Initial rifting and breakup between Nova Scotia and Morocco: insight from new magnetic models 1This article is one of a series of papers published in this CJES Special Issue on the theme of Mesozoic–Cenozoic geology of the Scotian Basin. 2Earth Sciences Sector Contribution 20120024.

2012 ◽  
Vol 49 (12) ◽  
pp. 1385-1394 ◽  
Author(s):  
Sonya A. Dehler
Keyword(s):  
Nova Scotia ◽  
Magnetic Anomaly ◽  
Late Triassic ◽  
Magnetic Data ◽  
Supporting Evidence ◽  
The North ◽  
New Models ◽  
Basin Geometry ◽  
Thinned Continental Crust ◽  
High Degree

New models of magnetic data are presented that provide insight into the early stages of rifting and breakup between Morocco and Nova Scotia. The margins, which began forming during the Late Triassic rifting and Middle Jurassic separation of the North American and African plates, display considerable variability in deeper crustal structure, faulting style, and basin geometry along their length. The central and northeastern portions of the Nova Scotia margin show characteristics of a magma-poor margin, with a high degree of crustal thinning and a complex ocean-continent transition zone with little direct evidence of volcanism. In contrast, the margin to the southwest of Nova Scotia has clearly recognized characteristics of a volcanic-style rifted margin, including seaward-dipping reflector (SDR) sequences that are interpreted as rift-related volcanic flows overlying basement. These SDRs are coincident with a strong linear magnetic anomaly, the East Coast Magnetic Anomaly (ECMA), which shares many characteristics with the West African Coast Magnetic Anomaly (WACMA). Both magnetic anomalies change character and diminish in amplitude northward along the margins. The new models show the expected decrease in magnetic source material towards the northeastern end of the margin and suggest that modest amounts of igneous material, emplaced at or near the edge of the thinned continental crust, will satisfy the observed anomalies in this magma-poor section of the margin. These new interpretations and supporting evidence indicate volcanism was a factor along much of the margin during early rifting between Nova Scotia and Morocco.

U.S. National Magnetic Anomaly Survey Specifications Workshop Report

Geophysics ◽  
1979 ◽  
Vol 44 (5) ◽  
pp. 991-992
Author(s):  
William J. Hinze
Keyword(s):  
Magnetic Anomaly ◽  
North American ◽  
Executive Committee ◽  
Ad Hoc ◽  
Magnetic Data ◽  
Aeromagnetic Data ◽  
Workshop Report ◽  
The North ◽  
Anomaly Map ◽  
The U.S

The National Magnetic Anomaly Map (NMAM) Committee, which was formed as an ad hoc committee in 1975 by the SEG Executive Committee, has recommended a multistage program for improving the aeromagnetic data of the U.S. On behalf of the geoscience community, the committee and the U.S. Geological Survey are currently engaged in the preparation of a photo‐composite map of the U.S. derived from publicly available data plus regional magnetic data contributed from the private sector. This map is at present being compiled and is to be pulished by the U.S.G.S. at a scale of [Formula: see text]. Eventually, utilizing this map, the committee plans to assist in the preparation of a North American magnetic anomaly map to supplement the North American tectonic map and the proposed continental gravity anomaly map.

scholarly journals From continental platform towards rifting of the Tisza Unit in the Late Triassic to Early Cretaceous

2013 ◽  
Vol 64 (4) ◽  
pp. 279-290 ◽  
Author(s):  
Géza Császár ◽  
Balázs Szinger ◽  
Olga Piros
Keyword(s):  
Middle Jurassic ◽  
Middle Triassic ◽  
Rift Zone ◽  
Patch Reef ◽  
Upper Jurassic ◽  
Late Triassic ◽  
The North ◽  
Marine Carbonates ◽  
Points Of View ◽  
Thinned Continental Crust

Abstract The Upper Triassic-Lower Cretaceous successions of the Transdanubian part of the Mecsek and Villány- Bihor Zones of the Tisza Unit have been studied from the lithological, lithostratigraphical, sedimentological, microfossil and microfacies points of view in order to correlate and interpret the significant differences between them and to draw a conclusion about their geological and paleogeographical history. After an overview of the paleogeographical reconstructions of the broader area, the succession of the Mecsek and Villány-Bihor Zones and the debated Máriakéménd-Bár Range are introduced. Until the end of the Middle Triassic the study area acted as an entity. The first fundamental difference between the two zones can be recognized in the Late Triassic when marine carbonates were replaced by thick fluvial siliciclastics in the Mecsek Zone, while it is represented only by small, local lenses with a few and thin dolostone intercalations in the Villány Zone. The Mecsek Zone is bordered southward by one of the large listric faults to the north of which very thick siliciclastics developed in the Early to Middle Jurassic, whereas it is highly lacunose in the larger western part of the Villány-Bihor Zone. The break at the base is subaerial, higher in the succession it is shallow submarine. The sediment is silty, occasionally sandy crinoidal limestone of late Early Jurassic or even Middle Jurassic in age. The Upper Jurassic in the Mecsek Zone is composed of deep-water cherty limestone while in the Villány Zone it became a thick, shallowing pelagic limestone with reworked patch reef fragments. It is clear evidence that the Mecsek Zone had a thinned continental crust thanks to the nearby rift zone while in the Villány Zone the crust remained thick. The actualized version of the Plašienka’s paleogeographical model (Plašienka 2000) is introduced

scholarly journals Plate tectonic reconstructions and paleogeographic maps of the central and North Atlantic oceans 1This article is one of a series of papers published in this CJES Special Issue on the theme of Mesozoic–Cenozoic geology of the Scotian Basin. 2Earth Sciences Sector Contribution 20120172.

