Indication for counterclockwise declination deviation in the Cretaceous of the North Paris Basin

Abstract Paleomagnetic sampling was carried out in Mesozoic exposures of Northwest France and Southeast Belgium. Cretaceous localities in Hainaut, Boulonnais and Normandie yielded statistically well defined paleomagnetic directions. These localities fall into two groups. Hainaut and Boulonnais are characterized by declinations suggesting 30° counterclockwise (CCW) angular deviation of declination with respect to the present North, while Normandie exhibits moderate (12°) clockwise (CW) angular deviation with respect to the present North. In Normandie, we also observed occasionally very weak signals of a CCW deviated component, which, however, could not be treated statistically. Fold test suggests that both groups of samples were remagnetized during deformation. The overall mean paleomagnetic declination of the first group is westernly, that of the second group practically coincides with post-Eocene European reference directions, From assessing structural inversion and relevant paleostress-directions in Normandie, remagnetization may be connected to tectonic inversion in late Eocene-Oligocene times. While the statistically meaningful paleomagnetic result for the second group fit the synthetic stable European apparent polar wander path (APWP) at about 30 Ma, the overall mean paleomagnetic direction of the first group (based on 5 localities, representing 42 samples) defines a pole which is significantly offset from it, at any time following the deposition of the studied sediments. One explanation of this offset could be intraplate rotation on a small (Brabant Massif) scale. However, the angle of deviation in declination seems to be too large for a tectonic solution. Furthermore the data obtained from the Paleozoic do not show such declination deviation. It seems, therefore, that we need to increase considerably the direct stable European paleomagnetic database for the late Cretaceous-Tertiary, in order to further improve the late Cretaceous-Paleogene segment of the European APWP.

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Paleomagnetism of the Lawrenceton Formation volcanic rocks, Silurian Botwood Group, Change Islands, Newfoundland

Canadian Journal of Earth Sciences ◽

10.1139/e89-024 ◽

1989 ◽

Vol 26 (2) ◽

pp. 296-304 ◽

Cited By ~ 10

Author(s):

Julie E. Gales ◽

Ben A. van der Pluijm ◽

Rob Van der Voo

Keyword(s):

North American ◽

Volcanic Rocks ◽

Mobile Belt ◽

Structural Mapping ◽

Polar Wander ◽

The North ◽

Apparent Polar Wander Path ◽

Paleomagnetic Study ◽

North American Craton

Paleomagnetic sampling of the Lawrenceton Formation of the Silurian Botwood Group in northeastern Newfoundland was combined with detailed structural mapping of the area in order to determine the deformation history and make adequate structural corrections to the paleomagnetic data.Structural analysis indicates that the Lawrenceton Formation experienced at least two folding events: (i) a regional northeast–southwest-trending, Siluro-Devonian folding episode that produced a well-developed axial-plane cleavage; and (ii) an episode of local north-trending folding. Bedding – regional cleavage relationships indicate that the latter event is older than the regional folding.Thermal demagnetization of the Lawrenceton Formation yielded univectorial southerly and shallow directions (in situ). A fold test on an early mesoscale fold indicates that the magnetization of the Botwood postdates this folding event. However, our results, combined with an earlier paleomagnetic study of nearby Lawrenceton Formation rocks, demonstrate that the magnetization predates the regional folding. Therefore, we conclude that the magnetization occurred subsequent to the local folding but prior to the period of regional folding.While a tectonic origin for local folding cannot be entirely excluded, the subaerial nature of these volcanics, the isolated occurrence of these folds, and the absence of similar north-trending folds in other areas of eastern Notre Dame Bay suggest a syndepositional origin. Consequently, the magnetization may be nearly primary. Our study yields a characteristic direction of D = 175°, I = +43°, with a paleopole (16°N, 131 °E) that plots near the mid-Silurian track of the North American apparent polar wander path. This result is consistent with an early origin for the magnetization and supports the notion that the Central Mobile Belt of Newfoundland was adjacent to the North American craton, in its present-day position, since the Silurian.

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Paleomagnetism of the komatiitic basalts of the Ottawa Islands, N.W.T.

