Geology, petrography and mineral chemistry of iron oxide-apatite occurrences (IOA type), western sector of the neoproterozoic Santa Quiteria magmatic arc, Ceará northeast, Brazil

2019 ◽  
Vol 112 ◽  
pp. 103024
Author(s):  
Clóvis Vaz Parente ◽  
César Ulisses Vieira Veríssimo ◽  
Nilson Francisquini Botelho ◽  
Roberto Perez Xavier ◽  
Jacqueline Menez ◽  
...  
Keyword(s):  
Iron Oxide ◽  
Mineral Chemistry ◽  
Northeast Brazil ◽  
Magmatic Arc ◽  
Western Sector

scholarly journals A preserved early Ediacaran magmatic arc at the northernmost portion of the Transversal Zone central subprovince of the Borborema Province, Northeastern South America

2016 ◽  
Vol 46 (4) ◽  
pp. 491-508 ◽  
Author(s):  
Benjamim Bley de Brito Neves ◽  
◽  
Edilton José dos Santos ◽  
Reinhardt Adolfo Fuck ◽  
Lauro César Montefalco Lira Santos ◽  
...  
Keyword(s):  
Granitic Rocks ◽  
Lower Plate ◽  
Low Grade ◽  
Northeast Brazil ◽  
The South ◽  
Magmatic Arc ◽  
Continental Plate ◽  
Borborema Province ◽  
Northern Portion ◽  
Fold Belts

ABSTRACT: Magmatic arcs are an essential part of crust-forming events in planet Earth evolution. The aim of this work was to describe an early Ediacaran magmatic arc (ca. 635-580 Ma) exposed in the northernmost portion of the Transversal Zone, central subprovince of Borborema Province, northeast Brazil. Our research took advantage of several syntheses by different authors, including theses and dissertations, carried out on magmatic rocks of the study area for the last 30 years. The ca. 750 km long and up to 140 km wide arc, trending ENE-WSW, is preserved to the south of the Patos Lineament, between 35º15' and 42º30'W and 7º15' and 8ºS. About 90 different stocks and batholiths of I-type granitic rocks were mapped along this orogenic zone, preferentially intruding low-grade schists of the Cryogenian-Ediacaran Piancó-Alto Brígida (SPAB) belt. Three igneous supersuites are recognized: a) epidote-bearing granodiorites and tonalites ("Conceição" type); b) high-K calc-alkaline granites ("Itaporanga" type); c) biotite granodiorites of trondhjemite affinity ("Serrita" type). A fourth group of peralkalic and shoshonitic rocks occurs to the south of the previous ones, reflecting special tectonic conditions. NNE-SSW trending Paleoproterozoic fold belts, surrounding Archean nuclei, characterize the continental part of the northern lower plate. The oceanic fraction of this lower plate was recycled by subduction and scarce remnants of which may be seen either within the enclosing low-grade schists or as xenoliths within the arc intrusions. The upper continental plate presents WSW-ENE structural trends and is composed of Neoproterozoic fold belts and Paleoproterozoic reworked basement inliers. Available data bear clear evidence of an Ediacaran magmatic arc built at the northern portion of the Transversal Zone in the Borborema Province, northeast Brazil.

Late Paleoproterozoic granulite-facies metamorphism in the North Altyn Tagh area, southeastern Tarim craton: Pressure-temperature paths, zircon U-Pb ages, and tectonic implications

2019 ◽  
Vol 131 (9-10) ◽  
pp. 1591-1606 ◽  
Author(s):  
Hailin Wu ◽  
Wenbin Zhu ◽  
Rongfeng Ge
Keyword(s):  
Granulite Facies ◽  
Mineral Chemistry ◽  
Crustal Thickening ◽  
Granulite Facies Metamorphism ◽  
Magmatic Arc ◽  
Collisional Orogen ◽  
The North ◽  
Altyn Tagh ◽  
Facies Metamorphism ◽  
Tarim Craton

