Chapter 12. GEOCHEMISTRY OF BORON AND ITS IMPLICATIONS FOR CRUSTAL AND MANTLE PROCESSES

Leeman, William P.; Sisson, Virginia B.

doi:10.1515/9781501509223-014

Cited by 115 publications

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“…The basaltic MI contain high B contents (12-18 ppm for La Sommata and 27-36 ppm for the 1888-1890) which is a typical feature of magmas in a subduction environment (Leeman and Sisson 1996). Also, the enrichment in LILE (Ba, K) and depletion in HFSE (Nb, Zr, Ti) occurring in both the older and younger basaltic MI (Fig.…”

Section: Trace Elementsmentioning

confidence: 93%

A study of melt inclusions at Vulcano (Aeolian Islands, Italy): insights on the primitive magmas and on the volcanic feeding system

Gioncada¹,

Clocchiatti²,

Sbrana³

et al. 1998

Bulletin of Volcanology

118

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This work presents the results of a microthermometric and EPMA-SIMS study of melt inclusions in phenocrysts of rocks of the shoshonitic eruptive complex of Vulcano (Aeolian Islands, Italy). Different primitive magmas related to two different evolutionary series, an older one (50-25 ka) and a younger one (15 ka to 1890 A.D.), were identified as melt inclusions in olivine Fo 88-91 crystals. Both are characterized by high Ca/Al ratio and present very similar Rb/Sr, B/Be and patterns of trace elements, with Nb and Ti anomalies typical of a subduction zone. The two basalts present the same temperature of crystallization (1180B20 7C) and similar volatile abundances. The H 2 O, S and Cl contents are relatively high, whereas magmatic CO 2 concentrations are very low, probably due to CO 2 loss before low-pressure crystallization and entrapment of melt inclusions. The mineral chemistry of the basaltic assemblages and the high Ca/Al ratio of melt inclusions indicate an origin from a depleted, metasomatized clinopyroxene-rich peridotitic mantle. The younger primitive melt is characterized with respect to the older one by higher K 2 O and incompatible element abundances, by lower Zr/Nb and La/Nb, and by higher Ba/Rb and LREE enrichment. A different degree of partial melting of the same source can explain the chemical differences between the two magmas. However, some anomalies in Sr, Rb and K contents suggest either a slightly different source for the two magmas or differing extents of crustal contamination. Low-pressure degassing and cooling of the basaltic magmas produce shoshonitic liquids. The melt inclusions indicate evolutionary paths via fractional crystallization, leading to trachytic compositions during the older activity and to rhyolitic compositions during the recent one. The bulk-rock compositions record a more complex history than do the melt inclusions, due to the syneruptive mixing processes commonly affecting the magmas erupted at Vulcano. The composition and temperature data on melt inclusions suggest that in the older period of activity several shallow magmatic reservoirs existed; in the younger one a relatively homogeneous feeding system is active. The shallow magmatic reservoir feeding the recent eruptive activity probably has a vertical configuration, with basaltic magma in the deeper zones and differentiated magmas in shallower, low-volume, dike-like reservoirs.

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Section: Trace Elementsmentioning

confidence: 93%

A study of melt inclusions at Vulcano (Aeolian Islands, Italy): insights on the primitive magmas and on the volcanic feeding system

Gioncada¹,

Clocchiatti²,

Sbrana³

et al. 1998

Bulletin of Volcanology

118

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“…In the present-day ocean floor east of the Pacific trench, the proportion of continental sediments and carbonates is low, with the sedimentary cover dominated by clay-rich pelagic sediments (Plank and Langmuir 1998). The δ 11 B values of the altered oceanic crust are between −5‰ and +21‰ Leeman and Sisson 2002;Rosner et al 2003). Ishikawa and Nakamura (1994) stated that δ 11 B values are also influenced by the thickness of the mantle wedge but its low B content, similar to that of unaltered MORB-like crust (ca.…”

Section: Discussion: the Source Of B In The Iocg Depositsmentioning

confidence: 99%

The boron isotope geochemistry of tourmaline-rich alteration in the IOCG systems of northern Chile: implications for a magmatic-hydrothermal origin

2011

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Hydrothermal tourmaline is common in the iron oxide-copper-gold (IOCG) deposits of the Coastal Cordillera of Chile where it occurs as large crystals in the groundmass of magmatic-hydrothermal breccias, such as in the Silvita or Tropezón ore bodies, or as small grains in replacive bodies or breccia cement in the ore-bearing andesite, as seen at the Candelaria or Carola deposits. Tourmaline shows strong chemical zoning and has a composition of schorl-dravite with significant povondraite and uvite components. The observed boron isotope composition is fairly variable, between −10.4‰ and +6.0‰ with no major differences among the different deposits, suggesting a common genetic mechanism. The δ 11 B values are significantly lower than those of seawater or marine evaporites and very similar to those of younger porphyry copper deposits and volcanic rocks in the region, indicating that the boron has a common, likely magmatic, origin. The predominant boron source was ultimately dewatering of the subducting slab with a significant contribution derived from the overlying continental basement. The range of δ 11 B values is between those of the porphyry copper deposits and the porphyry tin deposits of the Andes, suggesting that the IOCG mineralization might be genetically related to fluids having more crustal contamination than the porphyry copper deposits; such an interpretation is at odds with current models that propose that the Andean IOCG deposits are related to juvenile melts or to the circulation of basinal brines. Furthermore, the obtained δ 11 B data are markedly different from those of the tourmaline in the Carajás IOCG district (Brazil), suggesting that IOCGs do not form by a unique mechanism involving only one type of fluids.

