Rare earth element characteristics and K–Ar ages of the Band Ziarat ophiolite complex, southeastern Iran

The Band Ziarat complex of southeastern Iran is located on the western boundary of the Jaz Murian depression and is bounded by two major fault systems. The principal rock units of this complex are a gabbro sequence that includes low-and high-level cumulate gabbros, a late intrusive sequence that consists of diorite and plagiogranite, and a volcanic sequence that includes diabase dikes and a lesser amount of basaltic lava. Mantle rocks are virtually absent because of the presence of the two bounding fault systems, but we consider the complex to be an ophiolite in nature. Rare earth element (REE) whole-rock data clearly differentiate the classic ophiolitic lithologies for the crustal rocks in this complex. Based on the REE data, there are two distinct types of basalt present at Band Ziarat: (i) those that formed from an initial basaltic melt with a light rare earth element (LREE) enriched signature (similar to intraplate basalts), and (ii) those that have LREE-depleted patterns (similar to normal mid-ocean-ridge basalts). The data also suggest (i) that the gabbros are accumulates and were derived from a source slightly enriched in LREE, with fractionation controlled by removal of clinopyroxene or hornblende and plagioclase, and (ii) that the late intrusive rocks as well as a majority of the diabase dikes are cogenetic and were derived from the same LREE-enriched source. K–Ar ages ranging from 134 ± 4 to 146 ± 5 Ma for low-level gabbros and from 121 ± 4 to 130 ± 4 Ma for high-level gabbros were measured on five hornblende and two whole-rock samples, which suggests that these rocks may have formed early in the Cretaceous period.

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Quantitative trace-element modelling of the crystallization history of the Kinojévis and Blake River groups, Abitibi Greenstone Belt, Ontario

Canadian Journal of Earth Sciences ◽

10.1139/e89-115 ◽

1989 ◽

Vol 26 (7) ◽

pp. 1356-1367 ◽

Cited By ~ 23

Author(s):

A. D. Fowler ◽

L. S. Jensen

Keyword(s):

Rare Earth ◽

Rare Earth Element ◽

Fractional Crystallization ◽

Earth Element ◽

Calc Alkaline ◽

Quantitative Modelling ◽

Ti Oxides ◽

History Of ◽

High Level ◽

Ree Patterns

The Archean tholeiitic Kinojévis suite is characterized by an iron-enrichment trend and abundant Fe–Ti oxides in its evolved basalts, andesites, and rhyolites. The rare-earth-element (REE) patterns of the suite remain flat from the basalts through to the rhyolites, with the development of small, negative Eu anomalies. Quantitative modelling of the trace elements from little-altered samples is consistent with the mineralogy, suggesting that the suite was produced through fractional crystallization of olivine, pyroxene, plagioclase, and Fe–Ti oxides. The evolved rhyolites are interpreted as having developed by greater than 90% fractional crystallization in a high-level magma chamber.The calc-alkaline Blake River Group conformably overlies the Kinojévis rocks and is characterized by enrichment in alkalis and silica. The REE patterns are light rare-earth-element (LREE) enriched, and the felsic rocks have prominent negative Eu anomalies. Geochemical modelling shows that the suite could have developed either through fractional crystallization dominated by plagioclase and clinopyroxene or by assimilation of tonalite, coupled with fractional crystallization.

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Rare earth element–SiO2 systematics of mid-ocean ridge plagiogranites and host gabbros from the Fournier oceanic fragment, New Brunswick, Canada: a field evaluation of some model predictions

Contributions to Mineralogy and Petrology ◽

10.1007/s00410-012-0732-x ◽

2012 ◽

Vol 164 (2) ◽

pp. 191-204 ◽

Cited By ~ 19

Author(s):

James G. Brophy ◽

Xiaofei Pu

Keyword(s):

Rare Earth ◽

New Brunswick ◽

Rare Earth Element ◽

Earth Element ◽

Field Evaluation ◽

Mid Ocean Ridge ◽

Model Predictions ◽

Ocean Ridge

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The Jurassic–Early Cretaceous basalt–chert association in the ophiolites of the Ankara Mélange, east of Ankara, Turkey: age and geochemistry

Geological Magazine ◽

10.1017/s0016756817000401 ◽

2017 ◽

Vol 155 (2) ◽

pp. 451-478 ◽

Cited By ~ 10

Author(s):

VALERIO BORTOLOTTI ◽

MARCO CHIARI ◽

M. CEMAL GÖNCÜOGLU ◽

GIANFRANCO PRINCIPI ◽

EMILIO SACCANI ◽

...

Keyword(s):

Rare Earth ◽

Rare Earth Element ◽

Early Cretaceous ◽

Middle Jurassic ◽

Late Jurassic ◽

Earth Element ◽

Volcanic Rocks ◽

Heavy Rare Earth Element ◽

Rock Types ◽

Ocean Ridge

AbstractThis study is focused on slide blocks including oceanic lavas associated with pelagic sediments within the eastern part of the Ankara Mélange. A detailed petrological characterization of the volcanic rocks and a detailed biochronological investigation of the associated radiolarian cherts in eight sections (east of Ankara) was carried out. The volcanic rocks are largely represented by basalts and minor ferrobasalts and trachytes. They show different geochemical affinities and overlapping ages including: (a) Late Jurassic – Early Cretaceous garnet-influenced MORB (middle late Oxfordian to late Kimmeridgian–early Tithonian and early–early late Tithonian; late Valanginian–early Barremian); (b) Early Cretaceous enriched-MORB (middle late Barremian–early early Aptian; Valanginian to middle Aptian–early Albian); (c) Middle Jurassic plume-type MORB (early–middle Bajocian to late Bathonian–early Callovian); (d) Late Jurassic – Early Cretaceous alkaline basalts (middle–late Oxfordian to late Kimmeridgian–early Tithonian; late Valanginian to late Hauterivian). All rock types show a clear garnet signature, as testified to by their high MREE/HREE (middle rare earth element/heavy rare earth element) ratios. The coexistence of chemically different rock types from Middle Jurassic to Early Cretaceous times suggests that they were formed in a mid-ocean ridge setting from partial melting of a highly heterogeneous mantle characterized by the extensive occurrence of OIB-metasomatized portions, which were likely inherited from Triassic mantle plume activity associated with the continental rift and opening of the Neotethys branch.

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