trans-Atlantic Correlation Research Articles

The role of crustal-scale shear zones in SW Gondwana consolidation – transatlantic correlation

Abstract We present the first correlation between South American and African shear zones based on a reconstruction model of SW Gondwana continental crust, correlating 57 Brasiliano–Pan-African crustal-scale shear zones that sutured this palaeocontinent at c. 500 Ma. The final amalgamation and consolidation of the SW Gondwana continental crust were attained by an anticlockwise rotation of three cratons (Kalahari, Angola and São Francisco) in relation to the clockwise rotation of the Río de la Plata Craton in the Early Paleozoic. These relative movements were accommodated by transcurrent shear zones active from 585 to 500 Ma within the Pan-African–Brasiliano belts that surround these cratons. This kinematic interaction resulted in the initiation of a long-term active margin starting with the Cambrian Pampean orogeny and ending with the Permian–Triassic Gondwanide orogeny.

Trans-Atlantic correlation of Late Cretaceous high-frequency sea-level cycles

Previous studies of Cretaceous sedimentary rocks have used multi-proxy correlation methods to suggest eustatic change, modulated by the c. 400 kyr long eccentricity rhythm. Although numerous authors have inferred eustatic changes on shorter timescales, none have demonstrated synchronous sea-level changes in separate basins on different plates, thousands of kilometres apart. Our study integrates basin-scale, three-dimensional sequence architecture, molluscan biostratigraphy, and carbon-isotope chemostratigraphy to demonstrate synchronous sea-level changes in upper Turonian to lower Coniacian shallow-marine clastic successions in the Western Canada Foreland Basin, and the Bohemian Cretaceous Basin. Depositional sequences in both basins are plotted in a common time domain using an astronomically calibrated age model, allowing direct comparison. In both basins, at least seven major transgressive events can be shown to be synchronous within the limits of combined biostratigraphic and chemostratigraphic resolution. ‘Major’ and ‘minor’ sequences of late Turonian age appear to have been paced, respectively, by the long (c. 400 kyr) and short (c. 100 kyr) eccentricity cycles. In contrast, early Coniacian sequences evidence pacing by the c. 38 kyr obliquity rhythm. Stratal architecture suggests that sequences developed in response to eustatic changes of c. 14–20 m at average rates ranging 0.08 to >1.3 m/kyr. At a time of ‘warm greenhouse’ climate, sea-level change of this magnitude and timescale may not be explicable entirely as a result of thermal- and aquifer-eustasy, and hence glacio-eustasy may also have been a contributing factor.

Eburnean deformation pattern of Burkina Faso and the tectonic significance of shear zones in the West African craton

Shear zones of the Paleoproterozoic Eburnean accretionary Orogen (West African craton) are investigated by means of large-scale structural mapping. Regional scale (10-100 km) mapping was based on the aeromagnetic survey of Burkina Faso and craton-scale (1000 km) mapping on a compilation of fabric data. At both scales, shear zones are arranged as an anastomosed transpressional network that accommodated distributed shortening and lateral flow of the orogenic lithosphere between the converging Kénéma-Man and Congo Archean provinces. Structural interference patterns at both scales were due to three-dimensional partitioning of progressive transpressional deformation and interactions among shear zones that absorbed heterogeneities in the regional flow patterns while maintaining the connectivity of the shear zone network. Such orogen-scale kinematic patterns call for caution in using the deformation phase approach without considering the “bigger structural picture” and interpreting displacement history of individual shear zones in terms of plate kinematics. The West African shear zone pattern is linked to that of the Guiana shield through a new transatlantic correlation to produce an integrated kinematic model of the Eburnean-Transamazonian orogen.