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“…The upper continental crust is highly enriched in B (17 mg/kg) relative to the primitive mantle (0.6 mg/kg) and bulk silicate Earth (0.3 mg/kg; Annovitz and Grew 1996; Leeman and Sisson 1996;McDonough and Sun 1995). Processes that dominate the B geochemical cycle in the crust include: (1) concentration in residual melts and incorporation in stable borosilicates, such as tourmaline; (2) transfer from igneous to surficial environments through volcanic exhalations; and (3) chemical and mechanical concentration in surficial environments (Leeman and Sisson 1996;Watanabe 1975). In addition, B abundance in rocks can change greatly as a consequence of rock-fluid interaction.…”

Section: Background On Boron Geochemistrymentioning

confidence: 99%

“…At neutral or slightly acidic conditions in natural waters and soils, B occurs as undissociated boric acid B(OH) 3 , a weak Lewis acid with relatively high solubility in water. At higher pH, boric acid accepts OH -to form borate ions B(OH) 4 -, whereas at high B concentrations, regardless of pH, polyborate species, such as B 3 O 3 (OH) 4 -and B 4 O 5 (OH) 4 -, become important, in addition to boric acid and borate (Leeman and Sisson 1996;Shibli and Srebnik 2005). B is an essential micronutrient for plants, but the range between deficient and toxic concentrations is unusually small (Shibli and Srebnik 2005).…”

Section: Boron In the Environmentmentioning

confidence: 99%

“…Preventive measures, tailings remediation, and water deboronation technologies (Dydo and Turek 2013;Wolska and Bryjak 2013) rely on an improved knowledge of sources of natural and anthropogenic soluble B associated with mining industries. Typical anthropogenic sources of B to the environment include industrial cleaning products, irrigation water, coal surface mining, and fly ash (Leeman and Sisson 1996;Shibli and Srebnik 2005). Elevated B contents in groundwater have been tied, at least in part, with slag deposited in industrial landfills (Senior and Sloto 2006;Yoshinaga et al 2011).…”

Section: Boron In the Environmentmentioning

confidence: 99%

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Environmentally Hazardous Boron in Gold Mine Tailings, Timmins, Ontario, Canada

Paliewicz

Sirbescu

Sulatycky³

et al. 2014

Mine Water Environ

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Traditionally, cyanide, mercury, and acid mine drainage are considered critical environmental hazards associated with gold mining. To our knowledge, this is the first study of hazardous concentrations of soluble boron (B) in a gold mine impoundment tailings dam. We suggest that the B anomaly is a consequence of disposal of gold pyrometallurgical waste (slag). Borax is a common flux used during fire assaying and refining of precious metals. Vast amounts of B-rich slag may have been discarded by mining operations and precious metal refineries worldwide, but the extent and effects of B contamination have not yet been addressed. Anomalous concentrations of soluble B found in the McIntyre mine tailings, Timmins, Ontario highly exceed recommended thresholds for groundwater, freshwater, and soil leachates, and cannot be explained by natural sources alone. Boron is distributed heterogeneously within the tailings dam and correlates positively with the percentage of B38 lm grain-size fraction, indicating that adsorption onto silt-clay particles results in B build-up.Ephemeral, efflorescent Mg-borate found along the dam embankment suggests an outflow of B along paths of high permeability. Leachability tests indicate that slags from gold-ore refineries and fire assaying labs release B12 wt% soluble B in only 24 h. This high leachability suggests that slag discarded on the tailings dam is the dominant source of observed B anomalies. Altered metabasalts with \3,000 mg/kg B may be a minor B source. Gangue minerals such as tourmaline, anhydrite, calcite, and siderite cannot account for the amount of soluble B found in the tailings.

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Chapter 12. GEOCHEMISTRY OF BORON AND ITS IMPLICATIONS FOR CRUSTAL AND MANTLE PROCESSES

Cited by 115 publications

References 0 publications

A study of melt inclusions at Vulcano (Aeolian Islands, Italy): insights on the primitive magmas and on the volcanic feeding system

A study of melt inclusions at Vulcano (Aeolian Islands, Italy): insights on the primitive magmas and on the volcanic feeding system

The boron isotope geochemistry of tourmaline-rich alteration in the IOCG systems of northern Chile: implications for a magmatic-hydrothermal origin

Environmentally Hazardous Boron in Gold Mine Tailings, Timmins, Ontario, Canada

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