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The Puduhush gabbro is located on the western margin of the proto-Kalahari Craton in Southern Africa. This gabbro intrudes the Volop Formation, which conformably overlies the Hartley Formation lava of the late Palaeoproterozoic Olifantshoek Group. Here we report a new U-Pb ID-TIMS baddeleyite age as well as petrographic, whole-rock geochemical and palaeomagnetic results for the Puduhush gabbro. The gabbro shows a well-preserved sub-ophitic texture between clinopyroxene and plagioclase, with minor amounts of amphibole, olivine, biotite and Fe-Ti oxides. The new U-Pb ID-TIMS baddeleyite age of 1 881 ± 1 Ma reported here for the Puduhush gabbro, together with existing ages for the Hartley Formation, define a ca.1 916 to 1 881 Ma age bracket for the Volop Formation. Our 1 881 ± 1 Ma age is also within error of ages reported for the oldest episode (so-called Episode 1) of the ca.1.89 to 1.83 Ga magmatism in the eastern and northern parts of the proto-Kalahari Craton. Our geochemical results also suggest compositional similarities between the Puduhush gabbro and Episode 1 magmatism, particularly the post-Waterberg sills. The virtual geomagnetic pole calculated here for the Puduhush gabbro (VGP: 1.6°N; 352.0°E; A95 = 14.2°) is consistent with the Episode 1 pole. All data are therefore combined to produce a new palaeomagnetic pole (11.7°N; 8.8°E, A95 = 9.3°) for Episode 1 magmatism. The present study provides the first evidence that the ca.1.89 to 1.83 Ga magmatism had a wider footprint that previously thought, extending to the western margin of the proto-Kalahari Craton. This wide-scale magmatism, previously proposed to be related to a back-arc extension setting, is here reinterpreted in the context of a mantle plume. Our results are consistent with the lithostratigraphic-based notion that at least parts of the red-bed successions (i.e., Olifantshoek and Waterberg Groups) that are hosts to the ca.1.89 to 1.83 Ga magmatism could be correlative units, representing an extensive sedimentary sequence that once covered large expanses of the proto-Kalahari Craton.

The Rodinia supercontinent broke apart during the Neoproterozoic. Rodinia break-up is associated with widespread intraplate magmatism on many cratons, including the c. 720–719 Ma Franklin large igneous province (LIP) of Laurentia. Coeval magmatism has also been identified recently in Siberia and South China. This extensive magmatism terminates ∼1 myr before the onset of the Sturtian Snowball Earth. However, LIP-scale magmatism and global glaciation are probably related. U–Pb isotope dilution–thermal ionization mass spectrometry (ID-TIMS) baddeleyite dating herein identifies remnants of a new c. 724–712 Ma LIP on the eastern Kalahari Craton in southern Africa and East Antarctica: the combined Mutare–Fingeren Dyke Swarm. This dyke swarm occurs in northeastern Zimbabwe (Mutare Dyke Swarm) and western Dronning Maud Land (Fingeren Dyke Swarm). It has incompatible element-enriched mid-ocean ridge basalt-like geochemistry, suggesting an asthenospheric mantle source for the LIP. The Mutare–Fingeren LIP probably formed during rifting. This rifting would have occurred almost ∼100 myr earlier than previous estimates in eastern Kalahari. The placement of Kalahari against southeastern Laurentia in Rodinia is also questioned. Proposed alternatives, invoking linking terranes between Kalahari and southwestern Laurentia or close to northwestern Laurentia, also present challenges with no discernible resolution. Nevertheless, LIP-scale magmatism being responsible for the Sturtian Snowball Earth significantly increases.

