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Southern New Brunswick consists of a collage of fault-bounded belts of Late Neoproterozoic igneous and metamorphic rocks, early Paleozoic sedimentary, metamorphic and igneous units, and overlying Carboniferous and locally Triassic sedimentary rocks. The area also contains the boundary between Avalonia and Ganderia as interpreted in the northern Appalachian orogen. New detrital zircon ages reported here provide improved understanding of depositional ages and provenance of diverse Neoproterozoic to Carboniferous rocks in this complex area. Detrital zircon data from samples with Neoproterozoic maximum depositional ages indicate a dominantly Gondwanan provenance with strong influence from the Amazonian craton. However, quartzite from The Thoroughfare Formation on Grand Manan Island contains dominanly 2 Ga zircon grains, consistent with derivation from the West African craton. The age spectrum is similar to that of the Hutchins Island Quartzite in the Isleboro block in Penobscot Bay, Maine, strengthening the possibility of correlation between the two areas. Cambrian samples also show prominent peri-Gondwanan provenance with strong influence from F.diacaran to early Cambrian arc magmatism. The maximum depositional ages of these samples are consistent with previous interpretations of Cambrian ages based on fossil correlations and field data. A Carboniferous sample from Avalonia shows a significant contribution from Devonian magmatism as the youngest detrital component, although its depositional age based on field relationships is Carboniferous. The results exemplify the need to integrate multiple datasets in making interpretations from detrital zircon data. Le sud du Nouveau-Brunswick est constitue d'un collage de ceintures delimitees par des failles de roches ignees et metamorphiques du Neoproterozoique tardif, d'unites sedimentaires, metamorphiques et ignees du Paleozoique precoce, ainsi que de roches sedimentaires sus-jacentes du Carbonifere et, par endroits, du Trias. Le secteur comprend egalement la frontiere etablie entre Avalonia et Ganderia selon son interpretation a l'interieur de la partie septentrionale de l'orogene des Appalaches. De nouvelles datations de zircon detritique rapportees ici permettent une meilleure comprehension des ages sedimentaires et de la provenance des diverses roches neoproterozoiques a carboniferes dans ce secteur complexe. Les donnees relatives au zircon detritique obtenues des echantillons faisant etat d'ages sedimentaires remontant au maximum au Neoproterozoique signalent une provenance en predominance gondwanienne avec une forte influence du craton amazonien. Le quartzite de la Formation The Thoroughfare sur l'ile Grand Manan renferme toutefois predominament des grains de zircon de 2 Ga, ce qui correspond a une derivation du craton de l'Afrique occidentale. Le spectre de l'age est similaire a celui du quartzite de l'ile Hutchins a l'interieur du bloc Isleboro dans la baie Penobscot, au Maine, ce qui renforce la possibilite d'une correlation entre les deux secteurs. Les echantillons du Cambrien font eux aussi etat d'une provenance perigondwanienne prononcee, marquee d'une forte influence d'un magmatisme d'arc de l'Ediacarien au Cambrien precoce. Les ages sedimentaires maximaux de ces echantillons correspondent aux interpretations anterieures des datations du Cambrien basees sur des correlations de fossiles et des donnees d'echantillonnage sur le terrain. Un echantillon du Carbonifere provenant d'Avalonia revele une contribution prononcee du magmatisme devonien a titre d'element detritique le plus recent, mais son age sedimentaire le situe au Carbonifere d'apres les relations etablies sur le terrain. Les resultats illustrent la necessite d'une integration de plusieurs ensembles de donnees pour effectuer des interpretations a partir de donnees provenant de zircon detritique. [Traduit par la redaction], INTRODUCTION AND GEOLOGICAL SETTING Southern New Brunswick consists of a complex assemblage of three fault-bounded belts of mainly Neoproterozoic rocks with minor Paleozoic rocks termed (from southeast to northwest) Caledonia, [...]