The low-Ti high-temperature dacitic volcanism of the southern Paraná-Etendeka LIP: Geochemistry, implications for trans-Atlantic correlations and comparison with other Phanerozoic LIPs

The low-Ti silicic volcanic units of the Paraná-Etendeka Large Igneous Province (LIP) have a high volume (~20,000 km3) and are widespread in South America and Africa. In this paper we present a geochemical investigation of conduit- and lava flow-related metaluminous dacitic volcanic rocks from three areas outcropping in southern Brazil. Trace-element abundances are close to those observed from the low-Ti basaltic parental melts and interbedded basaltic andesites. Assimilation and fractional crystallization models suggest significant fractionation (>60%) from basaltic melts with assimilation involving sources with variable large ion lithophiles (LIL) and high field strength (HFS) elements. Variation in Zr/Nb ratios of the silicic volcanic rocks is interpreted to be related to the source characteristics. An effective magma drainage system through structurally controlled conduits was sustained at high magmatic temperatures (~1000–1100 °C), low viscosities of ~106–104 Pa s and water contents from 0.5–1.3 wt%. Melt structures with RAI < 1 are in agreement with field descriptions of an effusive emplacement, erupting domes, coulees, lobes, and extensive SR-type lavas. Trans-Atlantic correlations indicate some compositional overlaps with the Grootberg and Wereldsend quartz latites of Namibia, but the much higher Pb contents of the Namibian quartz latites, five to ten times greater than for the Brazilian dacites, and higher Pb/Cu ratios, suggest a greater degree of assimilation/fractionation of Pb-rich material, such as shale, slate or schist, for the Namibian silicic rocks. After comparing Phanerozoic silicic units related to LIPs, we propose they can be separated into three main types: (1) large volume, high-temperature, water-poor metaluminous rocks, (2) small volume, lower temperature, more hydrous peraluminous to peralkaline rocks; and (3) high-temperature peraluminous rocks with cordierite and garnet, derived from partial melting of metapelitic basement.

Upper Ordovician δ13Corg chemostratigraphy, K-bentonite stratigraphy, and biostratigraphy in southern Scandinavia: A reappraisal

A pioneer δ13Corg study through the upper Sandbian and Katian (Upper Ordovician) succession in the Röstånga 1 drill core in the classical geological outcrop area at Röstånga in southernmost Sweden produced a wealth of new carbon isotope data which are useful for local and regional correlations. Among the Upper Ordovician positive δ13C excursions, the Guttenberg (GICE), Waynesville (Saunja), Whitewater (Moe), Paroveja, and Hirnantian (HICE) isotopic carbon excursions are recognized but the Kope (Rakvere) δ13C excursion is missing, suggesting a stratigraphic gap. All these isotopic excursions are tied closely to biostratigraphy, especially graptolite biostratigraphy, and in the case of the Waynesville (Saunja) and Whitewater (Moe) excursions, for the first time anywhere in the world. The Röstånga GICE δ13Corg curve from the upper Sularp Shale shows a striking similarity to that of the Katian GSSP in Oklahoma, suggesting the potential of trans-Atlantic correlation. Based on a projection from the Katian GSSP, the previously poorly constrained position of the base of the Katian in southern Sweden appears to be in the uppermost Sularp Shale in strata of the upper Diplograptus foliaceus Zone. Previous interpretations of the relations between K-bentonite successions in southern Scandinavia are somewhat revised and the Kinnekulle K-bentonite is recognized for the first time in Scania. Based on new radiometric dates, this very prominent and widespread ash bed appears to be slightly older than the Deicke and Millbrig K-bentonites in eastern North America.

Testing the congruence of the microfossil versus microfossil record in the Turonian–Coniacian boundary succession of the Wagon Mound–Springer composite section (NE New Mexico, USA)

ABSTRACT Walaszczyk, I., Lees, J.A., Peryt, D., Cobban, W.A. and Wood, C.J. 2012. Testing the congruence of the microfossil versus microfossil record in the Turonian-Coniacian boundary succession of the Wagon Mound-Springer composite section (NE New Mexico, USA). Acta Geologica Polonica, 62 (4), 581-594. Warszawa. The Turonian-Coniacian boundary succession from the Wagon Mound-Springer composite section in the US Western Interior shows a virtually identical macrofaunal record to that revealed in the proposed candidate Coniacian GSSP in the Salzgitter-Salder-Słupia Nadbrzeżna composite section in central Europe, with easy identification in both regions of the base of the Coniacian Stage, as defined by the first appearance of the inoceramid bivalve species, Cremnoceramus deformis erectus (Meek). The macrofaunal boundary definition is additionally confirmed by the foraminiferal and nannofossil data, demonstrating the high potential of the inoceramid marker for the base of the Coniacian. The former claims about distinct diachroneity between macrofossil and microfossil dates in the trans-Atlantic correlations, resulted from methodological deficiencies, and have no factual basis.

