Leech, Desmond P. (2003) Iron-oxide mineralisation magmatic processes and lineament development associated with deformation along the Atacama Fault System, Huasco Province, northern Chile. (PhD thesis), Kingston University.Full text not available from this archive.
In this thesis spatial and temporal relationships are established between faulting and both pluton emplacement and iron-oxide mineralisation in the Huasco Province (28° to 29°S) of northern Chile. Landsat TM data are used to show a bimodal distribution of lineament orientations within the Chilean continental margin. NW-trending lineaments are most common in terms of both frequency and length. A subordinate set of elongate, interconnected NNE-trending lineaments belong to the NNE-trending Atacama Fault System (AFS) and the Chanarcillo fold¬and-thrust belt. Zones of brittle and ductile deformation are present along strands of the AFS. Early Cretaceous (ca. 120Ma) pluton emplacement occurred during transtensional deformation, and was facilitated by a combination of roof-uplift and floor-depression mechanisms along the AFS. REE concentrations in the plutonic complexes are moderately enriched, show negative Eu anomalies and moderate LREE: HREE ratios. These data imply fractionation from a plagioclase-rich, garnet-poor source. Iron-oxide mineral deposits are located at intersections between NW and NNE-trending structures. Mineralising fluids were trapped in and adjacent to NW and NNE-trending faults in the Los Colorados and Algarrobo iron-oxide deposits. In these deposits, magnetite [delta][sup]18(SMOW) values range from between +0.04 and +1.83 per mil. Coeval apatite has [delta][sup]18O(SMOW) values ranging from +5.28 to +8.32 per mil. [delta][sup]34(CDT) values from pyrite intergrown with magnetite range from -2.91 to +1.94 per mil. These data suggest that the fluids and metals responsible for mineralisation have close magmatic-hydrothermal affinities. Considerable volume increases <37%) are associated with mineralisation. Alteration that post¬dates mineralisation is associated with changing oxidation-state during cooling of the hydrothermal system. Fluid inclusion studies show that the late fluids belonged to a mixed H[sub]20-NaCI-CaCI[sub]2 system. The data presented here can be specifically applied to future exploration in the Chilean Iron Belt, and have a general relevance to the understanding' of the evolution of iron-oxide-(copper-gold) deposits.
|Item Type:||Thesis (PhD)|
|Physical Location:||This item is held in stock at Kingston University Library.|
|Research Area:||Earth systems and environmental sciences|
|Depositing User:||Automatic Import Agent|
|Date Deposited:||09 Sep 2011 21:39|
|Last Modified:||30 May 2014 13:59|
Actions (Repository Editors)
|Item Control Page|