Geochemistry of Cenozoic basaltic and silicic magmas in the central portion of the Loei–Phetchabun volcanic belt, Lop Buri, Thailand

1995 ◽  
Vol 32 (4) ◽  
pp. 393-409 ◽  
Author(s):  
Suporn Intasopa ◽  
Todd Dunn ◽  
Richard StJ. Lambert
Keyword(s):  
Trace Element ◽  
Partial Melting ◽  
Mantle Source ◽  
Volcanic Rocks ◽  
Volcanic Belt ◽  
Central Portion ◽  
Alkali Basalts ◽  
Crustal Rocks ◽  
Depleted Mantle ◽  
Silicic Magmas

Cenozoic volcanic rocks outcrop in the central portion of the Loei–Phetchabun volcanic belt in central Thailand in the Lop Buri area. The volcanic rocks range in composition from basalt to high-silica rhyolite. In general, the volcanic rocks decrease in age from south to north. The oldest rocks studied are 55–57 Ma rhyolites that are isotopically and geochemically distinct from younger (13–24 Ma) rhyolites that occur farther north. Intermediate rocks (andesite and dacite) are less voluminous than rhyolite. Basalt occurs in the central and northern parts of the area and ranges in composition from olivine tholeiites to nepheline normative alkali basalts. The isotopic, major, and trace element compositions of the andesites, dacites, and younger rhyolites are consistent with an origin for these rocks by variable degrees of partial melting of metabasaltic crustal rocks, themselves derived from a depleted mantle source at approximately 530 ± 100 Ma. The apparent extent of partial melting of metabasalt increases from rhyolite to andesite. The isotopic and trace element systematics of the basalts are consistent with a refertilized depleted mantle source with characteristics of a mixture of normal mid-ocean ridge basalt source mantle and enriched mantle II type mantle.

Petrogenetic modelling of Quaternary post-collisional volcanism: a case study of central and eastern Anatolia

2004 ◽  
Vol 141 (1) ◽  
pp. 81-98 ◽  
Author(s):  
PINAR ALICI ŞEN ◽  
ABİDİN TEMEL ◽  
ALAIN GOURGAUD
Keyword(s):  
Trace Element ◽  
Mantle Source ◽  
Lithospheric Mantle ◽  
Volcanic Rocks ◽  
Crustal Contamination ◽  
Central Anatolia ◽  
Eastern Anatolia ◽  
Alkali Basalts ◽  
Alkaline Volcanism ◽  
Trace Elemental

Extensive continental collision-related volcanism occurred in Turkey during Neogene–Quaternary times. In central Anatolia, calc-alkaline to alkaline volcanism began in the Middle–Late Miocene. Here we report trace elemental and isotopic data from Quaternary age samples from central and eastern Anatolia. Most mafic lavas from central Anatolia are basalt and basaltic andesite, with lesser amounts of basaltic trachyandesite and andesite. All magma types exhibit enrichment in LILE (Sr, Rb, Ba and Pb) relative to HFSE (Nb, Ta). Trace element patterns are characteristic of continental margin volcanism with high Ba/Nb and Th/Nb ratios. 87Sr/86Sr and 143Nd/144Nd isotopic ratios of central Anatolian lavas range between 0.704105–0.705619 and 0.512604–0.512849, respectively. The Quaternary alkaline volcanism of eastern Anatolia has been closely linked to the collision between the Arabian and Eurasian plates. Karacadaǧ and Tendürek volcanic rocks are represented by alkali basalts and basaltic trachyandesites, respectively. As expected from their alkaline nature, they contain high abundances of LIL elements, but Tendürek lavas also show depletion in Nb and Ta, indicating the role of crustal contamination in the evolution of these magmas. 87Sr/86Sr and 143Nd/144Nd ratios of the Karacadaǧ and Tendürek lavas range from 0.703512 to 0.704466; 0.512742 to 0.512883 and 0.705743 to 0.705889 and 0.512676, respectively. Petrogenetic modelling has been used to constrain source characteristics for the central and eastern Anatolian volcanic rocks. Trace element ratio plots and REE modelling indicate that the central Anatolian volcanism was generated from a lithospheric mantle source that recorded the previous subduction events between Afro-Arabian and Eurasian plates during Eocene to Miocene times. In contrast, The Karacadaǧ alkaline basaltic volcanism on the Arabian foreland is derived from an OIB-like mantle source with limited crustal contamination. Tendürek volcanism, located on thickened crust, north of the Bitlis thrust zone, derived from the lithospheric mantle via small degrees (1.5 %) of partial melting.

