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10. Boron isotope composition of coexisting tourmaline and hambergite in alkaline and granitic pegmatites

Author

Sunde, Øyvind, Friis, Henrik, Andersen, Tom, Trumbull, Robert B, Wiedenbeck, Michael, Lyckberg, Peter, Agostini, Samuele, Casey, William H, and Yu, Ping

Subjects
Boron isotopes, Pegmatites, Alkaline, Tourmaline, Hambergite, Geochemistry, Geology, Geophysics, Geochemistry & Geophysics
Abstract

The boron isotopic composition of tourmaline and hambergite (Be2BO3[OH,F]) from peraluminous (n = 12), peralkaline (n = 1), and peralkaline nepheline syenite (n = 16) pegmatites has been measured by secondary ion mass spectrometry, for which a new hambergite reference material was developed. The focus of this study is on nepheline syenite pegmatites from the Larvik Plutonic Complex (Norway) and one peralkaline pegmatite related to the nearby Eikeren-Skrim Complex (Norway), where we investigate the source of boron as being from magmatic vs. external fluids. Tourmaline-hambergite mineral pairs were also analysed from peraluminous pegmatite localities (Russia, Tajikistan, and Pakistan) to test for systematic B-isotope fractionation between these two minerals. Tourmaline and hambergite from peraluminous granitic pegmatites have light boron ratios (δ11B = −12.9to −1.0‰) associated with S-type granites, whereas peralkaline granitic and nepheline syenite pegmatites have boron ratios (δ11B = −1.7 to 11.8‰), which we interpret is a result of heavy‑boron enrichment from external fluids. Our data show that hambergite tracks isotope variations of its geochemical setting and could therefore be used as a proxy mineral in place of tourmaline when geochemical stability favours hambergite. The results suggest a slight but consistent partitioning of B-isotopes between tourmaline and hambergite, with Δ11B = δ11Btourmaline−δ11Bhambergite in the range of approximately −3‰ to −5‰. Boron is in trigonal coordination with oxygen in both of these mineral phases as verified by NMR. Single crystal XRD analyses of tourmaline and hambergite reveal consistent longer distances of tourmaline relative to hambergite. We attribute the boron isotopic fractionation to the longer bond-lengths in tourmaline compared with hambergite.

Published
2020

32. HOW DO ORE DEPOSITS FORM?

Author

Trumbull, Robert B. and Codeço, Marta S.

Subjects
ORE deposits, MINES & mineral resources, PLATINUM mining, HYDROTHERMAL deposits
Abstract

This article discusses how ore deposits form and where they can be found. Ore deposits are rocks rich in metal that are mined to obtain the metals needed for everyday life. The article explains that there are two main types of ore deposits: hydrothermal and magmatic deposits. Hydrothermal deposits form when metals are dissolved in hot water and transported through cracks in rocks. Magmatic deposits form when minerals in deep rocks are melted and transported upwards in liquid magma. The article emphasizes the importance of scientific drilling to study ore deposits in detail and find new ones. The Bushveld Drilling Project in South Africa is highlighted as an example of a project studying the world's largest ore deposit of platinum. The article concludes by stating that ore deposits will continue to be the main source of metals for many years to come, and scientific research is crucial for understanding how they form and finding new deposits. [Extracted from the article]

Published
2023
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33. Partial Melting in the Central Andean Crust: a Review of Geophysical, Petrophysical, and Petrologic Evidence

Author

Schilling, Frank R., Trumbull, Robert B., Brasse, Heinrich, Haberland, Christian, Asch, Günter, Bruhn, David, Mai, Katrin, Haak, Volker, Giese, Peter, Muñoz, Miguel, Ramelow, Juliane, Rietbrock, Andreas, Ricaldi, Edgar, Vietor, Tim, Brun, J. P., editor, Oncken, O., editor, Weissert, H., editor, Dullo, C., editor, Oncken, Onno, editor, Chong, Guillermo, editor, Franz, Gerhard, editor, Giese, Peter, editor, Götze, Hans-Jürgen, editor, Ramos, Victor A., editor, Strecker, Manfred R., editor, and Wigger, Peter, editor

Published
2006
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34. Numerical Study of Weakening Processes in the Central Andean Back-Arc

Author

Babeyko, Andrey Y., Sobolev, Stephan V., Vietor, Tim, Oncken, Onno, Trumbull, Robert B., Brun, J. P., editor, Oncken, O., editor, Weissert, H., editor, Dullo, C., editor, Oncken, Onno, editor, Chong, Guillermo, editor, Franz, Gerhard, editor, Giese, Peter, editor, Götze, Hans-Jürgen, editor, Ramos, Victor A., editor, Strecker, Manfred R., editor, and Wigger, Peter, editor

Published
2006
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35. Upper-Crustal Structure of the Central Andes Inferred from Dip Curvature Analysis of Isostatic Residual Gravity

Author

Riller, Ulrich, Götze, Hans-Jürgen, Schmidt, Sabine, Trumbull, Robert B., Hongn, Fernando, Petrinovic, Ivan Alejandro, Brun, J. P., editor, Oncken, O., editor, Weissert, H., editor, Dullo, C., editor, Oncken, Onno, editor, Chong, Guillermo, editor, Franz, Gerhard, editor, Giese, Peter, editor, Götze, Hans-Jürgen, editor, Ramos, Victor A., editor, Strecker, Manfred R., editor, and Wigger, Peter, editor

Published
2006
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36. The Time-Space Distribution of Cenozoic Volcanism in the South-Central Andes: a New Data Compilation and Some Tectonic Implications

Author

Trumbull, Robert B., Riller, Ulrich, Oncken, Onno, Scheuber, Ekkehard, Munier, Kerstin, Hongn, Fernando, Brun, J. P., editor, Oncken, O., editor, Weissert, H., editor, Dullo, C., editor, Oncken, Onno, editor, Chong, Guillermo, editor, Franz, Gerhard, editor, Giese, Peter, editor, Götze, Hans-Jürgen, editor, Ramos, Victor A., editor, Strecker, Manfred R., editor, and Wigger, Peter, editor

Published
2006
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37. Crustal Evolution at the Central Andean Continental Margin: a Geochemical Record of Crustal Growth, Recycling and Destruction

Author

Franz, Gerhard, Lucassen, Friedrich, Kramer, Wolfgang, Trumbull, Robert B., Romer, Rolf L., Wilke, Hans-Gerhard, Viramonte, José G., Becchio, Raúl, Siebel, Wolfgang, Brun, J. P., editor, Oncken, O., editor, Weissert, H., editor, Dullo, C., editor, Oncken, Onno, editor, Chong, Guillermo, editor, Franz, Gerhard, editor, Giese, Peter, editor, Götze, Hans-Jürgen, editor, Ramos, Victor A., editor, Strecker, Manfred R., editor, and Wigger, Peter, editor

Published
2006
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40. Introduction

Author

Trumbull, Robert B., Morteani, Giulio, Li, Zhiliang, Bai, Hongsheng, Trumbull, Robert B., Morteani, Giulio, Li, Zhiliang, and Bai, Hongsheng

Published
1992
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41. Aspects of Metallogenesis

Author

Trumbull, Robert B., Morteani, Giulio, Li, Zhiliang, Bai, Hongsheng, Trumbull, Robert B., Morteani, Giulio, Li, Zhiliang, and Bai, Hongsheng

Published
1992
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