Geology, geochemistry and evolution of the Esfordi Phosphate - Iron Deposit, Bafq Area, Central Iran
Esfordi is a Kiruna-type Fe–P oxide deposit in the Bafq district of Iran. It formed within a predominantly rhyolitic volcanic sequence that formed in a continental margin tectonic regime and is of Cambrian age. The gently dipping, stratabound ore body is lenticular and displays a well-developed mine...
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ftdatacite:10.26190/unsworks/17736 2023-05-15T17:04:22+02:00 Geology, geochemistry and evolution of the Esfordi Phosphate - Iron Deposit, Bafq Area, Central Iran Jami, Morteza 2005 https://dx.doi.org/10.26190/unsworks/17736 http://hdl.handle.net/1959.4/32745 unknown UNSW Sydney https://creativecommons.org/licenses/by-nc-nd/3.0/au/ cc by-nc-nd 3.0 CC-BY-NC-ND Geology - Iran Geochemistry - Iran Dissertation thesis Thesis doctoral thesis 2005 ftdatacite https://doi.org/10.26190/unsworks/17736 2022-04-01T18:57:04Z Esfordi is a Kiruna-type Fe–P oxide deposit in the Bafq district of Iran. It formed within a predominantly rhyolitic volcanic sequence that formed in a continental margin tectonic regime and is of Cambrian age. The gently dipping, stratabound ore body is lenticular and displays a well-developed mineralogical zonal pattern. The Fe-oxide rich core contains a central zone of massive magnetite and a more hematitic brecciated rim. The overlying P-rich ore body contains massive and brecciated, apatite-rich variants with accessory hematite and actinolite. A zone of apatite-bearing veins and disseminations envelopes the Fe-oxide and P-rich zones and extends into overlying volcaniclastics that contain detrital magnetite ± apatite clasts. The main ore zones are surrounded by Ca-rich alteration, dominated by actinolite, extending ~100 m into the more permeable overlying volcaniclastics. Beyond this envelope is widespread development of secondary K-feldspar. Mesoscopic and microscopic observations reveal a paragenetic sequence containing four generations of apatite. The early stage is a LREE-rich apatite 1 that occurs within the massive and brecciated magnetite core. The second generation is large and brecciated apatite 2, associated with hematite and actinolite. Both apatite 1 and 2 exhibit widespread dissolution and reprecipitation to form a LREE-poor granular apatite that is generally associated with quartz-carbonate±REE minerals. The final stage involved an overprint of LREE-poor apatite 3-carbonate-quartz-actinolite-chlorite-epidote±bastnaesite±synchesite extending into the host rocks. Fluid inclusions in apatite 1 have homogenisation temperatures of 375-425oC and indicate salinities of 14–18 wt. % NaCl. The magnetite displays low δ¹⁸O of -0.1–1.7 ‰, suggesting precipitation from fluids with δ¹⁸O of 7.8–9.6 ‰ at ~400oC, consistent with a magmatic source. Fluid inclusions in apatite 2 homogenise between 195–295oC with indicated salinities of 13–19 wt. % NaCl. The associated hematite displays δ¹⁸O of -0.2–2.3 ‰ which would be in equilibrium with fluids having a δ¹⁸O of 10.7–13.0 ‰ at ~250oC. Such enriched isotopic fluids suggest interaction of magmatic fluids with cooler saline fluids that were probably derived from the underlying carbonate-rich sequences. Fluid inclusions in apatite 3 and quartz homogenise at 145–155oC and, together with a quartz δ¹⁸O of 16.0–17.1 ‰, suggests precipitation from a fluid with δ¹⁸O of -0.7–2.1 ‰ that is likely to have resulted from the introduction of a cooler, less saline and isotopically depleted fluid (such as sea water). The results of this study clearly indicate a significant role for fluids in the evolution of the Esfordi deposit but do not preclude a role for immiscible Fe-oxide��������P-rich melts in the initial stages of the mineralising process. Doctoral or Postdoctoral Thesis Kiruna DataCite Metadata Store (German National Library of Science and Technology) Kiruna |
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topic |
Geology - Iran Geochemistry - Iran |
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Geology - Iran Geochemistry - Iran Jami, Morteza Geology, geochemistry and evolution of the Esfordi Phosphate - Iron Deposit, Bafq Area, Central Iran |
