Martim Chichorro

New University of Lisbon. Faculdade de Ciências e Tecnologia · Department of Earth Sciences

To the west of the Porto-Tomar Shear Zone, several pre-Mesozoic metasedimentary outcrops belonging to the basement of the Lusitanian Basin are poorly exposed. The traditional view suggests that these units belong to Ossa Morena Zone (OMZ), while more recent models propose the existence of the Finisterra Terrane (TF), considered exotic relative to t...

The nature of the metamorphic belt located west of the Porto-Tomar Shear Zone (central-west Portugal) has been abundantly discussed in terms of its pre-Variscan paleogeography (Moreira et al., 2019; Bento dos Santos et al., 2023). However, not enough attention has been given to its metamorphic evolution during the Variscan Orogeny and ensuing defor...

The Iberian Pyrite Belt (IPB) is a late Devonian – Early Carboniferous world-class polymetallic VMS province that includes significant Cu-(Sn)-Pb-Zn-Ag deposits of massive sulphides and feeder zones. The Aljustrel brownfield region contains one of the highest concentrations of ore in the IPB in 6 known deposits (Gavião, São João, Moinho, Algares, E...

Geochronological data from the pre-Mesozoic basement of the Lusitanian Basement (West of the Porto-Tomar Fault) was obtained. Results show a predominant Cadomian/Pan-African and Eburnean inheritance/source, placing this sector as a peri-Gondwanan domain. However, two major differences can be seen in the data: samples with a clear absence in Mesopro...

Despite the so-called exotic nature of the South Portuguese Zone relatively to the other major domains of the Iberian Massif of peri-Gondwanan affinity, Devonian detrital rocks of the oldest strata in the Iberian Pyrite Belt have a remarkable resemblance with the Ossa-Morena Zone’s Neoproterozoic-Cambrian rocks and the West Meguma’s Cambrian-Ordovi...

This work assessed the age distribution of Cadomian/Pan-African orogenic events (550-590 and 605-790Ma, respectively) in several zones of Iberian Massif by means of detrital and inherited zircon analysis compilation. Detrital zircon age spectra show that throughout the late Neoproterozoic-to-Early Ordovician era (~120Ma sedimentary record), the mai...

The Paleoproterozoic orogenies are among the most significant crustal growth events recorded in Western Gondwana, as depicted by their strong detrital zircon signature into the Gondwanan and peri-Gondwanan sediments. Indeed, the Neoproterozoic–Cambrian sediments of peri-Gondwanan terranes, particularly those in Iberia, Meguma, Avalonia, and Ganderi...

These scientific sessions are focused on the Pan-African and Cadomian Orogenies recorded in North Africa and western Europe across the Ediacaran-Cambrian transition and its bearing in the assembly and demise of Pannotia. Contributions deal with structural, magmatic, provenance sources, palaeomagnetic, sedimentary, chronostratigraphic and radiometri...

In this paper new geochemical, geochronological and isotopic Lu–Hf data from the Siempre Amigos Hills (SA), western Tandilia, Argentina, is presented. Outcrops in this small area include representative lithologies of the basement Río de la Plata craton (RPC) known as Tandilia Terrane. The new geochemical data characterize a heterogeneous Paleoprote...

The geochemical and isotopic (Sm-Nd) features of the Ediacaran-Cambrian siliciclastic series from the Central Iberian Zone and the Iberian Allochthonous Domains indicate a significant paleogeographic change at the northern margin of Gondwana, associated with the development of the Avalonian-Cadomian arc. During the Neoproterozoic, the opening of a...

O Terreno Finisterra (TF) está descrito como um terreno exótico com características paleogeográficas distintas das unidades peri-Gondwanicos típicas do Maciço Ibérico (MI). Diferentes interpretações tectónicas e estruturais das estruturas de primeira ordem, como a Zona de Cisalhamento Porto-Tomar-Ferreira do Alentejo, promovem visões distintas da e...

Various segments of Variscan crust are currently exposed in Iberia in response to successive tectonic events during the Variscan orogeny itself and subsequent extensional and compressive events during the Alpine cycle, all accompanied by surface erosion, and collectively contributing to their exhumation. We review the main characteristics and geody...

