Compositionally-Diverse Miocene--Recent Rift-Related Magmatism in Northwest Colorado: Partial Melting, and Mixing of Mafic Magmas from 3 Different Asthenospheric and Lithospheric Mantle Sources

Leat, P. T.; Thompson, R. N.; Morrison, M. A.; Hendry, G. L.; Dickin, A. P.

doi:10.1093/petrology/special_volume.1.351

Cited by 90 publications

(62 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…An enriched asthenospheric source is suggested by the low La/Nb values ( 1.1), in agreement with the hypothesis of Fitton et al (1988) who considered that the basalts of the Basin and Range Province (La/Nb < 1.5 in the OIB range) are of asthenospheric origin and that the basalts from the Sierran Province with La/Nb > 1.5 are from a lithospheric source. The La/Ta ratios shown by the Nurra metagabbro, <14.6 and mostly in the 10-13 range, suggest that they had an asthenospheric source similar to that proposed by Leat et al (1988) for Colorado volcanic rocks characterized by La/Ta < 22. Similarly, Thompson and Morrison (1988) inferred an asthenospheric origin for volcanic rocks of the British Tertiary Province showing La/Ta values in the 10-12 range, and hypothesized contamination by the continental crust or lithospheric mantle for volcanic rocks yielding La/Ta values >30.…”

Section: Evidence Of An Enriched Asthenospheric Mantle Source For Alksupporting

confidence: 68%

Pre‐Variscan metagabbro from NW Sardinia, Italy: evidence of an enriched asthenospheric mantle source for continental alkali basalts

et al. 2003

View full text Add to dashboard Cite

Small metagabbro bodies are enclosed in the metasedimentary sequence of NW Sardinia. The metagabbro represents the last magmatic episode before the continent-continent collision which built up the Variscan chain of north Sardinia.\ud The metagabbro are composed up of variable proportions of plagioclase and pyroxene igneous relics and metamorphic minerals. Major and trace element data, i.e high TiO2, P2O5 and low K, Rb content, as well as LREE, Nb, Ta enrichment, suggest an alkaline affinity for the gabbro and emplacement in a within-plate tectonic setting. The gabbro was derived from an island alkali basalt-like asthenospheric mantle source enriched with incompatible elements and uncontaminated by crustal or subducted materials. Non-modal modelling indicated a 5-7% partial melting of the asthenospheric mantle. \u

show abstract

Section: Evidence Of An Enriched Asthenospheric Mantle Source For Alksupporting

confidence: 68%

Pre‐Variscan metagabbro from NW Sardinia, Italy: evidence of an enriched asthenospheric mantle source for continental alkali basalts

et al. 2003

View full text Add to dashboard Cite

show abstract

“…One includes processes that occur after magma generation (fractional crystallization and/or contamination), whereas the other includes processes that occur during or prior to magma generation (differences in the melting depth, mantle composition, and/or degree of partial melting to form primary magma). Although some workers report crustal contamination in B&R basalts [Walker and Coleman, 1991;Glazner and Farmer, 1992;Yogodzinski et al, 1996], others Kempton et al, 1991;Fraser et al, 1985;Perry et al, 1987;Fitton et al, 1988;Leat et al, 1988;Lum et al, 1989;Reid and Ramos, 1996;Menzies et al, 1983;Beard and Johnson, 1997;DePaolo and Daley, 2000] suggest that in many cases isotopic compositions of continental basalts still reflect variation in the mantle source. Thus isotopic and geochemical compositions of basalts from the B&R have been used to study mantle chemical characteristics [Daley and DePaolo, 1992;Feuerbach et al, 1993;Bradshaw et al, 1993;Farmer et al, 1989Farmer et al, , 1995Rogers et al, 1995;Cooper and Hart, 1990;Livaccari and Perry, 1993;Smith et al, 1999b;Menzies et al, 1985;Ormerod et al, 1991].…”

Section: Major Element Variations In Basalts Across the Basin And Rangementioning

confidence: 99%

A mantle melting profile across the Basin and Range, SW USA

et al. 2002

View full text Add to dashboard Cite

[1] The major and trace element composition of late Cenozoic basalts (0 -10 Ma) across the Basin and Range province (B&R) preserve a clear signal of mantle melting depth variations. FeO, Fe 8.0 , and Tb/Yb increase, whereas Si 8.0 and Al 8.0 decrease, from west to east across the B&R along a profile at 36°-37°N. These variations are qualitatively consistent with shallower melting beneath the Western Great Basin (WGB) than in the central B&R. In order to quantify the depth range and percent of decompression melting, we invert primary Na 2 O and FeO contents of basalts using a melting model based on the partitioning of FeO and MgO in olivine and Na 2 O in clinopyroxene. An independent inversion, using the rare earth elements (REE), corroborates the melting depths obtained from the major element model and places most of the melting beneath the central B&R in the garnet-peridotite stability field. We find that the shape of the melting region across the B&R closely mimics the shape of the mantle lithosphere, as inferred from geological and geophysical observations. Melting across the study area occurs largely within the asthenosphere and generally stops at the base of the mantle lithosphere. In the WGB, melting paths are shallow, from 75 to 50 km, and in some cases extend almost to the base of the crust. These melting paths are consistent with adiabatic melting in normal-temperature asthenosphere, beneath an extensively thinned (or absent) mantle lithosphere. Shallow melting is consistent with geobarometry and isotopic compositions of local mantle xenoliths. Lithospheric thinning was caused by thermal erosion during Mesozoic subduction and/or simple shear or foundering during Cenozoic extension. In contrast, melting beneath the central B&R occurs beneath thick mantle lithosphere and requires mantle potential temperatures 200°C hotter than normal (melting paths from 140 to 100 km). The excess temperature beneath the central B&R is consistent with active upwelling of hot mantle in this region.