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Geology - Iran Geochemistry - Iran |
description |
Esfordi is a Kiruna-type Fe–P oxide deposit in the Bafq district of Iran. It formed within a predominantly rhyolitic volcanic sequence that formed in a continental margin tectonic regime and is of Cambrian age. The gently dipping, stratabound ore body is lenticular and displays a well-developed mineralogical zonal pattern. The Fe-oxide rich core contains a central zone of massive magnetite and a more hematitic brecciated rim. The overlying P-rich ore body contains massive and brecciated, apatite-rich variants with accessory hematite and actinolite. A zone of apatite-bearing veins and disseminations envelopes the Fe-oxide and P-rich zones and extends into overlying volcaniclastics that contain detrital magnetite ± apatite clasts. The main ore zones are surrounded by Ca-rich alteration, dominated by actinolite, extending ~100 m into the more permeable overlying volcaniclastics. Beyond this envelope is widespread development of secondary K-feldspar. Mesoscopic and microscopic observations reveal a paragenetic sequence containing four generations of apatite. The early stage is a LREE-rich apatite 1 that occurs within the massive and brecciated magnetite core. The second generation is large and brecciated apatite 2, associated with hematite and actinolite. Both apatite 1 and 2 exhibit widespread dissolution and reprecipitation to form a LREE-poor granular apatite that is generally associated with quartz-carbonate±REE minerals. The final stage involved an overprint of LREE-poor apatite 3-carbonate-quartz-actinolite-chlorite-epidote±bastnaesite±synchesite extending into the host rocks. Fluid inclusions in apatite 1 have homogenisation temperatures of 375-425oC and indicate salinities of 14–18 wt. % NaCl. The magnetite displays low δ¹⁸O of -0.1–1.7 ‰, suggesting precipitation from fluids with δ¹⁸O of 7.8–9.6 ‰ at ~400oC, consistent with a magmatic source. Fluid inclusions in apatite 2 homogenise between 195–295oC with indicated salinities of 13–19 wt. % NaCl. The associated hematite displays δ¹⁸O of -0.2–2.3 ‰ which would be in equilibrium with fluids having a δ¹⁸O of 10.7–13.0 ‰ at ~250oC. Such enriched isotopic fluids suggest interaction of magmatic fluids with cooler saline fluids that were probably derived from the underlying carbonate-rich sequences. Fluid inclusions in apatite 3 and quartz homogenise at 145–155oC and, together with a quartz δ¹⁸O of 16.0–17.1 ‰, suggests precipitation from a fluid with δ¹⁸O of -0.7–2.1 ‰ that is likely to have resulted from the introduction of a cooler, less saline and isotopically depleted fluid (such as sea water). The results of this study clearly indicate a significant role for fluids in the evolution of the Esfordi deposit but do not preclude a role for immiscible Fe-oxide��������P-rich melts in the initial stages of the mineralising process. |
format |
Doctoral or Postdoctoral Thesis |
author |
Jami, Morteza |
author_facet |
Jami, Morteza |
author_sort |
Jami, Morteza |
title |
Geology, geochemistry and evolution of the Esfordi Phosphate - Iron Deposit, Bafq Area, Central Iran |
title_short |
Geology, geochemistry and evolution of the Esfordi Phosphate - Iron Deposit, Bafq Area, Central Iran |
title_full |
Geology, geochemistry and evolution of the Esfordi Phosphate - Iron Deposit, Bafq Area, Central Iran |
title_fullStr |
Geology, geochemistry and evolution of the Esfordi Phosphate - Iron Deposit, Bafq Area, Central Iran |
title_full_unstemmed |
Geology, geochemistry and evolution of the Esfordi Phosphate - Iron Deposit, Bafq Area, Central Iran |
title_sort |
geology, geochemistry and evolution of the esfordi phosphate - iron deposit, bafq area, central iran |
publisher |
UNSW Sydney |
publishDate |
2005 |
url |
https://dx.doi.org/10.26190/unsworks/17736 http://hdl.handle.net/1959.4/32745 |
geographic |
Kiruna |
geographic_facet |
Kiruna |
genre |
Kiruna |
genre_facet |
Kiruna |
op_rights |
https://creativecommons.org/licenses/by-nc-nd/3.0/au/ cc by-nc-nd 3.0 |
op_rightsnorm |
CC-BY-NC-ND |
op_doi |
https://doi.org/10.26190/unsworks/17736 |
_version_ |
1766058456716935168 |