A rifting stage initiated the Variscan cycle in NW Gondwana, lasted from Terreneuvian to Early Ordovician times and culminated in opening of the Rheic Ocean. The result of lithospheric stretching was the development of a horst-and-graben structure in the upper crust and formation of basins with sharp variations in thickness and facies of the sedime...

The NW Iberian Allochthon represents the suture of a peri-Gondwanan, Paleozoic ocean formed around the Cambro-Ordovician boundary but having registered renewed spreading during the Lower Devonian. The ocean separated a piece of continental crust detached from NW Gondwana from the northern and northwestern parts of present Africa. The separation was...

Pre-Variscan basement rocks from the Pyrenees provide evidence of several magmatic episodes with complex geodynamic histories from late Neoproterozoic to Palaeozoic times. One of the most significant episodes, consisting of several granitic and granodioritic bodies and volcanic rocks, mostly pyroclastic in nature, dates from the Late Ordovician per...

U-Pb laser ablation inductively coupled plasma mass spectrometry was used for dating zircon grains extracted from four sedimentary and volcano sedimentary rocks of the Montagne Noire encompassing the presumed Ediacaran-Cambrian boundary interval. Magmatic zircon from two samples from the basal and middle parts of the Rivernous Formation (a rhyoliti...

Central Portugal is well known for the existence of Sn-W and Au-Ag mineral occurrences primarily associated with hydrothermal processes. Despite the economic and strategic importance of such occurrences, the detailed geology of this particular region is poorly known and there is an obvious absence of geological mapping at an adequate scale. Remote...

Cryptic Early-to-Main rift-related Cambrian magmatism in Central Iberian and Galiza-Trás-os-Montes zones revealed by U–Pb dating of inherited zircon M. Chichorro1, A.R. Solá2, Cecilio Quesada3, J. J. Álvaro4T. Sánchez-García3, A. Díez Montes5 In: Ordovician Geodynamics: the Sardic Phase in the Pyrenees, Mouthoumet and Montagne Noire massifs (Álvar...

The Cantabro-Iberian Basin: Insights of the Rift- stage revealed by detrital zircon age distributions M. Chichorro1, A.R. Solá2, J. Javier Álvaro3, T. Sánchez-García4, Cecilio Quesada4, Alejandro Díez Montes4 1 GEOBIOTEC, Departamento de Ciências da Terra, Universidade Nova de Lisboa, Portugal; ma.chichorro@fct.unl.pt 2 LNEG, Unidade de Geologia,...

Provenance of Ordovician Armorican quartzite in Iberia: the linkage with West African Craton A. Rita Solá1, Martim Chichorro2, J. Javier Álvaro3, Alejandro Díez Montes4 Teresa Sánchez-García4, Cecilio Quesada4, Solá, A.R., Chichorro, M., Álvaro, J. J., Díez Montes, A., Sánchez-García, T., Quesada, C (2017). Provenance of Ordovician Armorican qu...

The evolution of the rift-drift transition stage in CIZ and GTMZ M. Chichorro1, A.R. Solá2, A. Díez Montes3, J. Javier Álvaro4, T. Sánchez-García3, Cecilio Quesada3, Chichorro, M., Solá, A.R., ., Díez Montes, A., Álvaro, J. J. , Sánchez-García, T., Quesada, C (2017). The evolution of the rift-drift transition stage in CIZ and GTMZ. In: Ordovicia...

The basal allochthonous units of NW and SW Iberia are members of an intra-Gondwana suture zone that spreads across the Iberian Massif and was formed during the collision of Gondwana and Laurussia in the late Paleozoic. This suture zone is made of allochthonous terranes and is currently preserved as a tectonically dismembered ensemble. A multi-proxy...

Laser ablation ICP-MS U-Pb analyses were conducted on detrital zircons of Triassic sandstone and conglomerate from the Lusitanian basin in order to: i) document the age spectra of detrital zircon; ii) compare U-Pb detrital zircon ages with previous published data obtained from Upper Carboniferous, Ordovician, Cambrian and Ediacaran sedimentary rock...

U–Pb geochronological study of zircons from nodular granites and Qtz-diorites comprising part of Variscan high-grade metamorphic complexes in Gredos massif (Spanish Central System batholith) points out the significant presence of Cambro-Ordovician protoliths among the Variscan migmatitic rocks that host the Late Carboniferous intrusive granitoids....