The Precambrian comprises the vast majority of Earth’s history. Preserved archives contain essential information about the first few billion years for planetary evolution of our planet. Despite covering a large part of the history of our planet, these outcrops are not so abundant due to erosion and frequently occur in disparate areas. In order to relate them and to establish a timeline of geological events in a world lacking biochronology, we rely on accurate radio-isotopic age determinations. These are, however, rather scarce and still leave several hundreds of million years long time intervals undated. In this study, we present U-Pb age determinations from volcanic and sedimentary units of the Paleoproterozoic Transvaal Supergroup, South Africa. The Transvaal Supergroup is an exceptionally well preserved sequence and therefore accounts for a very large amount of geochemical data. Due to its capacity to produce large data sets the preferred technique in U-Pb zircon geochronology for ancient sediments is LA-ICP-MS. It allows the aqcuisition of maximum depositional ages (MDA) in a fast way and at a relatively low cost. However, the large analytical uncertainty preclude the temporal resolution to distinguish between different processes in such old rocks. Moreover, the standard dating procedure rarely includes zircon treatment via chemical abrasion to mitigate common problems such as open system behavior due to radioactive decay damage related Pb loss. In consequence, interpreted ages might be severely disturbed and may yield MDA’s that are tens to hundreds of million years too young. As an alternative, the much more work-intensive CA-ID-TIMS technique allows the obtention of more accurate and more precise ages, preferably using zircon grains that have previously been screened for their LA-ICP-MS U-Pb age. Our new combined LA-ICP-MS and CA-ID-TIMS data indicates that the glaciogenic Makganyene Formation has a MDA of ~2.42 Ga. Younger age clusters at around ~2.2 Ga from LA-ICP-MS dating disappear with chemical abrasion and have to be interpreted as artifacts of radiation-damage related Pb loss. These new results have important implications for both environmental evolution during the Neoarchean/Paleoproterozoic, as well as for the regional geology. The Makganyene diamictites are thought to represent the oldest Paleoproterozoic glaciation in South Africa. The data also corroborate the hypothesis that the directly overlying-to-locally-interfingered mafic volcanic Ongeluk Formation is ~200 Ma older than the volcanic rocks ~2250 Ma Hekpoort Formation in the East Transvaal basin. We therefore reject the long-standing correlation between both units, as previously published.We demonstrate that LA-ICP-MS is not capable to provide a robust and reliable MDA’s in ancient clastic sediments. CA-ID-TIMS analysis provides dates of significantly higher accuracy, because the chemical abrasion is minimizing Pb-loss in the crystal. Therefore, for studies relying on U-Pb zircon geochronology, we encourage the application of CA-ID-TIMS in the youngest populations previously identified with the LA-ICP-MS. This is particularly important for establishing reliable maximum depositional ages in sedimentary rocks.

Although Variscan terranes have been documented from the Balkans to the Caucasus, the southeastern portion of the Variscan Belt is not well understood. The Strandja Zone along the border between Bulgaria and Turkey encompasses one such terrane linking the Balkanides and the Pontides. However, the evolution of this terrane, and the Late Carboniferous to Triassic granitoids within it, is poorly resolved. Here we present laser ablation – inductively coupled plasma – mass spectrometry (LA-ICP-MS) U–Pb zircon ages, coupled with petrography and geochemistry from the Izvorovo Pluton within the Sakar Unit (Strandja Zone). This pluton is composed of variably metamorphosed and deformed granites which yield crystallization ages of c. 251–256 Ma. These ages are older than the previously assumed age of the Izvorovo Pluton based on a postulated genetic relationship between the Izvorovo Pluton and Late Jurassic to Early Cretaceous metamorphism. A better understanding of units across the Strandja Zone can now be achieved, revealing two age groups of plutons within it. An extensive magmatic episode occurred c. 312–295 Ma, and a longer-lived episode between c. 275 and 230 Ma. Intrusions associated with both magmatic events were emplaced into pre-Late Carboniferous basement, and were overprinted by Early Alpine metamorphism and deformation. These two stages of magmatism can likely be attributed to changes in tectonic setting in the Strandja Zone. Such a change in tectonic setting is likely related to the collision between Gondwana-derived terranes and Laurussia, followed by either subduction of the Palaeo-Tethys Ocean beneath Laurussia or rifting in the southern margin of Laurussia, with granitoids forming in different tectonic environments.

The 1.87–1.84 Ga Black Hills dike swarm of the Kalahari craton (South Africa) is coeval with several regional magmatic provinces used here to resolve the craton's position during Columbia assembly. We report a new 1850 ± 4 Ma (U-Pb isotope dilution–thermal ionization mass spectrometry [ID-TIMS] on baddeleyite) crystallization age for one dike and new paleomagnetic data for 34 dikes of which 8 have precise U-Pb ages. Results are constrained by positive baked-contact and reversal tests, which combined with existing data produce a 1.87–1.84 Ga mean pole from 63 individual dikes. By integrating paleomagnetic and geochronological data sets, we calculate poles for three magmatic episodes and produce a magnetostratigraphic record. At 1.88 Ga, the Kalahari craton is reconstructed next to the Superior craton so that their ca. 2.0 Ga poles align. As such, magmatism forms part of a radiating pattern with the coeval ca. 1.88 Ga Circum-Superior large igneous province.