The Almond Road Group in the northeastern New River belt comprises two formations: the basal Snider Mountain Formation contains orthoquartzite, feldspathic quartzite, and quartzite pebble conglomerate; the gradationally overlying Ketchum Brook Formation is composed of feldspathic sandstone, laminated dark siltstone and shale, overlain by mafic lithic tuffs and basaltic flows. The Almond Road Group overlies latest Ediacaran to earliest Cambrian (early Fortunian) pyroclastic, volcaniclastic, and epiclastic rocks of the Belleisle Bay Group. Based in part on this relationship, the Almond Road Group was thought to be Early Cambrian, although an upper age limit had never been determined. A U-Pb (zircon) age of 475 [+ or -] 2 Ma for the West Scotch Settlement porphyry, a small felsic hypabyssal intrusion emplaced into the Ketchum Brook Formation, demonstrates that the Almond Road Group is no younger than Early Ordovician (early Floian) age. Its age is further constrained by LA ICP-MS detrital zircon data from a basal quartzite in the Snider Mountain Formation. Results show a dominant peak in the Ediacaran (ca. 575 Ma), with the youngest coherent cluster of ages at ca. 530-520 Ma. Together these data support a Cambrian age for the quartz-rich Almond Road Group and its platformal relationship to Ganderia. Le groupe d'Almond Road, dans la ceinture nord-est de New River, comporte deux formations : la formation basale de Snider Mountain, qui contient de l'orthoquartzite, du quartzite feldspathique et un conglomérat de cailloux de quartz; la formation de Ketchum Brook, progressivement superposée et composée de grès feldspathique, de siltite feuilleté foncé et de schiste superposé de tuf lithique mafique et de coulées basaltiques. Le groupe d'Almond Road repose sur des roches pyroclastiques, volcanoclastiques et épiclastiques allant de l'Édiacarien tardif au Cambrien précoce (Fortunien précoce) du Groupe de Belleisle Bay. En raison en partie de cette relation, on estimait que le groupe d'Almond Road datait du Cambrien précoce, quoique la limite d'âge supérieure n'ait pas été déterminée. Une datation U-Pb (zircon) de 475 [+ or -] 2 Ma pour le porphyre de West Scotch Settlement, une petite intrusion felsique hypabyssale à position fixe de la formation de Ketchum Brook, montre que le groupe d'Almond Road ne date pas d'avant l'Ordovicien précoce (Floien précoce). Les données tirées du zircon détritique d'un échantillon de quartzite basal de la formation de Snider Mountain par spectromètre de masse à plasma inductif à ablation par laser restreignent l'âge davantage. Les résultats indiquent un sommet dominant pendant l'Édiacarien (environ 575 Ma), la plus jeune grappe d'âges cohérente étant d'environ 530 à 520 Ma. Mises ensemble, ces données appuient l'âge du Cambrien pour le groupe d'Almond Road riche en quartz, de même que sa relation avec les plates-formes du Gandérien. [Traduit par la redaction], INTRODUCTION AND REGIONAL GEOLOGICAL SETTING The New River belt (NRB) is the westernmost of three Proterozoic lithotectonic belts within the broader northeastern Appalachian orogen in southern New Brunswick (Fig. 1). [...]