Laser ablation ICP-MS U–Pb analyses have been conducted on detrital zircon of Upper Triassic sandstone from the Alentejo and Algarve basins in southwest Iberia. The predominance of Neoproterozoic, Devonian, Paleoproterozoic and Carboniferous detrital zircon ages confirms previous studies that indicate the locus of the sediment source of the late Tr...

The aim of the present study is to generate a 2D object-based model of the skarn lithologies of the São Pedro das Águias ore deposit (Tabuaço, northern Portugal). Since those lithologies take the form of lens-shaped skarns, and are numerous, thin, conditioned to the deposit structure, and recognized only in the drill-holes, modelling them is a chal...

In the Portuguese context, remote sensing tools have been used with great extent in the most diverse geological subjects. However, with the exception of some works, mainly dating from the eighties and nineties, there are few known study cases that specifically apply remote sensing in the exploration of metallic mineral resources. Due to the fact th...

Detrital zircons from Holocene beach sand and igneous zircons from the Cretaceous syenite forming Cape Sines (Western Iberian margin) were dated using laser ablation - inductively coupled plasma - mass spectrometry. The U-Pb ages obtained were used for comparison with previous radiometric data from Carboniferous greywacke, Pliocene-Pleistocene sand...

The aim of the present study is to use the PCA tool as a geochemical analysis method in order to better define hydrothermal alterations and skarnization zones in complex environments, such as the good example of the São Pedro das Águias skarn deposit (Tabuaço, northern Portugal). The PCA tool allows the reduction of the dimensionality of large and...

In Góis municipality, there are many abandoned mines due to the intense mining exploration of tin and tungsten in past decades. Vale Pião and Senhora da Guia are some of the main mines in the region. The present study proposes a methodology for the exploration of the existing waste rock piles, based on the geochemical, mineralogical and grain size...

For the first time, an Eburnian magmatic event has been identified in the Rehamna Massif (Moroccan Variscan Belt, Western Meseta) located north of the South Meseta fault. The best estimate of the crystallization age of rhyolitic porphyry is given by a weighted mean 207Pb/206Pb age of 2050.6 ± 3 Ma (Rhyacian-Orosirian). The new U–Pb age obtained for...

This paper proposes a multistep approach for creating a 3D stochastic model of gold grades in a complex disseminated auriferous deposit located in the Alentejo region, southern Portugal. The approach involves the following steps: (i) the creation of a 3D low-resolution vector object model of two geological domains that better discriminate gold grad...

The purpose of this study is to simulate W-Sn grades of the São Pedro das Águias skarn ore deposit located in Tabuaço, northern Portugal. This skarn deposit hosts a scheelite and cassiterite mineralization. The proposed methodology begins with the construction of a low-resolution geological model of the skarn lens-shaped, then a morphological model...

CL imaging and U–Th–Pb data for a population of zircons from two of the Évora Massif granitoids (Ossa-Morena Zone, SW Iberia) show that both calc-alkaline granitoids have zircon populations dominated by grains with cores and rims either showing or not showing differences in Th/U ratio, and having ages in the range ca. 350–335 Ma (Early Carboniferou...

Laser ablation U/Pb geochronology data in zircons from 2 syenite rock samples gathered in the Cretaceous Sines Massif were studied. These gave an age range of ca. 87-74 Ma with a predominant probability age peak at ca. 82 Ma. Detail studies based on concordia diagrams pointed to probable 3 crystallization episodic stages at ca. 78, ca. 82 and 86 Ma...

The statistic test Kolmogorov-Smirnov (K-S) used with zircon geochronological data was applied to a sedimentary provenance study of different lithologies outcropping in the Sines Cape vicinity (beaches and sea cliffs) with the objective of testing its discriminative capabilities, having allowed to: i) define what was the contribution of sedimentary...

In SW Iberia there is a basal unconformity where Triassic sandstones overlie previously deformed Carboniferous turbidites. This important stratigraphic boundary records the transition from the final stages of Pangaea’s amalgamation to the initial stages of break-up. U-Pb dating of detrital zircon from Carboniferous greywackes of the South Portugues...