The Singhbhum Craton in eastern India is host to at least seven sets of mafic dyke swarms. Four previously dated swarms (studied here) include the NNE-trending Keshargaria (ca. 2.80 Ga) and Ghatgaon (ca. 2.76 - 2.75 Ga) swarms, the ENE-trending Kaptipada swarm (ca. 2.26 Ga), and the ESE-trending Pipilia swarm (ca.1.76 Ga). The dykes range in composition from basalt to andesite and have transitional tholeiitic to calc-alkaline affinities. They show intra- and inter-swarm geochemical and Sr-Nd isotopic heterogeneities and have SiO2 content ranging from 47 to 60 wt.%. The chondrite normalized REE patterns show enrichment in LREE and the Primitive-Mantle normalized multi-element patterns show elevated U, Th, Cs, Rb, K, and Pb; and depletion in Nb, Ta, and Ti. These characteristics indicate involvement of crustal component in the petrogenesis of these dykes. The dykes of different swarms have variable 87Sr/86Sri and eNd(i) values, which define a crust-like isotopic growth trajectory with time from a common chondritic to depleted source that was enriched contemporaneously with the formation of the crustal rocks of the Singhbhum Craton. The isotope data indicate involvement of older enriched crustal material in the petrogenesis of these dykes. Variable but mostly high (compared to similarly evolved magmas) Ni (40 - 590 ppm), Cr (40 - 1110 ppm), and V (120 - 434 ppm) contents particularly of the most primitive dykes indicate that parental melts were in equilibrium with mantle peridotite and experienced only minor fractional crystallization of olivine, pyroxene, and magnetite. The Sr-Nd isotope ratios do not show any correlation with differentiation indices which indicates that the melts were not modified significantly by crustal assimilation during ascent and emplacement. The crust-like secular trend of the Sr and Nd isotopic compositions suggests that the enriched crustal material was incubated in the mantle (i.e., metasomatized lithospheric mantle) for a long time and this source was periodically tapped leading to multiple dyke emplacement events over at least 1 Gyr. The recycled crustal material played a role in metasomatizing the subcontinental lithospheric mantle prior to ca. 2.80 Ga. Mantle plume activity triggered melting of the metasomatized lithospheric mantle many times, leading to the emplacement of mafic dykes of different generations across the craton.

U-Pb geochronology on baddeleyite is a powerful technique that can be applied effectively to chronostratigraphy. In southern Africa, the Kaapvaal Craton hosts a well-preserved Mesoarchean to Paleoproterozoic geological record, including the Neoarchean Ventersdorp Supergroup. It overlies the Witwatersrand Supergroup and its world-class gold deposits. The Ventersdorp Supergroup comprises the Klipriviersberg Group, Platberg Group, and Pniel Group. However, the exact timing of formation of the Ventersdorp Supergroup is controversial. Here we present 2789 ± 4 Ma and 2787 ± 2 Ma U-Pb isotope dilution-thermal ionization mass spectrometry (ID-TIMS) baddeleyite ages and geochemistry on mafic sills intruding the Witwatersrand Supergroup, and we interpret these sills as feeders to the overlying Klipriviersberg Group flood basalts. This constrains the age of the Witwatersrand Supergroup and gold mineralization to at least ca. 2.79 Ga. We also report 2729 ± 5 Ma and 2724 ± 7 Ma U-Pb ID-TIMS baddeleyite ages and geochemistry from a mafic sill intruding the Pongola Supergroup and on an east-northeast–trending mafic dike, respectively. These new ages distinguish two of the Ventersdorp Supergroup magmatic events: the Klipriviersberg and Platberg. The Ventersdorp Supergroup can now be shown to initiate and terminate with two large igneous provinces (LIPs), the Klipriviersberg and Allanridge, which are separated by Platberg volcanism and sedimentation. The age of the Klipriviersberg LIP is 2791–2779 Ma, and Platberg volcanism occurred at 2754–2709 Ma. The Allanridge LIP occurred between 2709–2683 Ma. Klipriviersberg, Platberg, and Allanridge magmatism may be genetically related to mantle plume(s). Higher heat flow and crustal melting resulted as a mantle plume impinged below the Kaapvaal Craton lithosphere, and this was associated with rifting and the formation of LIPs.