The Partridge Island block is a newly identified tectonic element in the Saint John area of southern New Brunswick, located south of and in faulted contact with Proterozoic and Cambrian rocks of the Ganderian Brookville and Avalonian Caledonia terranes. It includes the Lorneville Group and Tiner Point complex. The Lorneville Group consists of interbedded volcanic and sedimentary rocks, subdivided into the Taylors Island Formation west of Saint John Harbour and West Beach Formation east of Saint John Harbour. A sample from thin rhyolite layers interbedded with basaltic flows of the Taylors Island Formation at Sheldon Point yielded a Late Devonian - Early Carboniferous U-Pb (zircon) age of 358.9 +6/-5 Ma. Petrological similarities indicate that all of the basaltic rocks of the Taylors Island and West Beach formations are of similar age and formed in a continental within-plate tectonic setting. West of Saint John Harbour, basaltic and sedimentary rocks of the Taylors Island Formation are increasingly deformed and mylonitic to the south, and in part tectonically interlayered with mylonitic granitoid rocks and minor metasedimentary rocks of the Tiner Point complex. Based on magnetic signatures, the deformed rocks of the Tiner Point complex can be traced through Partridge Island to the eastern side of Saint John Harbour, where together with the West Beach Formation, they occupy a thrust sheet above a redbed sequence of the mid-Carboniferous Balls Lake Formation. The Tiner Point complex includes leucotonalite and aegirine-bearing alkali-feldspar granite with A-type chemical affinity and Early Carboniferous U-Pb (zircon) ages of 353.6 ± 5.7 and 346.4 [+ or -] 0.7 Ma, respectively. Based on similarities in age, petrological characteristics, alteration, iron oxide--copper-gold (IOCG)-type mineralization, and deformation style, the Partridge Island block is correlated with Late Devonian--Early Carboniferous volcanic- sedimentaryplutonic rocks of the Cobequid Highlands in northern mainland Nova Scotia. Deformation was likely a result of dextral transpression along the Cobequid-Chedabucto fault zone during juxtaposition of the Meguma terrane. Le bloc de Partridge Island est un element tectonique nouvellement identifie dans la region de Saint John du sud du Nouveau-Brunswick; il est situe au sud et dans un contact de faille avec des roches datant du Proterozoique et du Cambrien des terranes de Brookville (Ganderien) et de Caldonia (Avalonien). Le bloc comprend le Groupe de Lorneville et le complexe de Tiner Point. Le Groupe de Lorneville est forme de roches volcaniques et sedimentaires interlitees, subdivisees entre la Formation de Taylors Island a l'ouest du port de Saint John et la Formation de West Beach a l'est. Un echantillon de minces couches de rhyolite interlitees avec des ecoulements basaltiques de la Formation de Taylors Island a la pointe Sheldon a donne un age Devonien tardif - Carbonifere precoce de 358,9 +6/-5 Ma, determine par U-Pb sur zircon. Des similitudes petrologiques indiquent que toutes les roches basaltiques des formations de Taylors Island et de West Beach ont un age similaire et qu'elles ont ete formees dans un environnement continental a l'interieur d'une plaque tectonique. A l'ouest du port de Saint John, des roches basaltiques et sedimentaires de la Formation de Taylors Island sont de plus en plus deformees et mylonitiques vers le sud; elles sont aussi en partie interlitees tectoniquement avec des roches granitoides mylonitiques et des roches metasedimentaires accessoires du complexe de Tiner Point. En se basant sur les signatures magnetiques, les roches deformees du complexe de Tiner Point peuvent etre retracees a travers l'lle Partridge, jusqu'au cote est du port de Saint John ou, avec la Formation de West Beach, elles forment une nappe de charriage au-dessus d'une sequence de lits rouges de la Formation de Balls Lake (Carbonifere moyen). Le complexe de Tiner Point comprend des granites alcalins feldspathiques avec une tonalite leucocrate et de l'aegyrine qui ont une affinite chimique de type A; ils datent du Carbonifere precoce et ont des ages respectifs de 353,6 ± 5,7 et 346,4 ± 0,7 Ma determines par datation U-Pb sur zircons. En se basant sur les similitudes d'age, les caracteristiques petrologiques, l'alteration, la mineralisation de type IOCG (oxyde de fer, cuivre, or) et le style de deformation, le bloc de Partridge Island est correle avec les roches volcaniques sedimentaires plutoniques (Devonien tardif - Carbonifere precoce) des hautes terres de Cobequid dans le nord de la partie continentale de la Nouvelle-Ecosse. La deformation proviendrait d'une transpression dextre le long de la zone de failles Cobequid-Chedabucto durant la juxtaposition du terrane de Meguma. [Traduit par la Redaction], Introduction Southern New Brunswick consists of a collage of inferred peri-Gondwanan terranes and terrane fragments (Fig. 1), some of which may have been part of the microcontinent of Ganderia and [...]

ABSTRACT The islands known as The Wolves are located in the Bay of Fundy, approximately 10 km offshore from mainland southwestern New Brunswick. They are underlain by monzodiorite, gradational to [...]

New structural, geochronological, and geochemical data from the Acatlan Complex of southern Mexico show that it preserves a complete history of Pangea, from assembly to breakup. Previously interpreted to be a vestige of the Iapetus suture, the Acatlan Complex records a history that can be sequentially linked to the Rheic Ocean, the paleo-Pacific, and the Gulf of Mexico. This record is interpreted to reflect: (1) the development of a rift-passive margin on the southern flank of the Rheic Ocean in the Cambrian--Ordovician; (2) the formation of an extensional regime along the formerly active northern margin of Gondwana throughout the Ordovician; (3) closure of the Rheic Ocean documented by subduction-related eclogite facies metamorphism and exhumation during the Late Devonian-Mississippian; (4) Permian-Triassic convergent tectonics on the paleo-Pacific margin of Pangea; and (5) interaction with a Jurassic mantle plume coeval with the opening of the Gulf of Mexico. Keywords: Acatlan Complex, Pangea, Mexico, Rheic Ocean, paleo-Pacific, Gulf of Mexico.