A new upper Middle Ordovician–Lower Silurian drillcore standard succession from Borenshult in Östergötland, southern Sweden: 2. Significance of δ13C chemostratigraphy

A total of 239 isotope samples are used for establishing the δ13C chemostratigraphy in the upper Middle Ordovician to Lower Silurian succession in the approximately 70 m long Borenshult drillcore. The study interval starts in the upper Darriwilian Furudal Limestone and ends in the Rhuddanian Motala Formation. Four named δ13C excursions are recognized in 3–4 formations, namely the Guttenberg isotope carbon excursion (GICE) in the lower-middle Freberga Formation, the Kope (Rakvere) excursion in the uppermost Freberga Formation and possibly the Slandrom Formation, the Whitewater (Moe) excursion in the Lower Member of the Jonstorp Formation and the Hirnantian isotope carbon excursion (HICE) in the Loka Formation. The Middle Darriwilian isotope carbon excursion (MDICE) is missing in the drillcore and it is suggested that the study succession starts just above the interval of this excursion, which is in agreement with the range of MDICE in other Baltoscandic successions. The widespread Waynesville (Saunja) excursion may be cut out by the prominent unconformity below the Fjäcka Shale. The two most conspicuous excursions are the GICE (peak value ∼+1.9‰) and the HICE (peak value ∼+3.7‰), whereas the other excursions are represented by relatively minor perturbations in the δ13C curve. The Borenshult drillcore chemostratigraphy, which has been closely tied to conodont biostratigraphy, is quite similar to that of Estonian drillcores and is useful for not only trans-Baltic but also trans-Atlantic correlations. It is the first drillcore-based δ13C chemostratigraphy from the Swedish Ordovician.

Palaeomagnetic results from Upper Triassic red-beds and CAMP lavas of the Argana Basin, Morocco

Abstract The continental Argana Basin of Morocco is the trans-Atlantic counterpart of the extensively studied Fundy, Hartford and Newark basins in north-eastern America, that have provided the astrochronologically tuned geomagnetic polarity timescale (GPTS) for the late Triassic and earliest Jurassic. The Argana red-bed successions also show astronomically driven time control, which allowed trans-Atlantic correlations and revealed that the interval towards volcanism of the Central Atlantic Magmatic Province (CAMP) is without any significant hiatuses. Here, we present palaeomagnetic results from the cyclically bedded upper Triassic red-beds and the intercalated volcanics associated with CAMP. Our composite Argana section comprises an interval of 3.5–4.0 Ma, but its magnetostratigraphic pattern does not allow a straightforward correlation to the Newark GPTS. The continental red-bed deposits of the Bigoudine Formation demonstrate a dominant magnetic overprint that could only be removed at temperatures above 600 °C. We suggest that this overprint could have been caused by a period of (Jurassic, c . 170 Ma) magmatism that caused pervasive overprinting of the Triassic palaeomagnetic signal. Correlations between the sections in the Tazantoute region are not straightforward, hampered by the presence of a magmatic sill. The CAMP lava sequences of Tazantoute are all of normal polarity and record secular variation in a manner that agrees with short-lived pulses of CAMP activity in Morocco. Our results indicate that the sedimentary successions of the Argana Basin have the potential to evaluate the Newark GPTS, but that detailed palaeomagnetic analyses of more suitable sections with long(er) cyclostratigraphic records are required.

Katian (Upper Ordovician) δ13C chemostratigraphy and sequence stratigraphy in the United States and Baltoscandia: A regional comparison

δ 13C values of numerous limestone samples from Katian (Upper Ordovician) successions in Oklahoma and the Upper Mississippi Valley document the presence of at least three of the four positive excursions that have been recognized in the lower–middle Katian interval in the Cincinnati region in Ohio, Kentucky, and Indiana. A comparison with Estonia reveals that five out of the six positive excursions now recorded through the Katian succession in the Cincinnati region are present in the coeval stratigraphic intervals in Estonia, which suggests that these represent global perturbations in the carbon cycle. A study of the relations between flooding events and δ 13C excursions shows that only some of the excursions occur in transgressive intervals whereas other excursions are in regressive strata and hence, this is in conflict with the idea that positive carbon isotope excursions are forced by rises in sea level. Part of a previously published attempt to use Upper Ordovician sequence stratigraphy for trans-Atlantic correlation is shown to be seriously out of phase with the biostratigraphy and chemostratigraphy. Several of the sequences recognized in the Cincinnati region do not appear to have counterparts in Estonia, which suggests that they do not reflect eustatic, but local, conditions.