2012 ◽  
Vol 49 (12) ◽  
pp. 1395-1415 ◽  
Author(s):  
Jean-Claude Sibuet ◽  
Stéphane Rouzo ◽  
Shiri Srivastava
Keyword(s):  
Nova Scotia ◽  
North America ◽  
Magnetic Anomaly ◽  
Late Cretaceous ◽  
North Atlantic ◽  
West African ◽  
Late Triassic ◽  
West African Coast ◽  
African Coast ◽  
Salt Deposits

We have established a new plate kinematic model of the central and North Atlantic oceans between North America, Africa, Meseta, Iberia, Flemish Cap, and Galicia Bank from Late Triassic to Late Cretaceous to better understand the nature and timing of rifting of Nova Scotia and Morocco conjugate continental margins since Late Triassic. The maps of salt distributions at the Sinemurian–Pliensbachian limit (190 Ma; after salt deposition) and in middle Bajocian (170 Ma) show that an area of the Nova Scotia margin is devoid of allochthonous salt and that an area of similar size located oceanward of the West African Coast Magnetic Anomaly shows salt deposits, suggesting that a portion of the Nova Scotia margin with its overlying salt deposits could have been transferred onto the Moroccan side right after the formation of the conjugate East Coast Magnetic Anomaly and West African Coast Magnetic Anomaly. Seven paleogeographic maps, from Late Triassic to Late Cretaceous, are presented with structural elements and magnetic lineations. They show that the connection between the Central Atlantic and the Tethys, with an aborted rift between Iberia and North America ending in the north against the Flemish Cap – Galicia Bank dam, started to deepen at the end of the first rifting phase (190 Ma ago) after the rupture of the thinned continental crust. It is only during the Early Cretaceous, after the rupture of the Flemish Cap – Galicia Bank dam, that the deep connection around Iberia was finally established between the Central and North Atlantic, the Tethys, and the Bay of Biscay.

Geochemical discriminators and the palaeotectonic environment of the North Mountain basalts, Nova Scotia

1980 ◽  
Vol 17 (12) ◽  
pp. 1740-1745 ◽  
Author(s):  
J. M. Wark ◽  
D. B. Clarke
Keyword(s):  
Nova Scotia ◽  
Continental Crust ◽  
Early Jurassic ◽  
Late Triassic ◽  
Chemical Characteristics ◽  
Sea Floor ◽  
The North ◽  
Sea Floor Spreading

The late Triassic – early Jurassic North Mountain basalts of Nova Scotia have been analyzed for various elements believed to be useful in determining the palaeotectonic environment of eruption. The discriminant diagrams show these basalts to have within-plate affinities, with a possible indication of oceanic chemical characteristics. An oceanic environment, however, is at variance with the field relations, which show the within-plate environment to be continental; thus the oceanic chemical characteristics may suggest eruption through a continental crust that was thinning prior to the onset of active sea-floor spreading later in the Jurassic.

Insights into the Red Sea area from magnetic and gravity analysis

2021 ◽  
Author(s):  
Ran Issachar ◽  
Jörg Ebbing ◽  
Dilixiati Yixiati ◽  
Nils Holzrichter
Keyword(s):  
Magnetic Anomaly ◽  
Red Sea ◽  
Magnetic Measurements ◽  
Magnetic Data ◽  
Lithosphere Structure ◽  
The North ◽  
Southern Central ◽  
Anomaly Map ◽  
Sea Floor Spreading ◽  
Sea Area

<p>We explore the lithosphere structure of the Red Sea using gravity and magnetic data.</p><p>We re-processed marine data form past surveys conducted during the 70’s and the 80’s, available at the NGDC database. By correcting the magnetic measurements according to the DGRF (definitive magnetic reference field), leveling and replacing the long wavelengths with satellite data (LCS1 model) we managed to generate a consistent magnetic anomaly map for the entire length of the Red Sea that is composed of 10 different surveys and contain overs 100,000 measuring points. The magnetic anomaly map highlights structural differences between the southern, central and northern parts of the Red Sea.</p><p>Using forward gravity approach, constrains from seismic, wells and petrophysical data, and by integrating insights from magnetic analysis, we define the lithospheric model of the Red Sea to address key questions regarding rifting, sea floor spreading and transition processes.  For example, the southern parts of the Red Sea are characterized by shallow and wide asthenosphere upwelling, while in the axial trough lithosphere is thin with thicknesses of less than 15 km. The lithosphere thickness increase asymmetrically towards the rift shoulders. In general, the lithosphere is thicker on the eastern sides than on the western sides. In the central parts of the Red Sea, the lithosphere structure is not significantly different from the southern parts, however, asthenosphere upwelling is slightly narrower. In northern parts of the Red Sea asthenosphere upwelling significantly narrows and focused mainly beneath the axial trough and the lithosphere is thicker. This architecture reflects the currently transition from continental rifting (in the north) to oceanic seafloor spreading (in the south) in the Red Sea.</p>

