Faulting of a Middle Jurassic, ultramafic dyke in the Picton Quarry, Picton, southern Ontario

1990 ◽  
Vol 27 (11) ◽  
pp. 1536-1540 ◽  
Author(s):  
G. H. McFall
Keyword(s):  
Fault Zone ◽  
Middle Jurassic ◽  
Southern Ontario ◽  
Prince Edward County ◽  
Dyke Rock ◽  
Tectonic History ◽  
History Of ◽  
East West

A fault zone coinciding with a Middle Jurassic, ultramafic dyke exposed in the Picton Quarry in Prince Edward County, Ontario, is marked by steeply dipping, generally east–west-striking fractures. The dyke has been affected by faulting, as evidenced by the presence of subhorizontal slickensides on fractures cutting the dyke rock. This discovery constitutes the first known example of Middle Jurassic or younger faulting having affected Paleozoic strata of southern Ontario and indicates that the structural and tectonic history of the region is more complex than commonly believed.

Tectonic history of the Queen Charlotte Islands and adjacent areas—a model

1981 ◽  
Vol 18 (11) ◽  
pp. 1717-1739 ◽  
Author(s):  
C. J. Yorath ◽  
R. L. Chase
Keyword(s):  
Fault Zone ◽  
Upper Jurassic ◽  
Normal Faults ◽  
Queen Charlotte Islands ◽  
Tectonic History ◽  
History Of ◽  
Middle Component ◽  
High Level ◽  
Paleozoic Rocks ◽  
Alexander Terrane

The region including Queen Charlotte Islands, Hecate Strait, and Queen Charlotte Sound is underlain by two allochthonous terranes, Wrangellia and the Alexander terrane. The suture between them occurs in central Graham Island and central Hecate Strait and is coincident with the traces of the Sandspit and Rennell Sound fault zones, each of which developed in response to crustal rifting in Queen Charlotte Sound during mid-Tertiary time.The stratigraphic succession comprises four tectonic assemblages. (1) The allochthonous assemblages comprise Paleozoic rocks of the Alexander terrane and Upper Triassic and Jurassic rocks of Wrangellia, which on the basis of paleomagnetic and biogeographical data are clearly exotic. The distribution of these terranes beneath Queen Charlotte Sound and Hecate Strait is supported by geophysical information and subsurface data obtained from offshore wells. (2) The suture assemblage is represented by extremely coarse conglomerates, massive graywackes, and turbidites of Early Cretaceous age, and possibly by Upper Jurassic plutons. (3) The post-suture assemblage is expressed by the tripartite succession of the mid- to Upper Cretaceous Queen Charlotte Group whose middle component, the Honna Formation, comprises polymictic conglomerates that may have resulted from the final accretion of the amalgamated crustal fragments of the Alexander Terrane and Wrangellia to the continental margin. (4) The rift assemblage is expressed by mid- to upper Tertiary volcanics, epizonal plutons, and terrigenous clastics. Rifting is believed to have occurred in Queen Charlotte Sound above a mantle plume and resulted in crustal attenuation through development of listric, crustal-penetrative normal faults, and concurrent extrusion of subaerial volcanics and emplacement of high-level plutons. The attenuation caused northward motion of the Queen Charlotte Islands along the Louscoone Inlet – Sandspit fault zone and subsidence in Queen Charlotte Sound where Lower Miocene marine sediments were deposited within the rift zone. Later, additional rifting in southern Hecate Strait resulted in the reactivation of the old suture zone, manifest as the Rennell Sound fault zone. Concurrent with continued terrigenous deposition and volcanism, the Queen Charlotte Islands moved northwesterly along the Rennell Sound Fault, which disrupted the earlier fault trend. The final rotation of the islands to their modern position was accomplished through left-lateral motion along the Beresford Bay and Langara Faults.

Evidence from Australian mesic zone dung beetles supports their Gondwanan origin and Mesozoic diversification of the Scarabaeinae

2019 ◽  
Vol 50 (2) ◽  
pp. 162-188 ◽  
Author(s):  
Nicole L. Gunter ◽  
Geoff B. Monteith ◽  
Stephen L. Cameron ◽  
Tom A. Weir
Keyword(s):  
Dung Beetles ◽  
Bayesian Analyses ◽  
Tectonic History ◽  
Australian Continent ◽  
History Of ◽  
Climatic History ◽  
Endemic Genera ◽  
Founder Event ◽  
Almost All ◽  
East West