Abstract Granulite occupies the root of orogenic belts, and understanding its formation and evolution may provide critical information on orogenic processes. Previous studies have mainly focused on garnet-bearing high-pressure and medium-pressure granulites, whereas the metamorphic evolution and pressure-temperature (P-T) paths of garnet-absent, low-pressure granulites are more difficult to constrain. Here, we present zircon U-Pb ages and mineral chemistry for a suite of newly discovered two-pyroxene granulites in the North Altyn Tagh area, southeastern Tarim craton, northwestern China. Conventional geothermobarometry and phase equilibrium modeling revealed that these rocks experienced a peak granulite-facies metamorphism at T = 790–890 °C and P = 8–11 kbar. The mineral compositions and retrograde symplectites record a clockwise cooling and exhumation path, possibly involving near-isothermal decompression followed by near-isobaric cooling. Zircon U-Pb dating yielded a ca. 1.97 Ga metamorphic age, which likely represents the initial cooling age, based on Ti-in-zircon thermometry. Combined with regional geological records, we interpret that these granulites originated from the basement rocks of a late Paleoproterozoic magmatic arc that was subsequently involved in a collisional orogen in the southern Tarim craton, presumably related to the assembly of the Columbia/Nuna supercontinent. The clockwise P-T paths of the granulites record crustal thickening and burial followed by crustal thinning and exhumation in the upper plate of the collisional orogen. Our data indicate that the initial exhumation of this orogen probably occurred no later than ca. 1.97 Ga, which is supported by widespread 1.93–1.85 Ga postorogenic magmatism in this area.

Fault reconstructions using aeromagnetic data in the Great Bear magmatic zone, Northwest Territories, Canada

2014 ◽  
Vol 51 (10) ◽  
pp. 927-942 ◽  
Author(s):  
Nathan Hayward ◽  
Louise Corriveau
Keyword(s):  
Iron Oxide ◽  
Vertical Axis ◽  
Fault System ◽  
Aeromagnetic Data ◽  
Block Rotation ◽  
Magmatic Arc ◽  
The North ◽  
Copper Gold ◽  
Great Bear Magmatic Zone ◽  
Transcurrent Faults

The Great Bear magmatic zone, located in Wopmay orogen, is a 1.875–1.84 Ga belt, 450 km long by 100 km wide of volcanic and allied plutonic rocks interpreted as a Paleoproterozoic magmatic arc. The belt, which contains economically important mineralization, was folded and subsequently cut by a swarm of northeast-striking transcurrent faults, which are part of a regional conjugate fault system interpreted to result from terminal collision of the Nahanni – Fort Simpson terrane. Fault reconstructions based on the interpretation of aeromagnetic data and geological maps provide first-order models of deformation mechanisms associated with, and the configuration of the Great Bear magmatic zone prior to, its dissection by northeast-striking transcurrent faults. The models show that vertical axis block rotation (plane strain) of ∼4.5° can explain fault offsets in the south, but that greater rotation is required to explain many of the displacements in the north. However, offsets on transcurrent faults that border the Camsell River district are greater than can be explained by vertical axis block rotation model alone and may include a component of Mesoproterozoic contractional deformation associated with the Racklan–Forward orogeny. Following reconstruction, iron oxide alkali alteration and associated mineralization, which pre-date transcurrent faulting, form a pair of northerly trending zones on the east and west margins of the belt. We suggest that these zones, whose exposure is related to broad synclinal folding of some of the oldest rocks in the Great Bear magmatic zone, are where iron oxide copper–gold (IOCG)-targeted exploration efforts should be focused on these areas in both outcrop and subcrop.