Trans-Atlantic correlation of the Palaeogene volcanic successions in the Faeroe Islands and East Greenland

Before continental break-up in the NE Atlantic, the Faeroe Islands and central East Greenland were within a distance of 100–120 km. Chemical and lithological data for complete sections through the 5 km thick piles of contemporaneous Palaeogene flood basalts in the Faeroe Islands and in the Nansen Fjord area in East Greenland show very similar basalt compositions and evolution patterns with time. The Faeroes lower basalt formation and the equivalent Nansen Fjord Formation in East Greenland form a pre-break-up succession overlain by a sediment horizon. A syn-break-up succession consists of the Faeroes middle and upper basalt formations and the equivalent Milne Land Formation in East Greenland in which five intervals can be correlated with a compositional evolution from Ti-rich magnesian basalts and picrites at the base to a dominance of MORB -like low-Ti basalts at the top. The successions were generated in the same mantle melting column beneath a thinning continent with a rift zone that eventually ruptured the continent. The evolution pattern is very similar to that seen on the SE Greenland margin, but spreading according to the Palmason model of 1973 was not yet established. The pre- and syn-break-up successions formed volcanic megasystems stretching across the rift zone with areal extents of 70 000 and 220 000 km 2 and volumes of 120 000 and 250 000 km 3 . Rocks from the pre- and syn-break-up successions can be discriminated based on a simple major-element plot. The overlying succession was 3–3.5 km thick in E Greenland but was thin or absent in the Faeroes; the energy source for the melting appears to have been concentrated on the Greenland side.

Lower Turonian (Upper Cretaceous) Watinoceras devonenseZone ammonite fauna in Colorado, U S A

The basal Turonian Watinoceras devonense Zone fauna from the Bridge Creek Member of the Greenhorn Limestone in southeastern Colorado is described and illustrated, including material from the Rock Canyon area near Pueblo, where the base of bed 86, which corresponds to the first appearance of W. devonense Wright & Kennedy, 1981, has been proposed as Global Boundary Stratotype Section and Point for the base of the Turonian stage. The fauna includesWatinoceras devonense devonense Wright & Kennedy, 1981, W. depressum Wright & Kennedy, 1981, W. praecursor Wright & Kennedy, 1981, Quitmaniceras reaseri Powell, 1963, Quitmaniceras sp. nov.?,Allocrioceras larvatum (Conrad, 1855), and Hamites cimarronensis (Kauffman & Powell, 1977). A remarkable aspect of the assemblage is the presence of three co-occurring species of Watinoceras that were originally described from Devon, England (Wright & Kennedy, 1981), so that the Watinoceras devonense Zone is a biostratigraphic unit that allows trans-Atlantic correlation of the base of the Turonian Stage.

Trans-Atlantic correlation of eruptive sequences and individual silicic volcanic units within the Paraná-Etendeka igneous province

The Mesozoic volcanic rocks of the Serra Geral Formation in the Paraná Basin, South America, and of the Etendeka Group in northwestern Namibia were erupted shortly before the opening of the South Atlantic. The major widespread silicic volcanic units in the Etendeka Group are interpreted as rheoignimbrites (Milner et al., 1992) and are interbedded with tholeiitic basalts and basaltic andesites. The southern portion of the Etendeka Group is subdivided into a basal Awahab Formation which is overlain disconformably by the Tafelberg Formation. Both formations contain silicic and mafic units. Bulk composition, initial 87Sr 86Sr ratios, phenocryst assemblages and mineral compositions are used to correlate silicic units of the Awahab Formation with the basal units of the Palmas silicic volcanic rocks in the southern Paraná Basin. Silicic units of the Tafelberg Formation can similarly be correlated with silicic units in the upper portion of the Palmas succession, which are also disconformable on the units below them. Not all silicic units in these successions are present in both the Etendeka and Paraná areas, but where correlation of individual units is possible, then this is found to be consistent with the overall stratigraphic sequence. Silicic units in the Awahab Formation were erupted from the Messum Igneous Complex in Namibia and their correlation into Brazil indicates that individual eruptive units must have travelled over 340 km from their source. Serial changes in the composition of silicic units in the Awahab Formation and their correlatives indicates that they were erupted from a single magma system from which a total of ~ 8600 km 3 of material was erupted.