Canadian Journal of Earth Sciences ◽

10.1139/e85-056 ◽

1985 ◽

Vol 22 (4) ◽

pp. 553-566 ◽

Cited By ~ 2

Author(s):

K. L. Buchan ◽

W. R. A. Baragar

Keyword(s):

North American ◽

Hudson Bay ◽

The West ◽

Magnetization Direction ◽

Polar Wander ◽

The North ◽

Dominant Component ◽

Apparent Polar Wander Path

The komatiitic basalts of the Ottawa Islands in eastern Hudson Bay are on strike with and believed to form a continuation of similar units of the Cape Smith Belt 150 km to the northeast. Units sampled in the Ottawa Islands all dip gently to the west and hence are not suitable for an internal fold test of their age of magnetization. However, before correcting for the tilt of the lavas, the dominant magnetization direction (D = 207.6°, I = 61.9°, k = 168, α95 = 3.7°) does not differ significantly from the uncorrected magnetization direction reported from the steeply dipping, northwest-facing units at Cape Smith (D = 218°, I = 60°, k = 47, α95 = 4°). This negative fold test suggests that the remanence at both locations was acquired after folding. Comparison with the North American Precambrian apparent polar wander path implies that overprinting is related to the Hudsonian Orogeny.A second stable magnetization directed to the west with a shallow inclination is superimposed on the dominant component at a number of sampling sites. Its direction is poorly defined and no fold test is possible. However, magnetic evidence suggests that this component was probably acquired as an overprint after the dominant magnetization, perhaps during a mild reheating associated with the Elsonian Orogeny.

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Pre-Priabonian Palaeogene formations in southwestern Bulgaria and northern Greece: stratigraphy and tectonic implications

Geological Magazine ◽

10.1017/s0016756897008285 ◽

1998 ◽

Vol 135 (1) ◽

pp. 101-119 ◽

Cited By ~ 24

Author(s):

IVAN S. ZAGORCHEV

Keyword(s):

Late Cretaceous ◽

Middle Eocene ◽

Regional Metamorphism ◽

Late Eocene ◽

Thin Layers ◽

The South ◽

Northern Greece ◽

The North ◽

Early Oligocene ◽

Metamorphic Core

The Paril Formation (South Pirin and Slavyanka Mountains, southwestern Bulgaria) and the Prodromos Formation (Orvilos and Menikion Mountains, northern Greece) consist of breccia and olistostrome built up predominantly of marble fragments from the Precambrian Dobrostan Marble Formation (Bulgaria) and its equivalent Bos-Dag Marble Formation (Greece). The breccia and olistostrome are interbedded with thin layers of calcarenites (with occasional marble pebbles), siltstones, sandstones and limestones. The Paril and Prodromos formations unconformably cover the Precambrian marbles, and are themselves covered unconformably by Miocene and Pliocene sediments (Nevrokop Formation). The rocks of the Paril Formation are intruded by the Palaeogene (Late Eocene–Early Oligocene) Teshovo granitoid pluton, and are deformed and preserved in the two limbs of a Palaeogene anticline cored by the Teshovo pluton (Teshovo anticline). The Palaeocene–Middle Eocene age of the formations is based on these contact relations, and on occasional finds of Tertiary pollen, as well as on correlations with similar formations of the Laki (Kroumovgrad) Group throughout the Rhodope region.The presence of Palaeogene sediments within the pre-Palaeogene Pirin–Pangaion structural zone invalidates the concept of a ‘Rhodope metamorphic core complex’ that supposedly has undergone Palaeogene amphibolite-facies regional metamorphism, and afterwards has been exhumed by rapid crustal extension in Late Oligocene–Miocene times along a regional detachment surface. Other Palaeogene formations of pre-Priabonian (Middle Eocene and/or Bartonian) or earliest Priabonian age occur at the base of the Palaeogene sections in the Mesta graben complex (Dobrinishka Formation) and the Padesh basin (Souhostrel and Komatinitsa formations). The deposition of coarse continental sediments grading into marine formations (Laki or Kroumovgrad Group) in the Rhodope region at the beginning of the Palaeogene Period marks the first intense fragmentation of the mid- to late Cretaceous orogen, in particular, of the thickened body of the Morava-Rhodope structural zone situated to the south of the Srednogorie zone. The Srednogorie zone itself was folded and uplifted in Late Cretaceous time, thus dividing Palaeocene–Middle Eocene flysch of the Louda Kamchiya trough to the north, from the newly formed East Rhodope–West Thrace depression to the south.

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The Apparent Polar Wander Path For the North China Block Since the Jurassic

Geophysical Journal International ◽

10.1111/j.1365-246x.1991.tb02492.x ◽

1991 ◽

Vol 104 (1) ◽

pp. 29-40 ◽

Cited By ~ 57

Author(s):

Zhong Zheng ◽

Masaru Kono ◽

Hideo Tsunakawa ◽

Gaku Kimura ◽

Qingyun Wei ◽

...