Mineral chemistry of ore and hydrothermal alteration at the Sossego iron oxide–copper–gold deposit, Carajás Mineral Province, Brazil

2008 ◽  
Vol 34 (3) ◽  
pp. 317-336 ◽  
Author(s):  
Lena Virgínia Soares Monteiro ◽  
Roberto Perez Xavier ◽  
Murray W. Hitzman ◽  
Caetano Juliani ◽  
Carlos Roberto de Souza Filho ◽  
...  
Keyword(s):  
Iron Oxide ◽  
Gold Deposit ◽  
Hydrothermal Alteration ◽  
Mineral Chemistry ◽  
Carajás Mineral Province ◽  
Copper Gold

scholarly journals Crystallization Conditions and Petrogenetic Characterization of Metaluminous to Peraluminous Calc-Alkaline Orogenic Granitoids from Mineralogical Systematics: The Case of the Cambrian Magmatism from the Sierra de Guasayán (Argentina)

Minerals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 166
Author(s):  
Priscila S. Zandomeni ◽  
Juan A. Moreno ◽  
Sebastián O. Verdecchia ◽  
Edgardo G. Baldo ◽  
Juan A. Dahlquist ◽  
...  
Keyword(s):  
Mineral Chemistry ◽  
Quartz Diorite ◽  
Common Mechanism ◽  
Chemical Compositions ◽  
Magmatic Arc ◽  
Hybrid Nature ◽  
Eastern Sierras Pampeanas ◽  
Microgranular Enclaves ◽  
Mafic Microgranular Enclaves ◽  
Crystallization Conditions

The Sierra de Guasayán (Eastern Sierras Pampeanas, Argentina) is formed by low to medium grade metamorphic rocks intruded by Cambrian metaluminous (La Soledad quartz-diorite), slightly peraluminous (Guasayán, El Escondido and El Martirizado granodiorite plutons), and strongly peraluminous (Alto Bello granodiorite) granitoids of the Pampean magmatic arc. Chemical compositions of amphibole, plagioclase, biotite, and titanite indicate that these granitoids were emplaced at low pressure (mostly <3 kbar) and temperature (<770 °C) under oxidizing conditions (QFM + 1 and QFM + 2), which are similar to the emplacement conditions reported for other granites of the Pampean magmatic arc. Mineral assemblages and whole-rock and mineral chemistry of the granitoids from the Sierra de Guasayán indicate an I-type affinity for the La Soledad quartz-diorite (amphibole, biotite, and titanite), S-type affinity for the Alto Bello granodiorite (biotite, muscovite, cordierite, and sillimanite), and a hybrid nature for the main Guasayán and El Escondido plutons (biotite, monazite, and magnetite). This hybrid nature is supported by the presence of abundant mafic microgranular enclaves and rapakivi texture and by published zircon Hf-isotope data (εHfi ranging from −4.76 to −0.12). This suggests, in turn, the involvement of hybridization in the genesis of these granitoids, which seems to be a common mechanism operating in the Pampean magmatic arc.

Paleozoic Magmatism and Mineralization Potential of the Sanchakou Copper Deposit, Eastern Tianshan, Northwest China: Insights from Geochronology, Mineral Chemistry, and Isotopes

2021 ◽  
Author(s):  
Fang-Fang Zhang ◽  
Yin-Hong Wang ◽  
Jia-Jun Liu ◽  
Chun-Ji Xue ◽  
Jian-Ping Wang ◽  
...  
Keyword(s):  
Late Stage ◽  
Secondary Ion Mass Spectrometry ◽  
Copper Deposit ◽  
High Water ◽  
Mineral Chemistry ◽  
Northwest China ◽  
Magma Ascent ◽  
Eastern Tianshan ◽  
Magmatic Arc ◽  
Mineralization Potential

