterogeneity. Here, a melting model for heterogeneous mantle sources is presented that investigates how and to what extent isotope and trace element signatures are conveyed from source to melt. We model melting of a pyroxenite–bearing peridotite using recent experimental constrains for melting and partitioning of pyroxenite and peridotite. Identification of specific pyroxenite melting signatures allows finger-printing of pyroxenite melts and confirm the importance of lithological heterogeneity in the Earth’s mantle. The model results and the comparison of the calculated and observed trace element–isotope systematics in selected MORB and OIB suites (e.g. from the East Pacific Rise, Iceland, Tristan da Cunha, Gough and St.Helena) further show that factors such as the relative abundance of different source components, their difference in solidus temperature, and especially the extent, style and depth range of melt aggregation fundamentally influence the relationship between key trace element and isotope ratios (e.g. Ba/Th, La/Nb, Sr/Nd, La/Sm, Sm/Yb, 143Nd/144Nd). The reason for this is that any heterogeneity present in the mantle is averaged or, depending on the effectiveness of the melt mixing process, even homogenized during melting and melt extraction. Hence to what degree mantle heterogeneity is reflected in the erupted melts is not only a function of source and melting-induced variability. It also depends on the extent of mixing during melting and melt extraction and thus strongly on the relative incompatibility of the elements considered. The observed trace element variation in erupted melts can be greater or smaller than that of their mantle sources, depending on the incompatibility of the elements investigated. The isotopic variability in erupted melts, on the other hand, is generally smaller than that of their mantle source. Melt mixing during melt extraction consequently has an important influence on the relative extent of variation, and hence the degree of correlation between the isotope and trace element ratios. Overall fewer correlations between trace element and isotope ratios are expected whenever melts are extracted from a restricted depth range, as is the case for ocean island basalts, than for cases where melts are extracted over a larger depth interval (mid ocean ridges and especially ridge centered hotspots like Iceland). While the isotopic composition of the most enriched melts may correspond closely to those of the enriched source component, even the most depleted mid ocean ridge basalts are likely to underestimate the isotopic depletion of the depleted mantle component. These observations imply that using the chemical and isotopic range observed in oceanic basalts as directly representative of that in the corresponding mantle source can be misleading, since this assumption is strictly true only for homogeneous mantle sources. In addition to identifying source or partitioning-related differences in melts from different mantle sources, inferring the true composition, origin, and distribution of heterogeneous components in the Earth’s mantle therefore requires detailed knowledge about the mechanisms of melting and melt mixing during the melt extraction process. Only if these processes and their influence on the isotope–trace element relationship are understood, can the composition and origin of the different source components, and thus mantle heterogeneity, be accurately constrained.

25 citations


Network Information
Related Topics (5)
Metamorphism
18.3K papers, 655.8K citations
94% related
Continental crust
11.1K papers, 677.5K citations
94% related
Basalt
18.6K papers, 805.1K citations
93% related
Mantle (geology)
26.1K papers, 1.3M citations
92% related
Zircon
23.7K papers, 786.6K citations
92% related
Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20237
202216
202157
202056
201960
201851