The British–Irish Palaeogene Igneous Province (BIPIP) is part of the larger North Atlantic Igneous Province and includes the lava fields of Antrim, Mull, and Skye. The Tardree Rhyolite Complex (TRC) in Northern Ireland forms an important stratigraphic unit between the Lower and Upper Basalt Formations of the Antrim Lava Group (ALG). Previous zircon age determinations obtained from the TRC have been used as a standard in zircon fission track studies, but contradict several 40Ar/39Ar sanidine and U–Pb zircon results. We provide new 40Ar/39Ar sanidine and U–Pb CA-TIMS zircon ages which resolve this discrepancy. Two sanidine samples from the Sandy Braes vent and the columnar-jointed dome-forming rhyolites of Tardree Forest yield a weighted mean 40Ar/39Ar age of 61.13±0.42Ma (2σ, internal error). Ten U–Pb CA-TIMS zircon analyses were undertaken, eight of which employed the CA-TIMS approach on both multi-grain fractions and single grains. Six of the CA-TIMS data yield a disequilibrium-corrected weighted mean 206Pb–238U age of 61.32±0.09Ma (2σ). The consistency of the 40Ar/39Ar ages with the CA-TIMS U–Pb zircon age, points to a closed system of both K and Ar since eruption. We propose that the crystallization age of the TRC be taken as 61.32±0.09Ma and that the currently used age of the zircon fission track standard (58.4±0.7Ma) be changed accordingly. This also places the eruption of the TRC in magnetochron C26r, which is consistent with the reversed polarity magnetic remanence observed in the ALG, and supports the conclusion of Ganerød et al. (2010) that the Lower Basalt Formation is older than the Vaigat Formation in Western Greenland. No resolvable zircon inheritance has been detected by the TIMS analyses, consistent with the fact that the temporal and geographic extent of rhyolitic magmatism within this sector of the BIPIP was very limited, and hence was unlikely to provide inherited magmatic zircons from slightly older magmas (antecrysts). Potentially older zircon xenocrysts would be derived from the underlying Caledonian basement (>400Ma) or yet older rocks. These should be easily detectable if the Tardree zircon was to be employed as a U–Pb zircon standard. The paired 40Ar/39Ar and 206Pb–238U results from this study indicate an age of 28.393±0.194Ma for the widely used Fish Canyon sanidine standard and gives further support to the recent calibrations of Kuiper et al. (2008) and Renne et al. (2010).

Large igneous provinces (LIPs) have recently been suggested to originate at the edges of low-velocity zones on the core mantle boundary (Plume Generation Zones). If true, LIPs can potentially be used to constrain paleolongitude in plate tectonic reconstructions. To validate the hypothesis, it is essential to study LIPs of which the paleolongitude can be constrained by other methods, such as hotspot reference frames. An ideal candidate to this end is the early Cenozoic North Atlantic Igneous Province (NAIP). Despite being the largest volcanic unit of the British Tertiary Igneous Province (BTIP, part of the NAIP), the age and paleoposition of the Antrim Lava Group (ALG) in Northern Ireland, which is key to the NAIP as a whole, was hitherto poorly constrained. In this paper, we therefore present an integrated high-resolution paleomagnetic and geochronological study. The ALG is divided into three formations: the Lower Basalt Formation (LBF), Interbasaltic Formation (IBF) and the Upper Basalt Formation (UBF). The IBF is mostly lateritic and encloses the Tardree rhyolite. We offer new age constraints from all three formations using the 40Ar/39Ar method and propose that 62.6 ± 0.3, 61.3 ± 0.3 and 59.6 ± 0.3 Ma (1σ, internal uncertainties) are sound estimates of the age of emplacement of the LBF, Tardree rhyolite (IBF) and UBF, respectively. This constrains the nominal duration of emplacement of the ALG to 3 ± 0.6 Ma (1σ). This reevaluation of the magnetic signature in the ALG revealed reverse polarity remanence in all three formations and an overall paleomagnetic north pole at latitude 78.9°N, longitude 167°E (A95 = 6.3; age ∼61 Ma) in the European reference system. This appears consistent with paleomagnetic poles from the rest of the NAIP; both in Europe and Greenland, as well as predictions from modern apparent polar wander paths. The new radiometric ages span magnetochron C26r, C27n and C27r. The normal polarity chron C27n most probably occurred during the IBF hiatus, explaining why no normal polarity remanence was detected in the paleomagnetic investigation. Emplacement of the LBF falls in magnetochron C27r, making this one of the oldest lava sequence in the NAIP; older than the C27n lava pile in Western Greenland. The 60 Ma position of the NAIP in a paleomagnetic reference frame, puts it close to the northern edge of the African large low shear wave velocity anomaly at the core–mantle boundary and therefore in the line with the Plume Generation Zone hypothesis. However, the back-projected Icelandic hotspot, normally considered to have formed the NAIP, is located ∼1500 km north of the latitude at which the NAIP erupted. The northward motion of the north Atlantic lithosphere since the late Cretaceous challenging the existing correlation of the NAIP to the Icelandic hotspot, normally used to explain the observed pre- and syn-breakup North Atlantic magmatism (63–55 Ma), and either an additional plume located further south in the North Atlantic may be invoked to create the NAIP, or the Icelandic hotspot must have undergone a northward motion together with the North Atlantic lithosphere (which according to present mantle flow models seems unlikely).

