The composition and evolution of the continental crust: rare earth element evidence from sedimentary rocks

1981 ◽  
Vol 301 (1461) ◽  
pp. 381-399 ◽  
Keyword(s):  
Rare Earth ◽  
Partial Melting ◽  
Continental Crust ◽  
Rare Earth Element ◽  
Lower Crust ◽  
Sedimentary Rock ◽  
Earth Element ◽  
Upper Crust ◽  
Crustal Composition ◽  
Eu Anomaly

The composition of the present-day upper crust, inferred from the uniformity of sedimentary rock r.e.e. (rare earth element) patterns, is close to that of granodiorite. A revised ‘andesite’ model is used to obtain total crustal composition. The lower crust is the composition remaining, assuming that the upper crust, one-third of the total, is derived from intracrustal partial melting. The upper-crustal r.e.e. pattern has pronounced Eu depletion (Eu/Eu* = 0.64), the lower-crustal pattern has Eu enrichment (Eu/Eu* = 1.17) and the total crust has no Eu anomaly relative to chondritic abundances. The Eu depletion in the upper crust is attributed to retention of Eu in plagioclase in the lower crust. Because plagioclase is not stable below 40 km (> 10 kbar), the anomaly is intracrustal in origin. The Archaean upper crust has a different r.e.e. pattern to that of the present-day upper crust, being lower in total r.e.e., and La/Yb ratios, and lacking an Eu anomaly. These data are used to infer the Archaean upper-crustal composition, which resembles that of the present-day total crust, except that Ni and Cr contents are higher. The Archaean crustal composition can be modelled by a mixture of tholeiites and tonalite trondhjemites. The latter have steep light r.e.e.-enriched-heavy r.e.e.-depleted patterns, consistent with equilibration with garnet and hence probable mantle derivation. There is little reason to suppose that the Archaean lower crust was different in composition from the upper crust, except locally where partial melting episodes occurred. The r.e.e. evidence is consistent with isotopic and geological evidence for a low continental growth rate in the early Archaean, a massive increase (to about 70% of the total crust) between about 3000 and 2500 Ma B.P. and a slow increase until the present day. The change from Archaean to post-Archaean r.e.e. patterns in the upper crust is not isochronous, but is reflected in the sedimentary rock r.e.e. patterns at differing times in different continents. On the basis of a model composition for the mantle, 36% of the potassium, 30% of uranium, 15% of lanthanum and 3 % of ytterbium are concentrated in the present continental crust. This enrichment is related to ionic size and valency differences from common mantle cations (e.g. Mg, Fe). Pre-3.9 Ga B.P. crusts were obliterated by meteorite bombardment. No geochemical evidence exists for primordial anorthositic, sialic or mafic crusts.

Petrogenesis and tectonic setting of the Dapingliang Late Neoproterozoic magmatic rocks in the eastern Kuluketage Block: geochronological, geochemical and Sr–Nd–Pb–Hf isotopic implications

2019 ◽  
Vol 157 (2) ◽  
pp. 173-200
Author(s):  
Wei Chen ◽  
Xinbiao Lü ◽  
Xiaofeng Cao ◽  
Wenjia Ai
Keyword(s):  
Rare Earth ◽  
Partial Melting ◽  
Rare Earth Element ◽  
Mantle Plume ◽  
Lower Crust ◽  
Earth Element ◽  
Continental Rift ◽  
Isotopic Data ◽  
Magmatic Rocks ◽  
Intrusive Rocks