Background Lateral flow device (LFD) viral antigen immunoassays have been developed around the world as diagnostic tests for SARS-CoV-2 infection. They have been proposed to deliver an infrastructure-light, cost-economical solution giving results within half an hour. Methods LFDs were initially reviewed by a Department of Health and Social Care team, part of the UK government, from which 64 were selected for further evaluation from 1st August to 15th December 2020. Standardised laboratory evaluations, and for those that met the published criteria, field testing in the Falcon-C19 research study and UK pilots were performed (UK COVID-19 testing centres, hospital, schools, armed forces). Findings 4/64 LFDs so far have desirable performance characteristics (orient Gene, Deepblue, Abbott and Innova SARS-CoV-2 Antigen Rapid Qualitative Test). All these LFDs have a viral antigen detection of >90% at 100,000 RNA copies/ml. 8951 Innova LFD tests were performed with a kit failure rate of 5.6% (502/8951, 95% CI: 5.1–6.1), false positive rate of 0.32% (22/6954, 95% CI: 0.20–0.48). Viral antigen detection/sensitivity across the sampling cohort when performed by laboratory scientists was 78.8% (156/198, 95% CI 72.4–84.3). Interpretation Our results suggest LFDs have promising performance characteristics for mass population testing and can be used to identify infectious positive individuals. The Innova LFD shows good viral antigen detection/sensitivity with excellent specificity, although kit failure rates and the impact of training are potential issues. These results support the expanded evaluation of LFDs, and assessment of greater access to testing on COVID-19 transmission. Funding Department of Health and Social Care. University of Oxford. Public Health England Porton Down, Manchester University NHS Foundation Trust, National Institute of Health Research.

We report a new paleomagnetic pole for the Black Range Dolerite Suite of dykes, Pilbara craton, Western Australia. We replicate previous paleomagnetic results from the Black Range Dyke itself, but find that its magnetic remanence direction lies at the margin of a distribution of nine dyke mean directions. We also report two new minimum ID-TIMS 207Pb/206Pb baddeleyite ages from the swarm, one from the Black Range Dyke itself (>2769 ± 1 Ma) and another from a parallel dyke whose remanence direction lies near the centre of the dataset (>2764 ± 3 Ma). Both ages are slightly younger than a previous combined SHRIMP 207Pb/206Pb baddeleyite weighted mean date from the same swarm, with slight discordance interpreted as being caused by thin metamorphic zircon overgrowths. The updated Black Range suite mean remanence direction (D = 031.5°, I = 78.7°, k = 40, α95 = 8.3°) corresponds to a paleomagnetic pole calculated from the mean of nine virtual geomagnetic poles at 03.8°S, 130.4°E, K = 13 and A95 = 15.0°. The pole's reliability is bolstered by a positive inverse baked-contact test on a younger Round Hummock dyke, a tentatively positive phreatomagmatic conglomerate test, and dissimilarity to all younger paleomagnetic poles from the Pilbara region and contiguous portions of Australia. The Black Range pole is distinct from that of the Mt Roe Basalt (or so-called ‘Package 1’ of the Fortescue Group), which had previously been correlated with the Black Range dykes based on regional stratigraphy and imprecise SHRIMP U–Pb ages. We suggest that the Mt Roe Basalt is penecontemporaneous to the Black Range dykes, but with a slight age difference resolvable by paleomagnetic directions through a time of rapid drift of the Pilbara craton across the Neoarchean polar circle. (Less)

The volcanic Hartley Formation (part of the Olifantshoek Supergroup, which is dominated by red bed successions) in South Africa recorded depositional and tectonic conditions along the western Kaapvaal Craton during the late Palaeoproterozoic. It formed in association with red bed deposition elsewhere in the cratonic hinterland and along the craton’s northern margin. However, the exact correlation of the Olifantshoek Supergroup with these other red-bed successions is hindered by poor geochronological constraints. Herein, we refine the age and palaeopole of the Hartley Formation, and provide geochronological constraints for large-scale 1.93–1.91 Ga bimodal magmatism on the Kaapvaal Craton (herein named the Hartley large igneous province). We present new age constraints for the mafic and felsic phases of this event at 1923 ± 6 Ma and 1920 ± 4 Ma, respectively, which includes the first reported age dating of the Tsineng Dyke Swarm that has been linked to Hartley volcanism. A mean 1.93–1.91 Ga palaeoma...