Crustal assimilation in the Burnt Lake metavolcanics, Grenville Province, southeastern Ontario, and its tectonic significance

1997 ◽  
Vol 34 (9) ◽  
pp. 1272-1285 ◽  
Author(s):  
T. E. Smith ◽  
P. E. Holm ◽  
N. M. Dennison ◽  
M. J. Harris
Keyword(s):  
Rare Earth ◽  
Trace Element ◽  
Partial Melting ◽  
Continental Crust ◽  
Fractional Crystallization ◽  
Volcanic Rocks ◽  
Lake Area ◽  
Depleted Mantle ◽  
Mafic Magmas ◽  
Back Arc

Three intimately interbedded suites of volcanic rocks are identified geochemically in the Burnt Lake area of the Belmont Domain in the Central Metasedimentary Belt, and their petrogenesis is evaluated. The Burnt Lake back-arc tholeiitic suite comprises basalts similar in trace element signature to tholeiitic basalts emplaced in back-arc basins formed in continental crust. The Burnt Lake continental tholeiitic suite comprises basalts and andésites similar in trace element composition to continental tholeiitic sequences. The Burnt Lake felsic pyroclastic suite comprises rhyolitic pyroclastics having major and trace element compositions that suggest that they were derived from crustal melts. Rare earth element models suggest that the Burnt Lake back-arc tholeiitic rocks were formed by fractional crystallization of mafic magmas derived by approximately 5% partial melting of an amphibole-bearing depleted mantle, enriched in light rare earth elements by a subduction component. The modelling also suggests that the Burnt Lake continental tholeiitic rocks were formed by contamination – fractional crystallization of mixtures of mafic magmas, derived by ~3% partial melting of the subduction-modified source, and rhyolitic crustal melts. These models are consistent with the suggestion that the Belmont Domain of the Central Metasedimentary Belt formed as a back-arc basin by attenuation of preexisting continental crust above a westerly dipping subduction zone.

Zircon U–Pb chronology, geochemistry, and petrogenesis of the high Nb–Ta alkaline rhyolites at the Tuohe Tree Farm, northern Volcanic Belt, Great Xing’an Range, China

2019 ◽  
Vol 56 (10) ◽  
pp. 1003-1016
Author(s):  
Guosheng Sun ◽  
Tianxue Zhao ◽  
Ruixiang Jin ◽  
Qinghai Wang
Keyword(s):  
Partial Melting ◽  
Hot Spot ◽  
Basaltic Magma ◽  
Source Region ◽  
Volcanic Belt ◽  
Source Rocks ◽  
Crustal Rocks ◽  
Depleted Mantle ◽  
Sample Points ◽  
Great Xing’An Range

We studied newly found high Nb–Ta alkaline rhyolites in the northern volcanic belt of the Great Xing’an Range, China. The LA–ICP–MS U–Pb weighted mean age is 114.07 ± 0.55 Ma, indicating that the rocks formed during the late Early Cretaceous and were the product of the late eruption of a Mesozoic volcano. The major element contents are characterized by high Si, rich K, low Fe, and poor Ca and Mg. In the total alkaline–silicon diagram, the sample points are in the alkaline rhyolite region. Meanwhile, rare earth elements show obvious Ce/Ce* positive anomalies and Eu/Eu* negative anomalies. In addition, trace elements are characterized by high Nb, Ta, and Yb, and low Sr. The two-stage Nd isotopic model age T2DM of the depleted mantle is between 799–813 Ma, indicating that the diagenetic material originated from the depleted mantle or partial melting of newly formed young crustal materials. The source rocks melted at a relative shallow depth (<30 km), under lower pressure (<0.5 Gpa) and high oxygen fugacity; moreover, the residues in the source region were Ca-rich mafic plagioclase + amphibole + orthopyroxene. In the Nb–Y–3Ga and Nb–Y–Ce diagrams, the sample points are in the A1 type region. It can be concluded that the mantle-derived basaltic magma underplated and supplied the heat sources for partial melting of the metamorphic crustal rocks in an intraplate extensional tectonic environment related to a rift, mantle plume, and hot spot.

scholarly journals Ore and Geochemical Specialization and Substance Sources of the Ural and Timan Carbonatite Complexes (Russia): Insights from Trace Element, Rb–Sr, and Sm–Nd Isotope Data

Minerals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 711
Author(s):  
Irina Nedosekova ◽  
Nikolay Vladykin ◽  
Oksana Udoratina ◽  
Boris Belyatsky
Keyword(s):  
Trace Element ◽  
Mantle Source ◽  
Crustal Evolution ◽  
Trace Element Data ◽  
The Urals ◽  
Nd Isotope ◽  
Enriched Mantle ◽  
Depleted Mantle ◽  
Mantle Sources ◽  
Geochemical Specialization