show abstract

“…As razões La/Nb indicam valores médios de 4,7 para a associação baixo-Nb e em torno de 2,2 para diabásios alto-Nb. Fitton et al (1988) e Leat et al (1988) sugerem que magmas com altas razões La/Nb (>1,5) podem estar relacionados a fontes de manto litosférico subcontinental. Thompson & Morrinson (1988) sugerem que basaltos toleíticos com baixos conteúdos de Nb em relação à ETRL podem estar relacionados a fontes de manto litosférico modificado por subducção.…”

Section: Tabela 5 -Análises Representativas De óXidos De Fe-ti Da Forunclassified

Litoquímica e química mineral da Formação Quarenta Ilhas no Distrito Mineiro de Pitinga (AM)

Pierosan

Lima

Campos

et al. 2010

RBG

View full text Add to dashboard Cite

Resumo A Formação Quarenta Ilhas consiste de rochas subvulcânicas básicas a intermediárias, de afinidade toleítica e idade em torno de 1,78Ga. A mineralogia magmática é constituída por olivina, substituída pseudomorficamente por ferro-saponita, plagioclásio variando de labradorita a oligoclásio (An 65 Ab 35 a An 20 Ab 80 ), óxidos de Fe-Ti (Ilm 87-95 e Usp 22-37 ), diopsídio a augita (Wo En 44-21 Fs 38-16 ), com ferro-hornblenda (textura coronítica), feldspato alcalino e quartzo nos termos mais diferenciados. Dados petrográficos e litoquímicos apontam para uma evolução por cristalização fracionada de diabásio/gabro até quartzo dioritos, compatível com fracionamento de olivina+ilmenita, magnetita+plagioclásio+augita, e cristalização de ferro-hornblenda, feldspato alcalino e quartzo em estágios tardios. A afinidade com magmas subalcalinos toleíticos é indicada pelos padrões de elementos maiores, proporções de minerais normativos (olivina+hiperstênio e quartzo+hiperstênio) e pelas elevadas razões Y/Nb e La/Yb. Os elevados conteúdos de Cs, Rb, Ba e K, e baixos de Nb, Ta e Zr indicam participação de manto litosférico enriquecido em LILE e previamente modificado por subducção. O padrão de ETR é marcado por enriquecimento de ETRL em relação aos ETRP, o que sugere uma fonte com composição compatível com um granada lherzolito. O posicionamento dos corpos subvulcânicos da Formação Quarenta Ilhas, num ambiente francamente intracratônico, foi precedido pelas atividades orogenéticas relacionadas ao Ciclo Transamazônico (~2,0Ga), pelo magmatismo pós-colisional Uatumã (~1,88Ga) e pelo magmatismo anorogênico da Suíte Madeira (~1,83Ga), num ambiente francamente intracratônico. Palavras-chave:Craton Amazônico, Pitinga, geoquímica, química mineral, magmatismo toleítico. Fs 38-16 ), with ferro-hornblende (as coronitic texture), alkali-feldspar and quartz in the most differentiated rocks. Petrographic and geochemical data point to an evolution through fractional crystallization from diabase/gabbro to quartz diorite, with fractionation of olivine+ilmenita, magnetite+plagioclase+augite, and crystallization of ferro-hornblende, alkali-feldspar and quartz in the later stages. The affinity with tholeiitic subalkaline magma is indicated by features of major elements, normative minerals (olivine+hypersthene and quartz+hypersthene) and high Y/Nb and La/Yb ratios. High Cs, Rb, Ba and K, and low Nb, Ta and Zr, suggest a lithospheric mantle source, enriched in LILE and depleted by subduction. The REE pattern is LREE enriched faced to HREE, that suggest a source of garnet lherzolitic composition. The emplacement of the Quarenta Ilhas subvolcanic bodies follow the orogenetic activity of the Transamazonian Cycle (~2.0Ga), the post-collisional Uatumã magmatismo (~1.88Ga) and the anorogenic magmatism of the Madeira Suite (~1.83Ga), in a fully intracratonic setting. Abstract Lithochemistry and mineral chemistry of Quarenta Ilhas Formation in the Pitinga

show abstract

Compositionally-Diverse Miocene--Recent Rift-Related Magmatism in Northwest Colorado: Partial Melting, and Mixing of Mafic Magmas from 3 Different Asthenospheric and Lithospheric Mantle Sources

Cited by 90 publications

References 0 publications

Pre‐Variscan metagabbro from NW Sardinia, Italy: evidence of an enriched asthenospheric mantle source for continental alkali basalts

Pre‐Variscan metagabbro from NW Sardinia, Italy: evidence of an enriched asthenospheric mantle source for continental alkali basalts

A mantle melting profile across the Basin and Range, SW USA

Litoquímica e química mineral da Formação Quarenta Ilhas no Distrito Mineiro de Pitinga (AM)

Contact Info

Product

Resources

About