On the south-easternmost Kaapvaal Craton, a NE-trending plagioclase-megacrystic dolerite dyke swarm, herein named the White Mfolozi Dyke Swarm (WMDS), has been identified. New U–Pb baddeleyite ages presented here indicate that the WMDS was emplaced within less than 10 million years, with our three most robust results yielding a weighted mean age of 2662 ± 2 Ma. The WMDS is coeval with the youngest dykes of a 2.70–2.66 Ga radiating dyke swarm already identified further north on the eastern side of the Kaapvaal Craton. This dyke swarm radiates out from the eastern lobe of the ca. 2.05 Ga Bushveld Complex. A clustering of ages from the WMDS and the 2.70–2.66 Ga radiating dyke swarm identify potential magmatic peaks at 2701–2692 Ma, 2686–2683 Ma and 2665–2659 Ma. Geochemical signatures of the dykes do not correlate with these age groups, but are rather unique to specific areas. The northern part of the eastern Kaapvaal Craton hosts relatively differentiated 2.70–2.66 Ga dolerite dykes that could have ...

The final fragmentation of Rodinia occurred during the Ediacaran period as the continental blocks of Baltica and Laurentia, as well as Amazonia and West Africa, rifted and drifted apart. It was along this progressively rifted margin that the Iapetus Ocean opened and subsequently closed, creating the Caledonian orogeny (sensu lato), some 100 and 200 million years later. The 0.62–0.54 Ga Central Iapetus Magmatic Province (CIMP), accompanying this break-up, is variously manifested in northern Europe and north-eastern North America as mafic dykes and sills, volcanic rocks, as well as carbonatites. This magmatism is interpreted to be broadly coincident with the so-called Marinoan and Gaskiers glaciations, and the subsequent evolution of metazoans. While the various Precambrian basement blocks of Svalbard are known to carry a Caledonian overprint, the proximity of various parts of Svalbard to either Baltica or Laurentia during final Rodinia breakup in the Ediacaran has yet to be established. Petrographic, geochronological and geochemical data from the variably deformed and metamorphosed coarse-grained mafic units of Oscar II Land (OIIL) from Spitsbergen, Svalbard, are presented here to determine the source of the magma and to elucidate on their palaeogeographic affinity with adjacent crustal blocks/units. An alkali and OIB-like affinity of the mafic units is confirmed by their whole-rock geochemical composition. An ID-TIMS U-Pb baddeleyite crystallisation age determination of 560 ± 12 Ma, obtained from one such mafic unit, contrasts with the published Caledonian (sensu lato) age determinations. These data for OIIL compare well with the broadly coeval and geochemically similar 570–560 Ma Norwegian Seiland Igneous Province, which may have formed a part of Baltica. Temporally and compositionally similar mafic units also occur within the North American Appalachian Belt, as well as the Sept-Iles intrusion, which is part of Laurentia. However, any links between these intrusions with those of Svalbard are yet to be unequivocally demonstrated.

Southeastern Bulgaria is composed of a variety of rocks from pre-Variscan (ca. 0.3 Ga) to pre-Alpine sensu lato (ca. 0.15 Ga) time. The Sakar Unit in this region comprises a series of granitoids and gneisses formed or metamorphosed during these events. It is cut by a series of post-Variscan hydrothermal veins, yet lacks pervasive Alpine deformation. It thus represents a key unit for detecting potential tectonism associated with the enigmatic Cimmerian Orogenic episode, but limited geochronology has been undertaken on this unit. Here we report age constraints on hydrothermal activity in the Sakar Pluton. The investigated veins contain mainly albite&ndash, actinolite&ndash, chlorite&ndash, apatite&ndash, titanite&ndash, quartz&ndash, tourmaline&ndash, epidote and accessory minerals. The most common accessory minerals are rutile and molybdenite. Apatite and titanite from the same vein were dated by U&ndash, Pb LA&ndash, ICP-MS geochronology. These dates are interpreted as crystallization ages and are 149 &plusmn, 7 Ma on apatite and 114 &plusmn, 1 Ma on titanite, respectively. These crystallization ages are the first to document two stages of hydrothermal activity during the late Jurassic to early Cretaceous, using U&ndash, Pb geochronology, and its association with the Cimmerian orogenesis. The Cimmerian tectono-thermal episode is well-documented further to the east in the Eastern Strandja Massif granitoids. However, these are the first documented ages from the western parts of the Strandja Massif, in the Sakar Unit. These ages also temporally overlap with previously published Ar&ndash, Ar and K&ndash, Ar cooling ages, and firmly establish that the Cimmerian orogeny in the studied area included both tectonic and hydrothermal activity. Such hydrothermal activity likely accounted for the intense albitization found in the Sakar Unit.