The Ilmeno–Vishnevogorsk (IVC), Buldym, and Chetlassky carbonatite complexes are localized in the folded regions of the Urals and Timan. These complexes differ in geochemical signatures and ore specialization: Nb-deposits of pyrochlore carbonatites are associated with the IVC, while Nb–REE-deposits with the Buldym complex and REE-deposits of bastnäsite carbonatites with the Chetlassky complex. A comparative study of these carbonatite complexes has been conducted in order to establish the reasons for their ore specialization and their sources. The IVC is characterized by low 87Sr/86Sri (0.70336–0.70399) and εNd (+2 to +6), suggesting a single moderately depleted mantle source for rocks and pyrochlore mineralization. The Buldym complex has a higher 87Sr/86Sri (0.70440–0.70513) with negative εNd (−0.2 to −3), which corresponds to enriched mantle source EMI-type. The REE carbonatites of the Chetlassky сomplex show low 87Sr/86Sri (0.70336–0.70369) and a high εNd (+5–+6), which is close to the DM mantle source with ~5% marine sedimentary component. Based on Sr–Nd isotope signatures, major, and trace element data, we assume that the different ore specialization of Urals and Timan carbonatites may be caused not only by crustal evolution of alkaline-carbonatite magmas, but also by the heterogeneity of their mantle sources associated with different degrees of enrichment in recycled components.

scholarly journals Geochemistry and petrology of mafic Proterozoic and Permian dykes on Bornholm, Denmark: Four Episodes of magmatism on the margin of the Baltic Shield

2010 ◽  
Vol 58 ◽  
pp. 35-65
Author(s):  
Paul Martin Holm ◽  
L.E. Pedersen, ◽  
B Højsteen
Keyword(s):  
Mantle Plume ◽  
Mantle Source ◽  
Small Degree ◽  
Spinel Peridotite ◽  
Alkali Basalts ◽  
Enriched Mantle ◽  
Depleted Mantle ◽  
Proterozoic Basement ◽  
The Baltic ◽  
Back Arc

More than 250 dykes cut the mid Proterozoic basement gneisses and granites of Bornholm. Most trend between NNW and NNE, whereas a few trend NE and NW. Field, geochemical and petrological evidence suggest that the dyke intrusions occurred as four distinct events at around 1326 Ma (Kelseaa dyke), 1220 Ma (narrow dykes), 950 Ma (Kaas and Listed dykes), and 300 Ma (NW-trending dykes), respectively. The largest dyke at Kelseaa (60 m wide) and some related dykes are primitive olivine tholeiites, one of which has N-type MORB geochemical features; all are crustally contaminated. The Kelseaa type magmas were derived at shallow depth from a fluid-enriched, relatively depleted, mantle source,but some have a component derived from mantle with residual garnet. They are suggested to have formed in a back-arc environment. The more than 200 narrow dykes are olivine tholeiites (some picritic), alkali basalts, trachybasalts, basanites and a few phonotephrites. The magmas evolved by olivine and olivine + clinopyroxene fractionation. They have trace element characteristics which can be described mainly by mixing of two components: one is a typical OIB-magma (La/Nb < 1, Zr/Nb = 4, Sr/Nd = 16) and rather shallowly derived from spinel peridotite; the other is enriched in Sr and has La/Nb = 1.0 - 1.5, Zr/Nb = 9, Sr/Nd = 30 and was derived at greater depth, probably from a pyroxenitic source. Both sources were probably recycled material in a mantle plume. A few of these dykes are much more enriched in incompatible elements and were derived from garnet peridotite by a small degree of partial melting. The Kaas and Listed dykes (20-40 m) and related dykes are evolved trachybasalts to basaltic trachyandesites. They are most likely related to the Blekinge Dalarne Dolerite Group. The few NW-trending dykes are quartz tholeiites, which were generated by large degrees of rather shallow melting of an enriched mantle source more enriched than the source of the older Bornholm dykes. The source of the NW-trending dykes was probably a very hot mantle plume.