Keyword(s):

North China ◽

North China Block ◽

Polar Wander ◽

The North ◽

Apparent Polar Wander Path

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First sedimentary record of the pre-obduction convergence in New Caledonia: formation of an Early Eocene accretionary complex in the north of Grande Terre and emplacement of the ‘Montagnes Blanches’ nappe

BSGF - Earth Sciences Bulletin ◽

10.2113/gssgfbull.182.6.479 ◽

2011 ◽

Vol 182 (6) ◽

pp. 479-491 ◽

Cited By ~ 30

Author(s):

Pierre Maurizot

Keyword(s):

Late Cretaceous ◽

New Caledonia ◽

Sedimentary Cover ◽

Planktonic Foraminifera ◽

Foreland Basin ◽

Late Eocene ◽

Passive Margin ◽

Early Eocene ◽

Accretionary Complex ◽

The North

Abstract New Caledonia lies at the northern tip of the Norfolk ridge, a continental fragment separated from the east Gondwana margin during the Late Cretaceous. Stratigraphic data for constraining the convergence that led to ophiolitic nappes being obducted over Grande Terre during the Eocene are both few and inaccurate. To try and fill this gap and determine the onset of the convergence, we investigated the lithology, sedimentology, biostratigraphy and geodynamic context of the Late Cretaceous – Palaeogene sedimentary cover-rock succession of northern New Caledonia. We were able to establish new stratigraphic correlations between the sedimentary units, which display large southwest-verging overfolds detached along a basal argillite series, and reinterpret their interrelationships. The sediments from the Cretaceous-Paleocene interval were deposited in a post-rift pelagic environment and are mainly biogenic with minimal terrigenous input. From the base up, they comprise black organic-rich sulphide-bearing argillite, black chert (silicified equivalent of the argillite), micritic with chert, and micrite rich in planktonic foraminifera. These passive-margin deposits are found regionally on the Norfolk Ridge down to New Zealand, and on the Lord Howe Rise, and were controlled primarily by regional or global environmental factors. The overlying Eocene deposits mark a change to an active-margin regime with distal calciturbidite and proximal breccia representing the earliest Paleogene flysch-type deposits in New Caledonia. The change from an extensional to a compressive regime marks the beginning of the pre-obduction convergence and can be assigned fairly accurately in the Koumac–Gomen area to the end of the Early Eocene (Late Ypresian, Biozone E7) at c 50 Ma. From this period on, the post-Late Cretaceous cover in northern New Caledonia was caught up and recycled in a southwest-verging accretionary complex ahead of which flysch was deposited in a flexural foreland basin. The system prograded southwards until the Late Eocene collisional stage, when the continental Norfolk ridge entered the convergence zone and blocked it. At this point the autochthonous and parautochthonous sedimentary cover and overlying flysch of northern New Caledonia was thrust over the younger flysch to the south to form a newly defined allochthonous unit, the ‘Montagnes Blanches’ nappe, that is systematically intercalated between the flysch and the obducted ophiolite units throughout Grande Terre.

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Paleomagnetism of the Lac St-Jean anorthosite and related rocks, Grenville Province, Quebec

Canadian Journal of Earth Sciences ◽

10.1139/e83-022 ◽

1983 ◽

Vol 20 (2) ◽

pp. 246-258 ◽

Cited By ~ 8

Author(s):

K. L. Buchan ◽

W. F. Fahrig ◽

G. N. Freda ◽

R. A. Frith

Keyword(s):

North American ◽

Regional Metamorphism ◽

The Other ◽

Central Portion ◽

Grenville Province ◽

Polar Wander ◽

Thermal Demagnetization ◽

The North ◽

Apparent Polar Wander Path ◽

Normal Polarity

Alternating field and thermal demagnetization study of the Lac St-Jean anorthosite and related rock units in the central portion of the exposed Grenville Province reveals two components of magnetization, one of reversed and the other of normal polarity. Both components are thought to have been acquired during the last regional metamorphism, which was sufficiently intense in this area (mostly amphibolite grade) to reset any earlier magnetization. Corresponding paleopoles at 193°W, 8°S (dm = 7.3°, dp = 4.6°) and 213°W, 19°S (dm = 10.5°, dp = 8.5°) lie along the 950–900 Ma segment of the recently calibrated Grenville track of the North American apparent polar wander path, a track that has thus far been defined largely by results from rock units of the western Grenville.

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