This paper presents results of a large multidiciplinary geological mapping project in NE Mozambique, with a focus on the structural evolution of this part of the East African Orogen (EAO). It integrates field structural studies with geophysical interpretations and presents new geochronological data. The tectonic architecture of NE Mozambique can be subdivided into five megatectonic units on the basis of lithology, structure and geochronology: unit 1, Paleoproterozoic Ponta Messuli Complex in the extreme NW corner of NE Mozambique, which represents the local NW foreland to the EAO; unit 2, a collage of Mesoproterozoic metamorphic complexes, which forms the basement to unit 3, a stack of Neoproterozoic, NW directed imbricate thrust nappes named here the “Cabo Delgado Nappe Complex” (CDNC); unit 4, restricted Neoproterozoic metasedimentary basins; and unit 5, two exotic Neoproterozoic granulite mélange complexes. The units were assembled during a long and complex history of NW directed shortening, which commenced with nappe stacking and emplacement of the CDNC over the Mesoproterozoic basement terranes toward the NW foreland. It is proposed that the CDNC and the Eastern Granulites farther north in Tanzania are remnants of Neoproterozoic volcanic arcs and microcontinents formed “outboard” of the Mesoproterozoic continent after 596 ± 11 Ma. Field and potential field geophysical data show that the nappes were folded by regional‐scale NE–SW trending folds that formed in response to a later stage of the same shortening episode and this episode gave rise to the Lurio Belt, a prominent structural feature of northern Mozambique and a key element (often as suture zone) in many Gondwana reconstructions. The Lurio Belt is here interpreted as a structure generated during folding of the CDNC during later stages of the progressive shortening event. It is, however, a repeatedly reactivated shear zone, probably at the site of an older (Mesoproterozoic?) discontinuity, with an intense pure shear deformation history. It is cored by strongly attenuated lenses of a granulitic tectonic mélange, the Ocua Complex (megatectonic unit 5) and is intruded by Late Pan‐African granitoids of the Malema Suite. The compressional phase of the orogen was postdated by NW–SE directed extension. New U‐Pb zircon and monazite dates show that extension was initiated at circa 540 Ma in the eastern Lurio Belt. It is argued that extension was the result of a major episode of orogenic collapse of the EAO, initiated by gravitational instabilities resulting from crustal thickening during the shortening phase.

A detailed palaeomagnetic investigation of early Silurian volcanics of the Lawrenceton Formation in the Central Mobile Belt (CMB) of Newfoundland reveals primary remanence that places the sampled part of the CMB on the margin of Laurentia in low southerly latitudes in the early Silurian. The palaeomagnetic data indicate large vertical axis (net clockwise) rotations within the CMB and between the CMB and cratonic Laurentia. The volcanics were folded, faulted and in places cleaved in Silurian to Early Devonian times. Anisotropy of magnetic susceptibility measurements on lava flow samples verify field observations of a primary flow-parallel foliation and confirm field measurements of the palaeo-horizontal. A well-developed tectonic fabric was detected at one sampling site near the Reach Fault.Silurian redbeds of the Big Indian Pond Formation were also sampled for palaeomagnetic study. The sediments are folded, faulted and cleaved. A statistically sound syn-folding remanence was identified which, in a tectonically corrected state, is consistent in direction with the remanence in the Silurian volcanics. The sampled sediments are more intensely deformed than the volcanics and magnetic anisotropy measurements indicate both primary layering- and secondary cleavage-related fabrics in varying degrees from site to site. It is possible that cleavage development resulted in remanence reorientation leading to the illusion of syn-folding remanence when, in fact, the remanence was acquired prior to folding.Previously published palaeomagnetic investigations of Silurian rocks in the CMB revealed a discrepancy in palaeofield inclination between volcanic and sedimentary rock types. The sedimentary rocks yielded shallow inclinations and the volcanics intermediate inclinations. Inclination shallowing in the sediments was put forward as an explanation, as well as contamination of the sedimentary results with-a shallow overprint. Others argued that the results from the volcanics were in error. The present investigation demonstrates that key volcanics carry a shallower remanence than previously thought, bringing them into approximate agreement with the majority of the results from sediments. Steep results from the Springdale volcanics and very shallow results from the King George IV lake sediments are at variance with the rest of the data. The Springdale result has large error limits that overlap with the other data. The anomalous King George IV result remains an outlier. (C) 2002 Elsevier Science B.V. All rights reserved.