Recent data indicating that the Piaxtla Suite (Acatlan Complex, southern Mexico) underwent eclogite-facies metamorphism and exhumation during the Devono-Carboniferous suggest an origin within the Rheic Ocean rather than the Iapetus Ocean. The Asis Lithodeme (Piaxtla Suite) consists of polydeformed metasediments and eclogitic amphibolites that are intruded by megacrystic granitoid rocks. U--Pb (zircon) data indicate that the metasediments were deposited after c. 700 Ma and before intrusion of c. 470-420 Ma quartz-augen granite. The metasedimentary rocks contain abundant Mesoproterozoic detrital zircons (c. 1050-1250 Ma) and a few zircons in the range of c. 900-992 and c. 1330-1662 Ma. Their geochemical and Sm-Nd isotopic signature is typical of rift-related, passive margin sediments derived from an ancient cratonic source, which is interpreted to be the adjacent Mesoproterozoic Oaxacan Complex. Megacrystic granites were derived by partial melting of a c. 1 Ga crustal source, similar to the Oaxacan Complex. Amphibolitic layers exhibit a continental tholeiitic geochemistry, with a c. 0.8-1.1 Ga source (ToM age), and are inferred to have originated in a rift-related environment by melting of lithospheric mantle in the Ordovician. This rifting may be related to the Early Ordovician drift of peri-Gondwanan terranes (e.g. Avalonia) from Gondwana and the origin of the Rheic Ocean.

The Eastern Blue Ridge Province of the southern Appalachians contains, in part, remnants of an Ordovician accretionary wedge complex formed during subduction of an oceanic tract before mid-Ordovician accretion with Laurentia. The Eastern Blue Ridge Province consists of metapelite and amphibolite intruded by low-K plutons, high-temperature (T >750 [degrees]C) Ordovician eclogite, and other high-pressure metamafic and meta-ultramafic rocks. Felsic plutons in the Eastern Blue Ridge Province are important time markers for regional-scale tectonics, deformation, and metamorphism. Plutons were thought to be related to either Taconian (Ordovician) or Acadian (Devonian-Silurian) tectonothermal events. We dated five plutonic or metaplutonic rocks to constrain pluton crystallization ages better and thus the timing of tectonism. The Persimmon Creek gneiss yielded a protolith crystallization age of 455.7 [+ or -] 2.1 Ma, Chalk Mountain 377.7 [+ or -] 2.5 Ma, Mt. Airy 334 [+ or -] 3 Ma, Stone Mountain 335.6 [+ or -] 1.0 Ma, and Rabun 335.1 [+ or -] 2.8 Ma. The latter four plutons were thought to be part of the Acadian 'Spruce Pine Suite,' but instead our new ages indicate that Alleghanian (Carboniferous-Permian) plutonism is widespread and voluminous in the Eastern Blue Ridge Province. The Chattahoochee fault, which was considered an Acadian structure, cuts the Rabun pluton and thus must have been active during the Alleghanian orogeny. The new ages indicate that Persimmon Creek crystallized less than 3 m.y. after zircon crystallization in Eastern Blue Ridge eclogite and is nearly synchronous with nearby high-grade metamorphism and migmatization. The three phases of plutonism in the Eastern Blue Ridge Province correspond with established metamorphic ages for each of the three major orogenic pulses along the western flank of the southern Appalachians. Keywords: U-Pb, geochronology, zircon, monazite, Southern Appalachians, plutons.

Detrital zircons from three Neoproterozoic sandstone units from the Cadomia terrane of northern France and the Channel Islands yield ages in three broad groups: late Neoproterozoic (650-600 Ma), early Palaeoproterozoic (2.4-2.0 Ga) and Archaean (>2.5 Ga). The hack of Mesoproterozoic zircon crystals, combined with the high abundance of grains between 2.20 and 2.00 Ga, corresponds closely to the ages of exposed rocks in the West Africa Craton, and thus it is suggested that Cadornia was in close proximity to West Africa by c. 580 Ma. In contrast, the main age groups of detrital zircon from the Neoproterozoic Avalon terrane are Mesoproterozoic and there is a distinct gap of ages between 2.40 and 2.05 Ga. These significant differences suggest that the two terranes were in different locations relative to major Gondwanan cratons in latest Neoproterozoic time. Keywords: Cadomian Orogeny, U-Pb, detrital zircon, palaeogeography.