AbstractIn the past ten years, a great deal of geological study has been reported on the magmatic rocks exposed in the central and western region of the Kuluketage Block, while similar research in the eastern region has rarely been reported. In this paper, we report zircon U–Pb geochronological, zircon Lu–Hf isotopic, whole-rock elemental and Sr–Nd–Pb isotopic data for the Dapingliang intermediate-acid intrusive rocks in the eastern Kuluketage Block, in order to evaluate its petrogenesis and tectonic significance. Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) zircon U–Pb dating provided a weighted mean 206Pb/238U age of 735 ± 3 Ma for the albitophyre (D1), 717 ± 2 Ma for the granite porphyry (D2) and 721 ± 1 Ma for the diorite porphyrite (D3). Geochemical analyses reveal that D1 and D2 belong to Na-rich alkaline A-type granites, and D3 shows the features of high-K calc-alkaline I-type granite. D1 and D2 are characterized by light rare earth element (LREE) enrichment and relative depletion of high field strength element (HFSE), with relatively flat heavy rare earth element (HREE) patterns and obviously negative Eu anomalies. D3 is characterized by the enrichment of LREE and depletion of HFSE, with negative slope HREE patterns and slightly negative Eu anomalies. In tectonic discrimination diagrams, D1 and D2 fall in the within-plate granite (WPG) field, indicating a rift setting. Although D3 falls within the volcanic arc granite (VAG) field, it most likely formed in a rift setting, as inferred from its petrology, Sr–Nd–Hf isotopes and regional tectonic evolution. Based on pronounced εNd(t), εHf(t), Pb isotopic data, TDM2 and high (87Sr/86Sr)i and elemental compositions, D1 was derived from the partial melting of basement amphibolites of the old lower crust. D2 originated from a mixture of the old lower crust and depleted mantle-derived magmas and was dominated by partial melting of the basement amphibolites of the lower crust. D3 could have been formed by partial melting of K-rich hornblende in the lower crust. Combining previous studies, we think that the c. 745–710 Ma magmatic rocks were formed in a continental rift setting. A partial melting scheme, triggered by underplating of mantle plume-derived magmas, is proposed to interpret the formation of c. 745–710 Ma A-type and I-type granitoids, mantle-derived mafic dykes, bimodal intrusive rocks, adakitic granites and volcanic rocks. These magmatic activities were probably a reflection of the break-up of the Rodinia supercontinent.Highlights(1)Circa 720 Ma magmatism in the eastern Kuluketage Block.(2)Na-rich granite was derived from partial melting of basement amphibolites.(3)The c. 745–710 Ma magmatic rocks were formed in a continental rift setting.(4)The underplating of mantle plume-derived magmas is proposed.

Rare earth element patterns of carbonado and yakutite: evidence for their crustal origin

1993 ◽  
Vol 57 (389) ◽  
pp. 607-611 ◽  
Author(s):  
Ken Shibata ◽  
Hikari Kamioka ◽  
Felix V. Kaminsky ◽  
Vassili I. Koptil ◽  
Darcy P. Svisero
Keyword(s):  
Trace Elements ◽  
Rare Earth ◽  
Neutron Activation ◽  
Rare Earth Element ◽  
Earth Element ◽  
Meteorite Impact ◽  
Abundance Patterns ◽  
Eu Anomaly ◽  
Crustal Origin ◽  
Monocrystalline Diamond

AbstractCarbonado and yakutite are both porous aggregates of polycrystalline micrometre-size diamond, with very different characters from those of monocrystalline diamond. The genesis of carbonado is very controversial, whereas yakutite is thought to have been formed by meteorite impact. Neutron activation analyses of trace elements in carbonado and yakutite indicate that their rare earth element (REE) abundance patterns have common characteristics: heavy REEs are not much depleted and a negative Eu anomaly is observed. These patterns are quite different from those of kimberlite and monocrystalline diamond and are similar to those of crustal materials such as shale, supporting the hypothesis of a crustal origin for carbonado and yakutite.

Constraints on partial melting imposed by rare earth element variations in Mauna Kea basalts

1996 ◽  
Vol 101 (B5) ◽  
pp. 11815-11829 ◽  
Author(s):  
Mark D. Feigenson ◽  
Lina C. Patino ◽  
Michael J. Carr
Keyword(s):  
Rare Earth ◽  
Partial Melting ◽  
Rare Earth Element ◽  
Earth Element

scholarly journals SHRIMP U–Pb and REE data pertaining to the origins of xenotime in Belt Supergroup rocks: evidence for ages of deposition, hydrothermal alteration, and metamorphism

2015 ◽  
Vol 52 (9) ◽  
pp. 722-745 ◽  
Author(s):  
John N. Aleinikoff ◽  
Karen Lund ◽  
C. Mark Fanning
Keyword(s):  
Rare Earth ◽  
Rare Earth Element ◽  
Detrital Zircon ◽  
Earth Element ◽  
Greenschist Facies ◽  
Eastern United States ◽  
Burial Diagenesis ◽  
Heavy Rare Earth Element ◽  
Eu Anomaly ◽  
Belt Supergroup