Mobilistic plate-tectonic interpretation of Precambrian orogens requires that two conjoined crustal blocks may derive from distant portions of the globe. Nonetheless, many proposed Precambrian cratonic juxtapositions are broadly similar to those of younger times (socalled "strange attractors"), raising the specter of bias in their construction. We evaluated the possibility that the Congo and Kalahari cratons (Africa) were joined together prior to their amalgamation along the Damara-Lufilian-Zambezi orogen in Cambrian time by studying diabase dikes of the Huila-Epembe swarm and sills in the southern part of the Congo craton in Angola and in Namibia. We present geologic, U-Pb geochronologic, and paleomagnetic evidence showing that these two cratons were directly juxtaposed at ca. 1.1 Ga, but in a slightly modified relative orientation compared to today. Recurring persistence in cratonic connections, with slight variations from one supercontinent to the next, may signify a style of supercontinental transition similar to the northward motion of Gondwana fragments across the Tethys-Indian oceanic tract, reuniting in Eurasia. (Less)

Precise geochronology, combined with paleomagnetism on mafic intrusions, provides first-order information for paleoreconstruction of crustal blocks, revealing the history of supercontinental formation and break-up. These techniques are used here to further constrain the apparent polar wander path of the Kaapvaal Craton across the Neoarchean-Paleoproterozoic boundary. U-Pb baddeleyite ages of 2441 +/- 6 Ma and 2426 +/- 1 Ma for a suite of mafic sills located on the western Kaapvaal Craton in South Africa (herein named the Westerberg Sill Suite), manifests a new event of magmatism within the Kaapvaal Craton of southern Africa. These ages fall within a ca. 450 Myr temporal gap in the paleomagnetic record between 2.66 and 2.22 Ga on the craton. Our older Westerberg Suite age is broadly coeval with the Woongarra magmatic event on the Pilbara Craton in Western Australia. In addition, the Westerberg Suite on the Kaapvaal Craton intrudes a remarkably similar Archean-Proterozoic sedimentary succession to that on the Pilbara Craton, supporting a stratigraphic correlation between Kaapvaal and Pilbara (i.e., Vaalbara). The broadly coeval Westerberg-Woongarra igneous event may represent a Large Igneous Province. The paleomagnetic results are more ambiguous, with several different possibilities existing. A Virtual Geomagnetic Pole obtained from four sites on the Westerberg sills is 18.9 degrees N, 285.0 degrees E, A(95) = 14.1 degrees, K = 43.4 (Sample based VGP, n=34: 16.8 degrees N, 2879.9 degrees E, dp=4.4 degrees, dm=7.7 degrees). If primary (i.e., 2441-2426 Ma), it would provide a further magmatic event within a large temporal gap in the Kaapvaal Craton's Paleoproterozoic apparent polar wander path. It would suggest a relatively stationary Kaapvaal Craton between 2.44 Ga and 2.22 Ga, and ca. 35 degrees of latitudinal drift of the craton between ca. 2.66 Ga and 2.44 Ga. This is not observed for the Pilbara Craton, suggesting breakup of Vaalbara before ca. 2.44 Ga. However, it is likely that the Woongarra paleopole represents a magnetic overprint acquired during the Ophtalmian or Capricorn Orogeny, invalidating a paleomagnetic comparison with the Westerberg Sill Suite. Alternatively, our Westerberg Virtual Geographic Pole manifests a 2.22 Ga magnetic overprint related to Ongeluk volcanism. The similarity between Ongeluk and Westerberg paleopoles however may also infer magmatic connections if both are primary directions, despite the apparent 200 million year age this difference. (C) 2015 Elsevier B.V. All rights reserved.