There has been a conspicuous absence of documented Acadian structures in the Blue Ridge province of the southern Appalachians even though a growing body of evidence suggests that the middle Paleozoic Acadian orogeny affected the rocks of this region. New mapping along with structural, petrologic, and geochronologic data from western North Carolina show that the contact between the metasedimentary and metavolcanic rocks of the Ashe Metamorphic Suite and the Grenville basement rocks of the western Blue Ridge corresponds to a Devonian high-grade, dextral strike-slip fault zone, the Burnsville fault. Timing of motion on the Burnsville fault is constrained by field relationships, metamorphic fabrics and assemblages, and radiometric ages. A U-Pb zircon crystallization age for a pegmatite sheared by the Burnsville fault shows that the last movement on the fault must be younger than 377 Ma. Previously published [sup.40]Ar/[sup.39]Ar cooling ages show that the Burnsville fault must be older than ca. 360 Ma. We have mapped the Burnsville fault for ~100 km in northwestern North Carolina. The Gossan Lead fault of northwesternmost North Carolina and southwestern Virginia is the likely continuation of the Burnsville fault to the northeast. Southwest of Asheville, North Carolina, the Burnsville fault may connect to the Devonian Dahlonega shear zone, or may be cut by post-Devonian thrust faults associated with the Alleghanian orogeny. Diachroneity of Acadian clastic wedges, the presence of Silurian-Devonian pull-apart basins, the presence of Devonian high-grade, dextral shearing in the Inner Piedmont, and recent plate reconstructions for the middle Paleozoic, support the interpretation that the late phase of the Acadian orogeny in the southern Appalachians was primarily a dextral transpressional event. The Burnsville fault and the Inner Piedmont formed the boundaries of a dextral transform margin that may have extended the length of the Appalachian orogen. This interpretation requires that models for the Paleozoic tectonics of the Appalachians incorporate major pre-Alleghanian dextral displacement. Keywords: Structural geology, tectonics, Appalachians, Acadian orogeny, Burnsville fault, strike-slip faults.

ABSTRACT Late Proterozoic to Early Cambrian igneous rocks are major components of the fault-bounded Caledonia, Brookville, and New River terranes of southern New Brunswick. As previously demonstrated, ca. 620 Ma [...]

The fault-bounded Kingston terrane of southern New Brunswick consists of felsic and less abundant mafic volcaniclastic rocks and flows and minor interbedded sedimentary rocks of the Kingston Group intruded by mainly granitic plutons and abundant younger mafic sheets. The granitic plutons form about half of the terrane and are characterized by fine grain size and typically granophyric and porphyritic textures, indicative of high-level emplacement. Mafic sheets were emplaced in the granitic plutons and parallel to primary layering in the Kingston Group, which is typically steeply dipping and trends northeast to north-northeast. Hence, in contrast to some earlier interpretations, the Kingston terrane does not consist of a bimodai dike complex. The Kingston Group, granitic rocks, and mafic sheets contain mineral assemblages consistent with metamorphism to upper greenschist-lower amphibolite facies. New U-Pb (zircon) ages of 442 [+ or -] 6 Ma from a dacitic tuff unit and 437 [+ or -] 10 Ma from a granitic pluton corroborate previous U-Pb dates that had suggested that the volcanic and granitic rocks in the Kingston terrane are Early Silurian, rather than Precambrian, as had been earlier assumed. The felsic volcanic and granitic rocks are interpreted to be comagmatic on the basis of their field relationships and similar U-Pb ages and chemical character. Compositions of both the felsic rocks and less abundant mafic and intermediate and mafic rocks are consistent with calc-alkalic affinity and emplacement in a continental-margin volcanic arc, herein termed the Kingston arc. A U-Pb date of 435 [+ or -] 5 Ma was also obtained from compositionally similar granite that forms a dike in an adjacent fault-bounded amphibolite-facies metasedimentary unit. The similarity in age and composition of the granite dike suggests a link between these metasedimentary rocks and the Kingston terrane, possibly as part of an accretionary complex. If so, its location southeast of the Kingston terrane indicates that subduction was to the present northwest. Mafic sheets in the Kingston terrane are tholeiitic but have some arc-like characteristics, consistent with their origin in a former arc setting, but the sheets were likely emplaced in a subsequent extensional setting. The compositional similarity of the mafic sheets to Late Silurian mafic volcanic rocks and plutons of the Coastal Maine magmatic province suggests that they may be related. A possible model for evolution of the Kingston terrane is proposed, wherein the Kingston Group and related granite formed in an Early Silurian arc on the margin of Ganderia, as represented by the New River terrane of late Precambrian and early Paleozoic age. Northwestward subduction culminated in collision between the Kingston arc and a continental block now represented by the Brookville terrane to the southeast. Subsequent transpressive motions in the Late Silurian may have been responsible for the crustalscale extensional environment in which the Coastal Maine magmatic province was formed, including emplacement of mafic dikes into the deformed former Kingston arc. Transpressive motions-related to juxtaposition of the Avalon and Meguma terranes with the previously accreted, more inboard terranes--continued through the Devonian and into the Carboniferous. Keywords: Appalachians, geochemistry, Silurian, U-Pb dating, volcanic arcs.