Origin of Late Triassic mafic–ultramafic intrusions in the Hongqiling Ni–Cu sulfide deposit, Northeast China: evidence from trace element and Sr–Nd isotope geochemistry

2018 ◽  
Vol 55 (12) ◽  
pp. 1312-1323 ◽  
Author(s):  
Xinyun Zhao ◽  
Libo Hao ◽  
Qiaoqiao Wei ◽  
Qingqing Liu ◽  
Jian Zhou ◽  
...  
Keyword(s):  
Trace Element ◽  
Partial Melting ◽  
Northeast China ◽  
Eastern China ◽  
Crustal Contamination ◽  
Late Triassic ◽  
Substantial Contribution ◽  
Sulfide Deposit ◽  
Magma Evolution ◽  
Depleted Mantle

There are many Late Triassic mafic–ultramafic intrusions in the Hongqiling magmatic Ni–Cu sulfide deposit, Northeast China. Research on magma evolution leading to formation of these mafic–ultramafic intrusions is of great significance for understanding the mantle beneath Northeast China and associated Ni–Cu mineralization. A trace element study of the No. 1, 3, and 7 intrusions in the Hongqiling deposit reveals that these mafic–ultramafic intrusions are characterized by enrichment of incompatible elements, which however cannot be interpreted by subduction modification. Furthermore, model of batch partial melting of depleted mantle accompanied by upper crustal contamination can simulate the trace element patterns of these mafic–ultramafic intrusions, but partial melting of depleted mantle accompanied by lower crustal contamination model cannot work. In addition, Sr–Nd isotopic compositions of the Hongqiling No. 1, 3, and 7 intrusions also indicate that crustal contamination could have occurred mainly during the magma ascent. Consequently, a possible scenario for the magma evolution is that the primary mafic–ultramafic magma was derived from batch partial melting of a depleted mantle, and then contaminated by Cambrian–Ordovician metamorphic rocks of the Hulan Group during ascent. We conclude that the mantle source contained no significant crustal component in the Late Triassic and was also independent of substantial contribution from subducted material, and therefore the Mesozoic large-scale lithospheric delamination beneath eastern China may happen after a period of time of the Late Triassic.

Geochemistry of Siluro-Devonian Tobique volcanic belt in northern and central New Brunswick (Canada): tectonic implications

1989 ◽  
Vol 26 (6) ◽  
pp. 1282-1296 ◽  
Author(s):  
J. Dostal ◽  
R. A. Wilson ◽  
J. D. Keppie
Keyword(s):  
New Brunswick ◽  
Mantle Source ◽  
Upper Mantle ◽  
Volcanic Rocks ◽  
Volcanic Belt ◽  
Continental Rift ◽  
Basaltic Rocks ◽  
Incompatible Elements ◽  
Tectonic Implications

Siluro-Devonian volcanic rocks of the northwestern mainland Appalachians are found mainly in the Tobique belt of New Brunswick where they consist predominantly of bimodal mafic–felsic suites erupted in a continental-rift environment. The axis of the Tobique rift trends north-northeast – south-southwest, obliquely to the regional northeast–southwest trend of the Appalachians. These geometric relationships are interpreted as being the result of rifting in a sinistral shear regime produced during emplacement of the Avalon terrene. The basaltic rocks are continental tholeiites and transitional basalts derived from a heterogeneous upper-mantle source that was enriched in incompatible elements relative to the primordial mantle. The mantle source was probably affected by the subduction processes.

Discerning asthenospheric, lithospheric, and crustal influences on the geochemistry of Quaternary basalts from the Iskut–Unuk rivers area, northwestern British Columbia

1995 ◽  
Vol 32 (9) ◽  
pp. 1451-1461 ◽  
Author(s):  
Brian L. Cousens ◽  
Mary Lou Bevier
Keyword(s):  
Volcanic Rocks ◽  
Volcanic Belt ◽  
Volcanic Field ◽  
Northwest Pacific ◽  
Small Range ◽  
Geochemical Composition ◽  
Basaltic Rocks ◽  
Depleted Mantle ◽  
Mid Ocean Ridge ◽  
Ocean Ridge

Pleistocene- to Holocene-age basaltic rocks of the Iskut–Unuk rivers volcanic field, at the southern terminus of the Stikine Volcanic Belt in the northern Canadian Cordillera, provide information on the geochemical composition of the underlying mantle and processes that have modified parental magmas. Basaltic rocks from four of the six eruptive centres are moderately evolved (MgO = 5.7–6.8%) alkaline basalts with chondrite-normalized La/Sm = 1.6–1.8, 87Sr/86Sr = 0.70336–0.70361, εNd = +4.4 to +5.9, and 206Pb/204Pb = 19.07–19.22. The small range of isotopic compositions and incompatible element ratios imply a common "depleted" mantle source for the basalts, similar to the sources of enriched mid-ocean ridge basalts from northwest Pacific spreading centres or alkali olivine basalts from the western Yukon. Positive Ba and negative Nb anomalies that increase in size with increasing SiO2 and 87Sr/86Sr indicate that the basalts are contaminated by Mesozoic-age, arc-related, Stikine Terrane crust or lithospheric mantle through which the magmas passed. Lavas from a fifth volcanic centre, Cinder Mountain, have undergone greater amounts of fractional crystallization and are relatively enriched in incompatible elements, but are isotopically identical to least-contaminated Iskut–Unuk rivers basalts. Iskut–Unuk rivers lavas share many of the geochemical characteristics of volcanic rocks from other Stikine Belt and Anahim Belt centres, as well as alkali olivine basalts from the Fort Selkirk volcanic centres of the western Yukon.