Abstract The Sanchakou Cu deposit is located in the eastern section of the Dananhu magmatic arc in the Eastern Tianshan orogenic belt, northwest China. Sanchakou is hosted by quartz diorite and granodiorite intrusions. Chalcopyrite and bornite are the dominant ore minerals and occur as disseminations, patches, veins, and veinlets. Secondary ion mass spectrometry (SIMS) U-Pb dating of zircons shows that the ore-bearing intrusions were emplaced at ca. 435–432 Ma, recording the early subduction of the Paleo-Tianshan oceanic plate. The enrichment in large ion lithophile elements (LILEs), depletion in high field strength elements (HFSEs), and moderate Mg# values, together with mantle-like bulk Sr-Nd and zircon Hf-O isotope signatures (δ18O = 4.0–5.3‰), suggest that they were generated from partial melting of metasomatized mantle materials by subducted slab fluids. In situ S and whole-rock Pb isotope results imply that the Sanchakou diorite magmas provided ore-forming components (S and metals), with additional minor metals (e.g., Cu and Pb) sourced from crustal components beneath the Dananhu arc. The redox state of diorite magmas ranges from initial high fO2 (&gt;FMQ + 2, where FMQ is the fayalite-magnetite-quartz buffer) to relatively low fO2 (&lt;FMQ + 2) upon magma ascent and cooling. The late-stage less oxidized magma compositions are consistent with the presence of magmatic sulfides in primary plagioclase and magnetite. Estimates of water-sulfur-chlorine contents in magma using plagioclase, amphibole, and apatite compositions reveal that the diorite magmas had high water (&gt;7 wt %), normal S (8–393 ppm), and systematically low Cl (38–1,100 ppm) contents. A constant and favorable elevated magma oxidation state appears critical for generating an economic porphyry Cu deposit. Additionally, Cl melt concentrations may be a key factor that controlled metal fertility of the deposits in the Eastern Tianshan, although the mineralization potential may also relate to depth of emplacement of the hydrothermal system. The anomalous presence of stellerite with chalcopyrite in late-stage veins indicates that original porphyry-style mineralization at Sanchakou underwent deformation-related modification after its formation.

Gemologic Characterization and Mineral Chemistry of Blue Tourmalines from the Peg-Matitic Body of Bom Jesus, Banabuiú - Ceará, Northeast Brazil

2008 ◽  
Vol 19 (2) ◽  
pp. 317-320
Author(s):  
G.M. Rosa ◽  
G.M.S. Hamelak ◽  
M.N. Lima ◽  
A.A. Carneiro ◽  
D.M. Nascimento ◽  
...  
Keyword(s):  
Mineral Chemistry ◽  
Northeast Brazil

scholarly journals Mineral chemistry of tantalate species new in the Borborema Pegmatitic Province, Northeast Brazil

2005 ◽  
Vol 77 (1) ◽  
pp. 169-182 ◽  
Author(s):  
Hartmut Beurlen ◽  
Dwight R. Soares ◽  
Rainer Thomas ◽  
Lucila E. Prado-Borges ◽  
Cláudio de Castro
Keyword(s):  
Mineral Chemistry ◽  
Northeast Brazil ◽  
Small Areas ◽  
The Core ◽  
Reverse Trend ◽  
Geochemical Indicators ◽  
Microprobe Data ◽  
Normal Trend

Tantalate samples, supposedly of the columbite group, were collected in the Borborema Pegmatitic Province, aiming to test the Mn/(Mn+Fe) and Ta/(Ta+Nb) ratios as geochemical indicators of pegmatite fractionation. Surprisingly, preliminary microprobe data allowed recognizing some species, so far unknown in the Province, namely titanian ixiolite, fersmite, brannerite, strüverite, natrobistantite, plumbo- and stibiomicrolite, plumboand uranpyrochlore. The identification of these exotic tantalates with unusual composition, in addition to its distribution in several pegmatites, far from the classical Alto do Giz and Seridozinho pegmatites, indicate that the elevated degree of fractionation is not restricted to these two occurrences but may be reached in other pegmatite areas of the Province. It indicates also that this degree of fractionation may be very variable between pegmatites in small areas. The zoning patterns observed in the titanian ixiolite, with Ti and Nb enrichment at the borders at expense of Ta enriched in the core, are also quite unusual and reverse in comparison with the normal trend of progressive Ta and Mn enrichment in tantalates with the degree of fractionation. A similar "reverse" trend was observed in titanian wodginite of petalite/pollucite bearing pegmatites of the Separation Rapids Province in Ontario, Canada.

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