Pliocene–Pleistocene sand of the Alvalade basin was taken from the sea-cliffs of SW Iberia coast for a provenance study using radiometric dating. The U–Pb ages obtained revealed a wide interval ranging from Cretaceous to Archean, with predominance of Paleozoic, Neoproterozoic and Cretaceous zircon ages. Cretaceous ages interpreted to indicate a Sin...

El Cerro Siempre Amigos está constituido por una porción del basamento ígneo-metamórfico Paleoproterozoico que aflora como parte de las Sierras de Azul, en Tandilia, bajo la denominación de Complejo Buenos Aires y formando parte del Cratón del Río de La Plata. La región muestra rasgos de milonitización causada por un evento de deformación similar a...

Geochronological comparisons of large datasets are facilitated by the use of structured databases. This paper reports the ongoing development of CHRONIBERIA, a geochronological GIS database that will provide access to zircon U–Pb age datasets from Iberia. The database will also integrate relevant distinct datasets from other correlative regions aro...

This study makes a comparison between the populations of detrital zircons of the Cambrian sandstones from the Ossa–Morena Zone (OMZ) and the Ordovician quartzites from the southern domains of the Central Iberian Zone (S-CIZ) to identify the sediment sources during the development of North Gondwana basins (southwestern Iberia). The U–Pb results obta...

U–Pb dating of detrital zircons from the lower Palaeozoic siliciclastic rocks of southwestern Iberia (the Ossa–Morena Zone or OMZ: comprising the Fatuquedo, Ossa, Colorada, and Terena formations) shows that sedimentation during the middle–late Cambrian to Early Devonian was marked by slight variations in the source areas, involving the denudation o...

U–Pb geochronology of zircons provides essential data for determining the precise ages and temporal relationships of late Palaeozoic volcanic activity and contributes to improving knowledge of the stratigraphy of the Southern Pyrenees (ca. 304 Ma to ca. 282 Ma, upper Carboniferous–lower Permian). The reported ages for the Erill-Castell, Estac, Cadí...

New petrological and U–Pb zircon geochronological information has been obtained from intrusive plutonic rocks and migmatites from the Cap de Creus massif (Eastern Pyrenees) in order to constrain the timing of the thermal and tectonic evolution of this northeasternmost segment of Iberia during late Palaeozoic time. Zircons from a deformed syntectoni...

In the Southern Pyrenees there are Upper Carboniferous–Lower Permian sedimentary basins with a significant volume of volcanic material derived from explosive eruptions (rhyolitic ignimbrites and andesitic flows). These basins are spatially associated with granodiorites and dacitic dykes emplaced in Variscan basement rocks. U–Pb SHRIMP dating of zir...

U–Pb dating of detrital zircons from the Carboniferous turbidites of southwestern Iberia (the Cabrela, Mértola, Mira, and Brejeira formations) shows that synorogenic sedimentation during the Carboniferous was marked by significant variations in the source areas, involving the denudation of different crustal blocks and a break in synorogenic volcani...

The determination of U–Pb ages from detrital zircons of sedimentary rocks using LA–ICP–MS has been widely used to develop studies of provenance analysis. A problem that frequently arises is to find a population that appears to be noncomplex despite several perceptible age peaks in their spectrum. These peaks are qualitatively defined through diagra...

The Late Triassic basins of SW Portugal were filled with continental detrital deposits dominated by sandstones and some interbedded conglomerates and mudstones. In this study, detrital zircons were separated from samples of the Upper Triassic sandstones of the Silves Formation collected in the Alentejo and Algarve basins. Conventional methods of se...

This study makes a comparison of detrital-zircon age populations from upper Ediacaran greywackes of the Ossa–Morena Zone (OMZ) with those from the southern domains of the Central Iberian Zone (S-CIZ). The results reveal that the main difference between the age spectra of both populations of detrital zircon is the Neoproterozoic, in particular the C...

A potassic magmatic association in the Zagros hinterla bnd of the Tethyan orogen in Iran is identified and characterized for relevant geochronologic and petrologic features. New data, including a combination of field relations, U-Pb zircon geochronology and rock geochemistry, come from seven plutons (Khankandi, Shaivar-Dagh, Yuseflu, Mizan, Saheb-D...