Composition of biotite phenocrysts in Ordovician tephras casts doubt on the proposed trans-Atlantic correlation of the Millbrig K-bentonite (United States) and the Kinnekulle K-bentonite (Sweden)

Biotite phenocryst compositions in three thick, widespread Ordovician K-bentonites, the Deicke and Millbrig from Big Ridge, Alabama, and the Kinnekulle from Mossen, Vastergotland, Sweden, fall into three distinct groups, and so the proposed intercontinental correlation of the Millbrig and the Kinnekulle is suspect. Because the biotites are nearly pristine compositionally, electron microprobe analyses provide a precise geochemical fingerprint of each bed. Millbrig and Kinnekulle biotites contain more FeO* and MnO and less MgO and TiO 2 than do Deicke biotites. Millbrig biotites contain more MgO and less TiO 2 than Kinnekulle biotites, and Kinnekulle biotites contain appreciably more Al 2 O 3 than either Deicke or Millbrig biotites. Each of these tephras was unmistakably the product of a gigantic explosive volcanic eruption, but the differences in phenocryst chemistry point to derivation from three compositionally different magma batches.

The Jurassic-Cretaceous boundary in Northeastern Mexico. Confrontation and correlations by microfacies, clay minerals mineralogy, calpionellids and ammonites

4 profiles, 3 of them in the Sierra Madre Oriental and one 400 km farther NW in the Durango Basin have been measured and sampled in detail, in order to ascertain the stratigraphic position of the boundary between the La Casita and the Taraises Fms. Calpionellids show that this boundary is diachronous, situated in the lower Berriasian. Late Tithonian mediterranean faunal elements are however largely ( Crassicollaria in the case of calpionellids) or completely missing ( Saccocoma, Chitinoidella)). Calpionellids are still more or less sporadic in the lower part of Zone B, but become frequent in its upper part. This indicates an important turnover in oceanographic conditions (currents, and/or temperatures), which appears also clearly in a change of the composition of clay-mineral associations (increase of chlorite, decrease of kaolinite). First analyses of stable oxygen and carbon isotopes point in the same direction, as well as the simultaneous appearance of mediterranean ammonite genera. Calpionellid Zones C to D1 are reduced or incomplete in this part of the Sierra Madre Oriental. The succession of calpionellid faunas corresponds perfectly to that known from the Mediterranean realm. This allows precise transatlantic correlations. It appears that the ammonite genera Durangites and Hildoglochiceras range at least up into the uppermost Tithonian; whereas Kossmatia, Parodontoceras and Substeueroceras extend up into the Berriasian.

Transatlantic correlations in the Campanian-Maastrichtian stages by eustatic changes of sea-level

Abstract There is good evidence that high sea-levels peaked simultaneously during the Late Albian to Turonian in the USA and northwest Europe. Therefore, it is to be expected that the principal peaks during the Campanian-Maastrichtian, now well dated in northwest Europe, should be detectable in the USA. Of the four main peaks in Europe, no. 3, low in the Zone of Belemnitella langei , is the most prominent, and can be recognized with confidence in the Western Interior, New Jersey, Alabama-Mississippi and probably in Texas. The other peaks can be identified with various degrees of confidence, but the sea did not persist long enough in the Western Interior for the last peak, early in the Late Maastrichtian, to be developed there. The results change the generally assumed position of the Campanian-Maastrichtian boundary on the foraminiferal scale: the base of the Maastrichtian on the belemnite scale is a considerable distance above the top of the Zone of Globotruncanita calcarata , possibly as high as the base of the Zone of Gansserina gansseri in north temperate regions. On the ammonite scale in the western interior of the USA the boundary is probably at the base of the Zone of Baculites baculus at 70.7 Ma, but could be at the base of the Zone of B. eliasi .