The Belt–Purcell Supergroup, northern Idaho, western Montana, and southern British Columbia, is a thick succession of Mesoproterozoic sedimentary rocks with an age range of about 1470–1400 Ma. Stratigraphic layers within several sedimentary units were sampled to apply the new technique of U–Pb dating of xenotime that sometimes forms as rims on detrital zircon during burial diagenesis; xenotime also can form epitaxial overgrowths on zircon during hydrothermal and metamorphic events. Belt Supergroup units sampled are the Prichard and Revett Formations in the lower Belt, and the McNamara and Garnet Range Formations and Pilcher Quartzite in the upper Belt. Additionally, all samples that yielded xenotime were also processed for detrital zircon to provide maximum age constraints for the time of deposition and information about provenances; the sample of Prichard Formation yielded monazite that was also analyzed. Ten xenotime overgrowths from the Prichard Formation yielded a U–Pb age of 1458 ± 4 Ma. However, because scanning electron microscope – backscattered electrons (SEM–BSE) imagery suggests complications due to possible analysis of multiple age zones, we prefer a slightly older age of 1462 ± 6 Ma derived from the three oldest samples, within error of a previous U–Pb zircon age on the syn-sedimentary Plains sill. We interpret the Prichard xenotime as diagenetic in origin. Monazite from the Prichard Formation, originally thought to be detrital, yielded Cretaceous metamorphic ages. Xenotime from the McNamara and Garnet Range Formations and Pilcher Quartzite formed at about 1160–1050 Ma, several hundred million years after deposition, and probably also experienced Early Cretaceous growth. These xenotime overgrowths are interpreted as metamorphic–diagenetic in origin (i.e., derived during greenschist facies metamorphism elsewhere in the basin, but deposited in sub-greenschist facies rocks). Several xenotime grains are older detrital grains of igneous derivation. A previous study on the Revett Formation at the Spar Lake Ag–Cu deposit provides data for xenotime overgrowths in several ore zones formed by hydrothermal processes; herein, those results are compared with data from newly analyzed diagenetic, metamorphic, and magmatic xenotime overgrowths. The origin of a xenotime overgrowth is reflected in its rare-earth element (REE) pattern. Detrital (i.e., igneous) xenotime has a large negative Eu anomaly and is heavy rare-earth element (HREE)-enriched (similar to REE in igneous zircon). Diagenetic xenotime has a small negative Eu anomaly and flat HREE (Tb to Lu). Hydrothermal xenotime is depleted in light rare-earth element (LREE), has a small negative Eu anomaly, and decreasing HREE. Metamorphic xenotime is very LREE-depleted, has a very small negative Eu anomaly, and is strongly depleted in HREE (from Gd to Lu). Because these characteristics seem to be process related, they may be useful for interpretation of xenotime of unknown origin. The occurrence of 1.16–1.05 Ga metamorphic xenotime, in the apparent absence of pervasive deformation structures, suggests that the heating may be related to poorly understood regional heating due to broad regional underplating of mafic magma. These results may be additional evidence (together with published ages from metamorphic titanite, zircon, monazite, and garnet) for an enigmatic, Grenville-age metamorphic event that is more widely recognized in the southwestern and eastern United States.

scholarly journals Rare Earth Element Geochemistry of the Zigzag - Klondyke Sedimentary Rock Formations: Clues to the Evolution of the Baguio Mineral District (Luzon), Philippines

2005 ◽  
Vol 55 (3) ◽  
pp. 217-224 ◽  
Author(s):  
Tomas A. Tam III ◽  
Graciano P. Yumul ◽  
Estephanie Gera L. Ramos ◽  
Carla B. Dimalanta ◽  
Mei-Fu Zhou ◽  
...  
Keyword(s):  
Rare Earth ◽  
Rare Earth Element ◽  
Sedimentary Rock ◽  
Earth Element ◽  
Element Geochemistry ◽  
Rock Formations ◽  
Mineral District

The tonalite–trondhjemite–granodiorite (TTG) to granodiorite–granite (GG) transition in the late Archean plutonic rocks of the central Wyoming Province