Mantle source characteristics of Triassic alkaline lavas within the Antalya Nappes, SW Turkey

2020 ◽  
Author(s):  
Ercan Aldanmaz ◽  
Aykut Güçtekin ◽  
Özlem Yıldız-Yüksekol
Keyword(s):  
Trace Element ◽  
Partial Melting ◽  
Mantle Source ◽  
Carbonate Platform ◽  
Incompatible Trace Element ◽  
Late Triassic ◽  
Radiogenic Isotope ◽  
Basaltic Rocks ◽  
Sw Turkey ◽  
End Members

&lt;p&gt;The Late Triassic basaltic rocks that are dispersed as several lava sheets in a number of different tectonic slices within the Antalya nappes in SW Turkey represent the remnants of widespread oceanic magmatism with strong intra-plate geochemical signatures. The largest exposures are observed around the Antalya Bay, where pillow structured or massif lava flows are interlayered with Upper Triassic pelagic or carbonate platform sediments. Based on bulk-rock geochemical characteristics, the rocks mostly classify as alkaline basalts and display distinctive OIB-type trace element distributions characterized by significant enrichments in LILE and HFSE abundances, as well as LREE/HREE ratios, with respect to average N-MORB. Quantitative modeling of trace element data suggest that the primary melts that produced the alkaline lavas are largely the products of variable proportions of mixing between melts generated by variable, but generally low (&lt;10) degrees of partial melting of more than one compositionally distinct mantle source. The samples, as a whole, display large variations in radiogenic isotope ratios with &lt;sup&gt;87&lt;/sup&gt;Sr/&lt;sup&gt;86&lt;/sup&gt;Sr = 0.703021&amp;#8211;0.70553, &lt;sup&gt;143&lt;/sup&gt;Nd/&lt;sup&gt;144&lt;/sup&gt;Nd = 0.51247&amp;#8211;0.51279, &lt;sup&gt;206&lt;/sup&gt;Pb/&lt;sup&gt;204&lt;/sup&gt;Pb = 18.049&amp;#8211;20.030, &lt;sup&gt;207&lt;/sup&gt;Pb/&lt;sup&gt;204&lt;/sup&gt;Pb = 15.544&amp;#8211;15.723 and &lt;sup&gt;208&lt;/sup&gt;Pb/&lt;sup&gt;204&lt;/sup&gt;Pb = 38.546&amp;#8211;39.530. Such variations in isotopic ratios correlate with the change in incompatible trace element relative abundances and reflect the involvement of a number of compositionally distinct mantle end-members. These include EMI and EMII type enriched mantle components both having lower &lt;sup&gt;143&lt;/sup&gt;Nd/&lt;sup&gt;144&lt;/sup&gt;Nd than typical depleted MORB source with their contrasting low and high &lt;sup&gt;206&lt;/sup&gt;Pb/&lt;sup&gt;204&lt;/sup&gt;Pb and &lt;sup&gt;20&lt;/sup&gt;&lt;sup&gt;7&lt;/sup&gt;Pb/&lt;sup&gt;204&lt;/sup&gt;Pb ratios respectively, as well as a high time-integrated &lt;sup&gt;238&lt;/sup&gt;U/&lt;sup&gt;204&lt;/sup&gt;Pb component with high &lt;sup&gt;206&lt;/sup&gt;Pb/&lt;sup&gt;204&lt;/sup&gt;Pb at relatively low &lt;sup&gt;87&lt;/sup&gt;Sr/&lt;sup&gt;86&lt;/sup&gt;Sr and &amp;#949;Nd values. The results from trace element and radiogenic isotope data are consistent with the view that the initial melt generation was likely related to partial melting of the shallow convecting upper mantle in response to Triassic rifting events, while continued mantle upwelling resulted in progressively increased melting of mantle lithosphere that contained compositionally contrasting lithological domains with strong isotopic heterogeneities.&lt;/p&gt;

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