K–Ar isochron age and paleomagnetism of diabase along the trans-Avalon aeromagnetic lineament—evidence of Late Triassic rifting in Newfoundland

1980 ◽  
Vol 17 (4) ◽  
pp. 491-499 ◽  
Author(s):  
J. P. Hodych ◽  
A. Hayatsu
Keyword(s):  
Nova Scotia ◽  
Early Jurassic ◽  
Late Triassic ◽  
The North ◽  
Two Samples ◽  
Avalon Peninsula

A prominent aeromagnetic lineament crosses the Avalon Peninsula of Newfoundland from 46°50.4′N, 53°45.9′W to 47°22.1′N, 52°30.0′W. It is shown to be at least partly caused by diabase dikes of Late Triassic and possibly Early Jurassic age which are probably related to the Shelburne diabase dike and the North Mountain basalt, both of Nova Scotia. All are thought to have resulted from rifting which preceded opening of the Atlantic.Unmetamorphosed diabase was found at three sites along the trans-Avalon aeromagnetic lineament: as narrow sills at site 1 (46°58.0′N, 53°25.4′W), as a narrow dike at site 2 (47°4.7′N, 53°7.6′W), and as large angular boulders at site 3 (47°11.0′N, 52°52.2′W).For sites 1 and 2, analyses of seven diabase samples fall on a single K–Ar isochron whose intercept on the 40Ar/36Ar axis is at 215 ± 45 and whose slope gives a Late Triassic age of 201.1 ± 2.6 Ma. Analyses of two diabase samples from the Shelburne dike fall close to this isochron suggesting a similar age. Paleomagnetism adds support; the virtual paleopole measured for sites 1 and 2, using 12 oriented diabase samples demagnetized in 300 Oe (23 880 A/m) alternating field (AF), falls at 87.8°E, 72.9°N (dp = 3.0°, dm = 4.3°), close to the virtual paleopole reported for the Shelburne dike.For site 3, analyses of two samples fall on the K–Ar isochron reported for the North Mountain basalt, tentatively suggesting that the intrusion at site 3 occurred about 10 Ma later than at sites 1and 2.

Subsurface stratigraphy and basin-fill architecture of the late Paleozoic eastern Taos trough, northern New Mexico, U.S.A.

2020 ◽  
Vol 57 (3) ◽  
pp. 149-176
Author(s):  
Nur Uddin Md Khaled Chowdhury ◽  
Dustin E. Sweet
Keyword(s):  
New Mexico ◽  
Sediment Accumulation ◽  
Late Paleozoic ◽  
North Central ◽  
The North ◽  
Basement Rocks ◽  
Basin Geometry ◽  
Deformation Event ◽  
Thrust System ◽  
Basin Fill

The greater Taos trough located in north-central New Mexico represents one of numerous late Paleozoic basins that formed during the Ancestral Rocky Mountains deformation event. The late Paleozoic stratigraphy and basin geometry of the eastern portion of the greater Taos trough, also called the Rainsville trough, is little known because the strata are all in the subsurface. Numerous wells drilled through the late Paleozoic strata provide a scope for investigating subsurface stratigraphy and basin-fill architecture of the Rainsville trough. Lithologic data obtained predominantly from petrophysical well logs combined with available biostratigraphic data from the greater Taos trough allows construction of a chronostratigraphic framework of the basin fill. Isopach- and structure-maps indicate that the sediment depocenter was just east of the El Oro-Rincon uplift and a westerly thickening wedge-shaped basin-fill geometry existed during the Pennsylvanian. These relationships imply that the thrust system on the east side of the Precambrian-cored El Oro-Rincon uplift was active during the Pennsylvanian and segmented the greater Taos trough into the eastern Rainsville trough and the western Taos trough. During the Permian, sediment depocenter(s) shifted more southerly and easterly and strata onlap Precambrian basement rocks of the Sierra Grande uplift to the east and Cimarron arch to the north of the Rainsville trough. Permian strata appear to demonstrate minimal influence by faults that were active during the Pennsylvanian and sediment accumulation occurred both in the basinal area as well as on previous positive-relief highlands. A general Permian decrease in eustatic sea level and cessation of local-fault-controlled subsidence indicates that regional subsidence must have affected the region in the early Permian.

Lithospheric modification at the onset of the destruction of the North China Craton: Evidence from Late Triassic mafic dykes

2021 ◽  
Vol 566 ◽  
pp. 120105
Author(s):  
Chao Wang ◽  
Shuguang Song ◽  
Li Su ◽  
Mark B. Allen ◽  
Jinlong Dong
Keyword(s):  
North China Craton ◽  
North China ◽  
Late Triassic ◽  
Mafic Dykes ◽  
The North
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