2006 ◽  
Vol 43 (10) ◽  
pp. 1419-1444 ◽  
Author(s):  
Carol D Frost ◽  
B Ronald Frost ◽  
Robert Kirkwood ◽  
Kevin R Chamberlain
Keyword(s):  
Rare Earth ◽  
Continental Crust ◽  
Rare Earth Element ◽  
Earth Element ◽  
Gradual Transition ◽  
Heavy Rare Earth Element ◽  
Isotopic Compositions ◽  
Similar Range ◽  
Wyoming Province ◽  
Ree Patterns

The 2.95–2.82 Ga quartzofeldspathic gneisses and granitoids in the Bighorn, western Owl Creek, and northeastern Wind River uplifts in the central Wyoming Province include low-K tonalite–trondhjemite–granodiorite (TTG) and high-K granodiorite–granite (GG) rocks. Both types of granitoids were intruded contemporaneously, although TTGs are more abundant in the older gneisses. The TTG suite consists of calcic to marginally calc-alkalic rocks that straddle the boundaries between metaluminous and peraluminous and between ferroan and magnesian compositions. Rare-earth element (REE) patterns of these rocks may be highly fractionated with low heavy rare-earth element (HREE) contents and modest to absent Eu anomalies but may also be less strongly HREE depleted. These rocks do not represent first-generation continental crust: most have unradiogenic Nd and radiogenic 207Pb/204Pb isotopic compositions that require the incorporation of isotopically evolved sources. The GG suite has compositions that are transitional between Archean TTG and modern, continental margin calc-alkalic rocks. The GG suite is characterized by higher alkali contents relative to CaO than the TTG suite and higher K/Na ratios but exhibits a similar range in REE patterns. The Nd, Sr, and Pb isotopic compositions of the GG suite are slightly less variable but lie within the range of those of the TTG suite. We interpret them as having a source similar to that of the TTG, perhaps forming by partial melting of preexisting TTG. The shift from TTG-dominated to GG-dominated continental crust was a gradual transition that took place over several hundred million years. Clearly subduction-related calc-alkalic magmatism is not recognized in the Wyoming Province prior to 2.67 Ga.

scholarly journals Vendian and Permian-Triassic plagiogranite magmatism of the Ust’-Belaya Mountains, West-Koryak fold system, Northeastern of Russia

2019 ◽  
pp. 87-114
Author(s):  
A. V. Moiseev ◽  
M. V. Luchitskaya ◽  
I. V. Gul’pa ◽  
V. B. Khubanov ◽  
B. V. Belyatsky
Keyword(s):  
Rare Earth ◽  
Partial Melting ◽  
Rare Earth Element ◽  
Fractional Crystallization ◽  
Earth Element ◽  
Island Arc ◽  
Active Margin ◽  
Fold System ◽  
Icp Ms ◽  
Low K

Vendian and Permian-Triassic plagiogranite magmatism is distinguished for Ust’-Belsky and Algansky terranes of West-Koryak fold system. U–Pb zircon ages from Vendian and Permian-Triassic plagiogranites are 556 ± 3 Ma (SIMS), 538 ± 7 Ma (LA–ICP–MS) and 235 ± 2 Ma (SIMS) consequently. It is revealed, that Vendian and Permian-Triassic plagiogranites are mainly low-K and low-Al. Sr–Nd isotopy and rare-earth element patterns allow supposing their formation by partial melting of primarily mantle substrate or by fractional crystallization of basic magma. Vendian plagiogranites formed within active margin in ensimatic island arc simultaneously with deposition of lower part of volcanic-sedimentary complex of Otrozhninskaya slice. We suggest the Permian-Triassic plagiogranites were being formed within the limits of Ust’-Belsky segment of Koni-Taigonos arc during partial melting of melanocratic ophiolite material build up as fragments in accretionary structure of that arc or by fractional crystallization of basic magmas melted from the similar substrate.