ABSTRACT Latest Neoproterozoic and Cambrian plutons in the Brookville terrane of southern New Brunswick are termed the Golden Grove Plutonic Suite. Four groups are recognized on the basis of composition: [...]

The intrusive suite of Yosemite Valley provides an excellent example of coeval mafic and felsic magmatism in a continental-margin arc. Within the suite, hornblende gabbros and diorites associated with the Cretaceous El Capitan and Taft Granites occur as scattered mafic enclaves, enclave swarms, small pods, synplutonic dikes, and a 2 [km.sup.2] mafic complex known as the 'diorite of the Rockslides.' Field evidence suggests that most of the mafic rocks are temporally related to the El Capitan Granite and that significantly less mafic magma accompanied the slightly later intrusion of the Taft Granite. Concordant zircon fractions from the diorite of the Rockslides yield an age of 103 [+ or -] 0.15 Ma, which is the same age as the El Capitan Granite. Initial isotopic compositions of the mafic and felsic rocks are similar; the mafic rocks exhibit only slightly higher [sup.87]Sr/[sup.86]Sr, lower [sup.143]Nd/ [sup.144]Nd, and higher [sup.206]Pb/[sup.204]Pb ratios than the granites. Because the mafic magmas are only slightly more isotopically evolved than the granites, geochemical variation within the granites is not easily explained in terms of contamination of a depleted-mantle component by partial melts of ancient, high-silica continental crust. Rather, these data are consistent with an interpretation that the El Capitan Granite was derived by partial melting of relatively young mafic sources broadly similar to the mafic rocks of the suite. Keywords: granite, isotopes, mafic magmas, Sierra Nevada batholith, Yosemite National Park.

Uranium-lead dates for single and small multiple grain zircon separates are presented for the main geological units from Jersey, British Channel Islands. A turbiditic sandstone from the Jersey Shale Formation (Brioverian Supergroup) contains detrital zircons of a variety of ages, ranging from c. 2.6 to 0.6 Ga. The youngest zircons yielded nearly concordant U-Pb dates of 586.7 [+ or -] 3.0 Ma and 587.1 [+ or -] 2.7 Ma providing a maximum depositional age for the unit. Zircons from overlying volcanic rocks (Anne Port Rhyolite) give an upper intercept date of [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII] Ma, considered to be the age of eruption. The undeformed SW Jersey granite, which intrudes and locally thermally metamorphoses the folded Jersey Shale Formation, is dated at [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII] Ma. These dates constrain tightly the timing of deposition of the Jersey Shale Formation and the age of deformation on Jersey, and indicate a dynamic arc environment during the late Neoproterozoic. Zircons from the NW Jersey granite define an upper intercept date of 482.7 [+ or -] 1.6 Ma, similar to the previously reported [sup.40]Ar/[sup.39]Ar hornblende date of c. 473 Ma, confirming a renewed pulse of magmatism during the Ordovician in this sector of Cadomia. Keywords: Cadomian Orogeny, U-Pb, absolute age, Channel Islands, Jersey.