Appalachian structural trends northeast of Newfoundland and their trans-Atlantic correlation

The tectonostratigraphic zones of Newfoundland have been traced to the continental margin northeast of Newfoundland on the basis of detailed geophysical surveys of the area. The structures of the Avalon zone veer eastward offshore, whereas the western platform and marginal zones trend northerly for approximately 400 k tendency to veer eastward. Using reasonable pre-drift reconstructions on North America and Europe, good correlations are found between the Avalonian units of Newfoundland and Iberia, with the European landfall of the Charlie Fracture zone representing the northern limit of Avalon equivalent basement. Despite the good correlation of the eastern units, the geological elements of western and central Newfoundland, northern Ireland and Scotland, between which geological correlation is “classical”, were separated laterally by approximately 900 km prior to opening of the present Atlantic. This offset of western units but continuity of eastern units is compatible with the existence of an eastward bend in the Appalachian system similar to but larger than the bends of the Appalachian system within the Gulf of St. Lawrence and the eastern United States.

Geophysical study of basement fractures on the western European and eastern Canadian shelves: transatlantic correlations, and late Hercynian movements

Geological interpretation of geophysical data (magnetic, gravimetric and seismic) on the western European and eastern Canadian shelves indicates a transatlantic correlation between the major late Paleozoic fractures of those areas.East–west megafractures, which are primarily grouped in two latitudinal belts at 44° N and 48° N, are the most obvious and correlative. The first zone of fractures was an extension of the South Armorican shear zone, which continued to the north of Flemish Cap. The second was an eastwards extension of the Cobequid–Chedabucto–Scatarie Fault, which crossed Galicia Bank, northern Spain and southern France. A third zone possibly existed between the Clinton–Newbury Fault of New England and mid-Spain, Corsica and Sardinia (when they are moved back to their late Paleozoic positions). The location of the shortening trajectories shows that the first two zones (and perhaps the third one) belonged to the same stress system during late Carboniferous. As a hypothesis, different rates of displacement between 'peri-Atlantic' plates during their northward movement in Late Carboniferous time could be the source of the stress.

Didymograptus bifidus and the trans‐Atlantic correlation of the Lower Ordovician

Bergstrom, S. M. & Cooper, R. A.: Didymograptus bi'us and the trans-Atlantic correlation of the Lower Ordovician. The co-occurrence of Didymograptus bifidus (Hall) and Prioniodus mae Lindstrom, and other conodonts of the middle Arenigian P. mae Zone in the upper part of the Marathon Limestone, Texas, provides the first non-graptolitic evidence that at least part of the D. bifidus Zone, as recognized in the reference area for the standard graptolite zonal succession of the Ordovician of North America, is as old as the BritisK D. nitidus Zone. This has important implications for the correlation of Early Ordovician rocks within North America and across the Atlantic. A regional review of the available evidence from conodonts and shelly megafossils indicates that the D. bifidus—D. artus graptolite assemblage widely used for identification of the D. bifidus Zone in North America ranges in age from the middle Arenigian to, probably, the lower Llanvirnian, and hence is of relatively limited use for precise local and regional correlations. It is also noted that the base of the North American Middle Ordovician falls within hograptus ‘caduceus’ Zone strata that apparently correspond to an interval in the middle to upper part of the British D. hirundo Zone.

Transatlantic Correlation of Miocene Sediments

The Burdigalian/Aquitanian boundary as seen in the Mediterranean region is correlated with the boundary between the Globorotalia fohsi barisanensis subzone and the Globigerinatella insueta zone of southern Trinidad, British West Indies.

Transatlantic Correlation of the Oligo-Miocene by Means of Foraminifera

The successions of Oligo-Miocene zones of planktonic foraminifera are the same on both sides of the Atlantic, but are not synchronous. The same phenomenon has been observed with regard to the Miogypsina sequences. In spite of special difficulties in correlation that are inherent in these groups of organisms, it is fairly certain that a large part of the Central American so-called Oligocene is synchronous with the European early and middle Miocene. Transatlantic correlation of the Oligo-Miocene by means of foraminifera C. W. DROOGER Geological Institute University of Utrecht, Netherlands