The Global Paleomagnetic Database (GPMDB) is a data base for paleomagnetic directions and pole positions. It was first compiled by Lock and McElhinny [1991] and made use of the PC version of the Oracle Database Management System, which at the time was the only PC system available that used SQL, the internationally recognized language for use with database management systems. Subsequently, the Oracle PC system became far too large and complex for the GPMDB, so the data base was transferred to Microsoft Access, which had just become available and also used SQL [McElhinny and Lock, 1996].

Aeromagnetic and marine gravity data sets for the northern North Sea and western Norway have been interpreted in terms of land to offshore tectonic links. The data allow identification of linking-structures both in crystalline basement and overlying sedimentary rocks and consequently facilitate a more comprehensive interpretation of regional structural features and trends. With the help of bathymetric data in the inshore region, major fault structures can be traced between western Norway and the offshore region west of the Øygarden Fault Zone. In this way spatial and chronological links have been established between tectonic events recognized on land and the development of the North Sea Basin. An interpretation of basement geology is proposed for the region between western Norway and the Uer Terrace. This is complemented with a depth to top crystalline basement map covering the North Sea Basin between the Uer terrace and the East Shetland Basin. Two regional NW–SE lineaments were recognized offshore western Norway and given the names Marflo Lineament and Troll Lineament. The Marflo Lineament is interpreted to be a Caledonian or older zone of weakness that accommodated development of a 20–30 km offset in the Jurassic Viking Graben axis. The lineament can be traced into the North Atlantic where it parallels oceanic fracture zones and transform faults. The Troll Lineament relates to a deep geological discontinuity crossing the Uer and Lomre Terraces. A grouping of earthquake epicentres along part of the lineament suggests that the discontinuity is tectonically active.

The Skagerrak and Silkeborg gravity and magnetic anomalies are situated in the Farsund Basin just offshore the southern tip of Norway and in central Jutland, Denmark, respectively. Gravity highs partly coincide with magnetic lows.

A combined interpretation of new high sensitivity aeromagnetic data (NAS-94), existing offshore and onland gravity and new petrophysical data between 64°30' and 68°N in the Norwegian Sea offshore Norway was carried out on behalf of Amoco, Mobil Exploration, Norsk Hydro , Statoil and the Geological Survey of Norway (Olesen & Smethurst 1995).

Data from over 20 years of diverse aeromagnetic surveys in Norway have been compiled into a single grid by the Geological Survey of Norway (NGU). Taken together, the surveys comprise 500000 line-krn, covering approximately 400000 krrr', 324000 km2 of which are over land. The compilation is the first to offer a comprehensive picture of magnetic anomalies over mainland Norway.

There is a discrepancy between Ordovician palaeomagnetic pole positions from the Russian Plate and from Scandinavia; however, it is clear from faunal and tectonic evidence that the two regions were parts of a single continent through Palaeozoic time. Data from both regions are few in number and some are controversial in nature. Therefore it is suggested that the palaeomagnetic discrepancy merely reflects the incomplete nature of the palaeomagnetic dataset for Baltica.It is notable that palaeolatitudes for Baltica derived from the Scandinavian dataset are confirmed by other lines of geological evidence. It is therefore concluded that the Scandinavian dataset offers the most reliable palaeomagnetic controls on the Lower Palaeozoic drift history of Baltica, placing it in mid-southerly latitudes in Early Ordovician time, rotated clockwise through at least 50-degrees relative to its present orientation.

Palaeozoic palaeomagnetic data from Scotland and Ireland have been compared on a terrane model, and early Caledonide clockwise rotation of a terrane through 65º ± 30° (Connemara Massif) and later anticlockwise rotation of up to 50° (in the vicinity of Clew Bay) have been deduced. These are the firfirst estimates of terrane rotations in the European part of the Caledonian–Appalachian orogen. Terrane analysis of orogenic belts is currently a major field of study. To a large extent this has been stimulated by studies in the North American Cordillera where large rotations and translations have been determined palaeomagnetically (see Beck et al. 1986 and references therein). Terrane analysis may be applied to older orogenic belts such as the Caledonides, which have been particularly intensively studied. Previously published palaeomagnetic data from Connemara (Morris & Tanner 1977) and NW Galway ( Morris et al. 1973 ) had indicated local block rotations, but furnished few constraints on either their age and magnitude, or on the identities of the blocks. This paper relates the currently available palaeomagnetic dataseto a terrane model of W. Ireland (Hutton & Dewey 1986), see Fig. 1. New data. New palaeomagnetic data from the Irish Caledonides comprise the following. Connemara Gabbro ( Robertson 1988 ). The Dalradian rocks of the Connemara Massif are unique in the British Caledonides in lying to the south of a Caledonian ophiolite and also south of a thick sequence of Ordovician shales and volcanics of low metamorphic grade (in Clew Bay and the South Mayo Trough respectively). The structural