Mapping magma sources in the east Sunda-Banda arcs, Indonesia: Constraints from helium isotopes

Hilton, David R.; Hoogewerff, Jurian; Bergen, Manfred J. van; Hammerschmidt, Konrad

doi:10.1016/0016-7037(92)90105-r

Cited by 115 publications

(62 citation statements)

References 35 publications

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“…The lowest 3 He/ 4 He values (0.7^3.4 R A ) are found in water spring samples, and point to a signi¢cant radiogenic He contribution. Based on prior arguments against He being subducted into the mantle [24], the presence of radiogenic He likely re£ects contamination processes in the uppermost crust (see also Section 5.1). The bubbling hot spring and geothermal well samples show varying degrees of crustal interaction with 3 He/ 4 He ratios ranging from 2 R A to MORB-like values.…”

Section: Resultsmentioning

confidence: 99%

Contrasting He–C relationships in Nicaragua and Costa Rica: insights into C cycling through subduction zones

Shaw

Hilton

Fischer

et al. 2003

Earth and Planetary Science Letters

166

160

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We report 3 He/ 4 He ratios, relative He, Ne, and CO 2 abundances as well as N 13 C values for volatiles from the volcanic output along the Costa Rica and Nicaragua segments of the Central American arc utilising fumaroles, geothermal wells, water springs and bubbling hot springs. CO 2 / 3 He ratios are relatively constant throughout Costa Rica (av. 2.1U10 10 ) and Nicaragua (av. 2.5U10 10 ) and similar to arcs worldwide (V1.5U10 10 ). N 13 C values range from 36.8x (MORB-like) to 30.1x (similar to marine carbonate (0x)). 3 He/ 4 He ratios are essentially MORBlike (8 þ 1 R A ) with some samples showing evidence of crustal He additions^water spring samples are particularly susceptible to modification. The He^CO 2 relationships are consistent with an enhanced input of slab-derived C to magma sources in Nicaragua ((L+S)/M = 16; where L, M and S represent the fraction of CO 2 derived from limestone and/or marine carbonate (L), the mantle (M) and sedimentary organic C (S) sources) relative to Costa Rica ((L+S)/ M = 10). This is consistent with prior studies showing a higher sedimentary flux to the arc volcanics in Nicaragua (as traced by Ba/La, 10 Be and La/Yb). Possible explanations include: (1) offscraping of the uppermost sediments in the Costa Rica forearc, and (2) a cooler thermal regime in the Nicaragua subduction zone, preserving a higher proportion of melt-inducing fluids to subarc depths, leading to a higher degree of sediment transfer to the subarc mantle. The absolute flux of CO 2 from the Central American arc as determined by correlation spectrometry methods (5.8U10 10 mol/yr) and CO 2 / 3 He ratios (7.1U10 10 mol/yr) represents approximately 14^18% of the amount of CO 2 input at the trench from the various slab contributors (carbonate sediments, organic C, and altered oceanic crust). Although the absolute flux is comparable to other arcs, the efficiency of CO 2 recycling through the Central American arc is surprisingly low (14^18% vs. a global average of V50%). This may be attributed to either significant C loss in the forearc region, or incomplete decarbonation of carbonate sediments at subarc depths. The implication of the latter case is that a large fraction of C (up to 86%) may be transferred to the deep mantle (depths beyond the source of arc magmas). ß

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Section: Resultsmentioning

confidence: 99%

Contrasting He–C relationships in Nicaragua and Costa Rica: insights into C cycling through subduction zones

Shaw

Hilton

Fischer

et al. 2003

Earth and Planetary Science Letters

166

160

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“…Samples were crushed by a magnetic piston (500 strokes) operated by computer-con trolled external solenoids. (Hilton et al, 1992). Typical blanks were 2.5-5 x 10-15 mol 4He and 2-4 x 10-14 mol 40Ar with atmospheric ratios for the latter .…”

Section: Geological Setting and Samplesmentioning

confidence: 97%

He, Ar, Sr, Nd and Pb isotopes in volcanic rocks from Afar: Evidence for a primitive mantle component and constraints on magmatic sources.

et al. 1993

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He, Ar, Sr, Nd and Pb isotopic ratios have been determined for a set of submarine basaltic glasses from the Gulf of Tadjoura and subaerial lavas from Afar, Republic of Djibuti. Rare gases were recovered by vacuum crushing and analysed with a new analytical system. Helium isotopic ratios up to 15 Ra show the occurrence of a "high 3He" hot spot beneath Afar and indicate the occurrence of a plume originating from a gas-rich, presumably deep, region of the mantle. He-Ar isotope systematics in dicate a mixing between three geochemical end-members: the plume component, enriched in 3He, a radiogenic, possibly crustal, component, and the atmosphere. Low 40Ar/36Ar ratios are interpreted as the result of selective atmospheric contamination of Afar magmas, but the process of contamination is unclear. In a He-Sr-Nd-Pb space, Afar data are plotted in a field similar to basic lavas emitted in Iceland (Djibuti territory) and in the Reykjanes Ridge (Gulf of Tadjoura) and differ by their He isotopic ratios from lavas emitted in EM (e.g., Gough and Tristan da Cunha) and HIMU (e.g., Saint Helena and Tubuaii) hot spots analysed so far.

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“…Elburg et al 2002) and possibly of blocks of extended continental crust close to the continent-ocean transition (e.g. Hilton et al 1992).…”

Section: C Recycling Of Laurentian Continental Materials In Arc Magmentioning

confidence: 99%

Laurentian crustal recycling in the Ordovician Grampian Orogeny: Nd isotopic evidence from western Ireland

et al. 2004

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-Because magmatism associated with subduction is thought to be the principal source for continental crust generation, assessing the relative contribution of pre-existing (subducted and assimilated) continental material to arc magmatism in accreted arcs is important to understanding the origin of continental crust. We present a detailed Nd isotopic stratigraphy for volcanic and volcaniclastic formations from the South Mayo Trough, an accreted oceanic arc exposed in the western Irish Caledonides. These units span an arc-continent collision event, the Grampian (Taconic) Orogeny, in which an intra-oceanic island arc was accreted onto the passive continental margin of Laurentia starting at ∼ 475 Ma (Arenig). The stratigraphy corresponding to pre-, syn-and postcollisional volcanism reveals a progression of ε Nd(t) from strongly positive values, consistent with melt derivation almost exclusively from oceanic mantle beneath the arc, to strongly negative values, indicating incorporation of continental material into the melt. Using ε Nd(t) values of meta-sediments that represent the Laurentian passive margin and accretionary prism, we are able to quantify the relative proportions of continent-derived melt at various stages of arc formation and accretion. Mass balance calculations show that mantle-derived magmatism contributes substantially to melt production during all stages of arc-continent collision, never accounting for less than 21 % of the total. This implies that a significant addition of new, rather than recycled, continental crust can accompany arc-continent collision and continental arc magmatism.

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Mapping magma sources in the east Sunda-Banda arcs, Indonesia: Constraints from helium isotopes

Cited by 115 publications

References 35 publications

Contrasting He–C relationships in Nicaragua and Costa Rica: insights into C cycling through subduction zones

Contrasting He–C relationships in Nicaragua and Costa Rica: insights into C cycling through subduction zones

He, Ar, Sr, Nd and Pb isotopes in volcanic rocks from Afar: Evidence for a primitive mantle component and constraints on magmatic sources.

Laurentian crustal recycling in the Ordovician Grampian Orogeny: Nd isotopic evidence from western Ireland

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