Eu anomaly- reliability of the proxy in inferring source composition of clastic Sedimentary rocks: A case study from western Dharwar craton, Karnataka, India

2020 ◽  
Author(s):  
Anirban Mitra ◽  
Sukanta Dey
Keyword(s):  
Rare Earth ◽  
Rare Earth Element ◽  
Earth Element ◽  
Sedimentary Rocks ◽  
Dharwar Craton ◽  
Source Rocks ◽  
Granitic Rocks ◽  
Negative Anomaly ◽  
Eu Anomaly ◽  
Ree Pattern

<p>Use of trace and rare earth element concentration of terrigenous sedimentary rocks to deduce the composition of their source rocks in the hinterland is a very common and efficient practice. The results of geochemical analysis of the metaquartzarenites located at the basal part of Bababudan and Sigegudda belt, late Archean greenstone sequences of western Dharwar craton show that the sediments were most possibly supplied from Paleo to Mesoarchean granitoids of western Dharwar Craton. Rare earth element patterns of these basal quartzites display fractionated REE pattern in variable degree (La<sub>N</sub>/Yb<sub>N</sub> =1.47-10.63) with moderate to highly fractionated LREE (La<sub>N</sub>/Sm<sub>N</sub>=2.67-8.93) and nearly flat to slighly elevated HREE (Gd<sub>N</sub>/ Yb<sub>N</sub>=0.62-1.29) and a significant Eu negative anomaly (avg. Eu/Eu*=0.67). In general, presence of negative Eu anomaly in clastic rocks reflect the widespread occurrence of granitic rocks in the source area, which possess negative Eu anomaly. On the other hand, mechanical enrichment of zircon (having negative Eu anomaly, high HREE concentration and low La<sub>N</sub>/Yb<sub>N</sub>), if present, will hamper the whole REE pattern of the sediments and necessarily, do not actually mimic the source composition. Here, in our study, the Th/Sc vs Zr/Sc diagram show mineral Zircon has been concentrated by mechanical concentration in the sedimentary rocks. Few quartzite samples which have high Zr content typically exhibit low La<sub>N</sub>/Yb<sub>N</sub> values, reflecting pivotal role of mineral zircon in controlling the REE pattern of the sediments. Hence, in this case, we should be cautious in interpreting of the Eu negative anomaly of the basal quartzites for meticulously identifying their source rock composition. More geochemical and other analytical approaches are required in this regard.</p>

scholarly journals Trace Element and Stable Isotope Geochemistry of Lwamondo and Zebediela Kaolins, Limpopo Province, South Africa: Implication for Paleoenvironmental Reconstruction

Minerals ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 93
Author(s):  
Avhatakali Raphalalani ◽  
Georges-Ivo Ekosse ◽  
John Odiyo ◽  
Jason Ogola ◽  
Nenita Bukalo
Keyword(s):  
Trace Elements ◽  
Rare Earth ◽  
Stable Isotope ◽  
Trace Element ◽  
Continental Crust ◽  
Rare Earth Element ◽  
Earth Element ◽  
Paleoenvironmental Reconstruction ◽  
Δ18o And Δd ◽  
Ree Patterns

The aim of the present study was the paleoenvironmental reconstruction of the prevailing environment under which the Lwamondo and Zebediela kaolin deposits were formed. Hence, this study reports deuterium and oxygen stable isotope values and trace and rare earth element concentrations for two samples of kaolin. Upper continental crust-normalised trace-element patterns reveal that large ion lithophile elements and high-field-strength elements are generally depleted in Lwamondo and Zebediela kaolins, whereas transition trace elements are generally enriched in these kaolins. Upper continental crust-normalised rare earth element (REE) patterns show that there is a slight enrichment of heavy REEs (HREEs) compared to light REEs (LREEs) in these kaolins. The δ18O and δD stable isotope values for kaolinite from Lwamondo ranged from 17.4‰ to 19.1‰ and from −54‰ to 84‰, respectively, whereas those values for kaolinite from Zebediela varied from 15.6‰ to 17.7‰ and from −61‰ to –68‰ for δ18O and δD, respectively. The REE patterns and the content of other trace elements indicate ongoing kaolinitisation in the Lwamondo and Zebediela kaolins with minimum mineral sorting. The sources of the kaolins varied from basic to acidic and these were derived from an active margin tectonic setting. Lwamondo kaolin was deposited in an oxic environment whereas Zebediela kaolin was deposited under suboxic/anoxic conditions. Based on the δ18O and δD values of the kaolinite, they formed in a supergene environment at temperatures generally below 40 °C.

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