Two distinct Cambrian magmatic pulses are recognized in the Ossa-Morena Zone (SW Iberia): an early rift-(ER) and a main rift-related event. This Cambrian magmatism is related to intra-continental rifting of North Gondwana that is thought to have culminated in the opening of the Rheic Ocean in Lower Ordovician times. New data of whole-rock geochemis...

This study combines geochemical and geochronological data in order to decipher the provenance of Carboniferous turbidites from the South Portuguese Zone (SW Iberia). Major and trace elements of 25 samples of graywackes and mudstones from the Mértola (Visean), Mira (Serpukhovian), and Brejeira (Moscovian) Formations were analyzed, and 363 U-Pb ages...

In southern Europe and the western Mediterranean, Permo-Carboniferous magmatism is well represented in areas of Iberia, the Alps, Sardinia and the Balkan Peninsula. In Iberia, the magmatism that has been related to the Variscan orogeny is associated with syn-orogenic events at ca. 350-315 Ma and post-orogenic at ca. 310-295 Ma. In the southern Pyre...

This study deals with the interaction between deformation and magmatism in mid-to deep-crustal domains. The relation is analysed between migmatites and shear zones and the spatial distribution of leucogranitoid veins and dykes running through a footwall migmatite system, and reaching a transtensional shear zone operated under amphibolite-to greensc...

In this preliminary study of provenance analysis, Neogene sandstones and conglomerates of the Alvalade Basin were sampled from sea cliffs in the vicinity of the Sines Cape (southwestern Portuguese coast). Detrital zircons were extracted by conventional methods of particle size separation including magnetism and heavy liquids. Detrital zircons were...

Export Date: 11 October 2012, Source: Scopus, doi: 10.1016/j.gr.2012.03.010, Language of Original Document: English, Correspondence Address: Pereira, M.F.; IDL, Departmento de Geociências, ECT, Universidade de Évora, Apartado 94, 7001-554 Évora, Portugal; email: mpereira@uevora.pt, References: Aramburu, C., Méndez-Bedia, I., Arbizu, M., García-Lope...

The Estremoz Anticline in the Ossa-Morena Zone (SW Iberia) includes upper Ediacaran detrital rocks unconformably overlain by lower Cambrian detrital and carbonate rocks. The spectra of detrital zircon U–Pb ages dominated by Cryogenian and Ediacaran ages (with a typical gap in Mesoproterozoic ages) of the upper Ediacaran greywackes and lower Cambria...

New U–Pb and 40Ar–39Ar geochronology and structural data from high- to medium grade metamorphic shear zones of the Ossa-Morena Zone, and structural data from Early Carboniferous basins (Ossa-Morena Zone and South-Portuguese Zone), place additional constraints on the Variscan tectonics in SW Iberia. A zircon U–Pb age of 465 ± 14 Ma (Middle Ordovicia...

U–Pb geochronology of detrital zircon from Late Ediacaran (Beiras Group greywackes) and Early Ordovician (Sarnelhas arkosic quartzites and Armorican quartzites of Penacova) sedimentary rocks of the southwest Central Iberian Zone (SW CIZ) constrain the evolution of northern Gondwana active-passive margin transition. The LA-ICP-MS U–Pb data set (375...

U–Pb SHRIMP geochronology on zircon extracted from a granite, a sandstone and a quartzite of the SW Iberian Massif (Ossa-Morena Zone), was used in order to investigate the contribution of Late Neoproterozoic (Cadomian) tectonothermal history to the crustal growth of northern Gondwana. The analysed Cambrian rocks were sampled along the southern marg...

Two very different periods of magma emplacement in the crust of the Ossa-Morena zone (early and main events) in SW Iberia have been previously interpreted to record a Cambrian/Early Ordovician rifting event that is thought to have culminated in the opening of the Rheic Ocean during the Early Ordovician. New stratigraphic, petrographic, geochemical...

This provenance study is mainly based on new whole-rock geochemistry data but also involves detrital zircon geochronology. More specifically, this study investigates the Early Mesozoic denudation of a Late Paleozoic mountain range, and the coeval development of basins during Pangea break-up in SW Iberia. The relations with past dynamic Earth events...

The Variscan belt of Western and Central Europe was formed by the oblique subd