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Composition and origin of the Çalda? oxide nickel laterite, W. Turkey

Composition and origin of the Çalda? oxide nickel laterite, W. Turkey
Composition and origin of the Çalda? oxide nickel laterite, W. Turkey
The Çalda? nickel laterite deposit located in the Aegean region of W. Turkey contains a reserve of 33 million tons of Ni ore with an average grade of 1.14% Ni. The deposit is developed on an ophiolitic serpentinite body which was obducted onto Triassic dolomites in the Late Cretaceous. The deposit weathering profile is both laterally and vertically variable. A limonite zone, which is the main ore horizon, is located at the base of the profile. A hematite horizon is located above the limonite, which in the south of the deposit is capped by Eocene freshwater limestones and in the north by a siliceous horizon. The deposit is unusual in lacking a significant saprolite zone with little development of Ni-silicates. The boundary between the limonite zone and serpentinite below is sharp with a marked decrease in concentrations of MgO from 13 to 1 wt.% over a distance of 2 mm representing the ‘Mg discontinuity’. Ni concentrations within goethite, the main ore mineral, reach a maximum of ~3 wt.% near the base of the limonite zone. Silica concentrations are high throughout most of the laterite with up to 80 wt.% silica in the upper portion of some profiles. The combination of a serpentinite protolith and a high water table at Çalda?, in association with an aggressive weathering environment in a tropical climate, resulted in the formation of an oxide-dominated deposit. The precipitation of silica may coincide with a change in climate with silica precipitation linked to an increase in seasonality. Additional variations within profile morphology are attributed to transportation during and after laterite development as a result of faulting, pocket type laterite formation and slumping, each of which produces a contrasting set of textural and geochemical features.
Çalda?, Nickel laterite, Limonite
0026-4598
581-595
Thorne, Robert
b7373d6b-155f-4b11-a3b7-d391debea783
Herrington, Richard
6466a9c1-3e23-40a4-a1e5-a5ce15f5a43d
Roberts, Stephen
f095c7ab-a37b-4064-8a41-ae4820832856
Thorne, Robert
b7373d6b-155f-4b11-a3b7-d391debea783
Herrington, Richard
6466a9c1-3e23-40a4-a1e5-a5ce15f5a43d
Roberts, Stephen
f095c7ab-a37b-4064-8a41-ae4820832856

Thorne, Robert, Herrington, Richard and Roberts, Stephen (2009) Composition and origin of the Çalda? oxide nickel laterite, W. Turkey. Mineralium Deposita, 44 (5), 581-595. (doi:10.1007/s00126-009-0234-6).

Record type: Article

Abstract

The Çalda? nickel laterite deposit located in the Aegean region of W. Turkey contains a reserve of 33 million tons of Ni ore with an average grade of 1.14% Ni. The deposit is developed on an ophiolitic serpentinite body which was obducted onto Triassic dolomites in the Late Cretaceous. The deposit weathering profile is both laterally and vertically variable. A limonite zone, which is the main ore horizon, is located at the base of the profile. A hematite horizon is located above the limonite, which in the south of the deposit is capped by Eocene freshwater limestones and in the north by a siliceous horizon. The deposit is unusual in lacking a significant saprolite zone with little development of Ni-silicates. The boundary between the limonite zone and serpentinite below is sharp with a marked decrease in concentrations of MgO from 13 to 1 wt.% over a distance of 2 mm representing the ‘Mg discontinuity’. Ni concentrations within goethite, the main ore mineral, reach a maximum of ~3 wt.% near the base of the limonite zone. Silica concentrations are high throughout most of the laterite with up to 80 wt.% silica in the upper portion of some profiles. The combination of a serpentinite protolith and a high water table at Çalda?, in association with an aggressive weathering environment in a tropical climate, resulted in the formation of an oxide-dominated deposit. The precipitation of silica may coincide with a change in climate with silica precipitation linked to an increase in seasonality. Additional variations within profile morphology are attributed to transportation during and after laterite development as a result of faulting, pocket type laterite formation and slumping, each of which produces a contrasting set of textural and geochemical features.

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More information

Published date: July 2009
Keywords: Çalda?, Nickel laterite, Limonite

Identifiers

Local EPrints ID: 66752
URI: http://eprints.soton.ac.uk/id/eprint/66752
ISSN: 0026-4598
PURE UUID: f83ac077-72df-43a4-8525-bfd01b30a7b6
ORCID for Stephen Roberts: ORCID iD orcid.org/0000-0003-4755-6703

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Date deposited: 15 Jul 2009
Last modified: 14 Mar 2024 02:33

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Contributors

Author: Robert Thorne
Author: Richard Herrington
Author: Stephen Roberts ORCID iD

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