The evolution of dung beetles remains contentious with two hypotheses reflecting Cretaceous and Paleogene origins driven by different methods. We explore biogeographic evidence and phylogeographic origins against vicariance and dispersal scenarios that attribute to the four elements of the Australian fauna using a multi-gene approach. Maximum-likelihood and Bayesian analyses supported the Australasian clade, composed of almost all Australian, New Caledonian and New Zealand endemic genera (to the exclusion of Boletoscapter). Two Australian lineages with east-west splits and few lineages with restricted, non-overlapping distrbution were identified, and biogeography models provided evidence that vicariance and founder event speciation are important processes in the diversification of Australasian scarabaeines. Our phylogenetic results are largely congruent with a mid-Cretaceous origin of the Australasian clade, the tectonic history of Gondwanaland and climatic history of the Australian continent, and provide compelling evidence that Australian dung beetles are a relictual fauna whose history is linked to mesic zone fragmentation.

scholarly journals A Rb-Sr age and isotope study of the Ikertôq, Nordre Strømfjord, and Evighedsfjord shear belts, West Greenland - outline and preliminary results

1979 ◽  
Vol 89 ◽  
pp. 125-128
Author(s):  
M.H Hickman
Keyword(s):  
Shear Zone ◽  
Tectonic History ◽  
Time Period ◽  
Intrusive Rocks ◽  
History Of ◽  
Isotope Study ◽  
Intense Deformation ◽  
Preliminary Study ◽  
Isotope System ◽  
East West

In the 1977 and 1978 field seasons, samples were collected from both the Ikertôq and Nordre Strømfjord shear belts and adjacent unsheared terrains. The samples represent the main rock-forming and shear zone-forming events in these two areas. In addition, samples for preliminary study were collected by S. B. Jensen and J. Allaart from sheared and unsheared gneisses in the Evighedsfjord region. Rb-Sr total rock analyses will be carried out on all samples. Suitably banded samples of both sheared and unsheared gneisses will be cut along compositionallayering to examine the Rb-Sr system on a small whole rock scale. The main Sr-bearing mineral phases of samples throughout the study area will also be analyzed. The purpose of this study is threefold. First, it will establish the geochronological frarnework of the main rock-forming and shear zone-forming events in this region. Second, it will help to clarify the thermo-tectonic history of the study area (especially in its first stages), mainly through the use of Rb-Sr mineral analyses. Two mineral age traverses will be produced, one north-south traverse along the coast between Agto and Evighedsfjord, and another east-west traverse from the coast 70 km inland along Nordre Strømfjord. The third aim of the study is to investigate the response of the Rb-Sr isotope system to intense deformation in the shear belts. This region lends itseif to such an investigation for two main reasons: (a) the age(s) of deformation ean be independently established using synto late-tectonic intrusive rocks; (b) the time period between the origin of the gneisses and the formation of the shear belts is long, from several hundred to 1000 m.y., and thus sufficient for significant isotopic heterogeneity to develop prior to deformation.

scholarly journals Tectonic History of the South Tannuol Fault Zone (Tuva Region of the Northern Central Asian Orogenic Belt, Russia): Constraints from Multi-Method Geochronology

Minerals ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 56
Author(s):  
Evgeny Vetrov ◽  
Johan De Grave ◽  
Natalia Vetrova ◽  
Fedor Zhimulev ◽  
Simon Nachtergaele ◽  
...  
Keyword(s):  
Fault Zone ◽  
Volcanic Rocks ◽  
The South ◽  
Mafic Rocks ◽  
Tectonic History ◽  
Central Asian ◽  
Igneous Provinces ◽  
Late Neogene ◽  
History Of ◽  
Felsic Volcanic

In this study, we present zircon U/Pb, plagioclase and K-feldspar 40Ar/39Ar and apatite fission track (AFT) data along the South Tannuol Fault Zone (STFZ). Integrating geochronology and multi-method thermochronology places constraints on the formation and subsequent reactivation of the STFZ. Cambrian (~510 Ma) zircon U/Pb ages obtained for felsic volcanic rocks date the final stage of STFZ basement formation. Ordovician (~460–450 Ma) zircon U/Pb ages were obtained for felsic rocks along the structure, dating their emplacement and marking post-formational local magmatic activity along the STFZ. 40Ar/39Ar stepwise heating plateau-ages (~410–400 Ma, ~365 and ~340 Ma) reveal Early Devonian and Late Devonian–Mississippian intrusion and/or post-magmatic cooling episodes of mafic rocks in the basement. Permian (~290 Ma) zircon U/Pb age of mafic rocks documents for the first time Permian magmatism in the study area creating prerequisites for revising the spread of Permian large igneous provinces of Central Asia. The AFT dating and Thermal history modeling based on the AFT data reveals two intracontinental tectonic reactivation episodes of the STFZ: (1) a period of Cretaceous–Eocene (~100–40 Ma) reactivation and (2) the late Neogene (from ~10 Ma onwards) impulse after a period of tectonic stability during the Eocene–Miocene (~40–10 Ma).

Tectonic history of the Dent Blanche

2017 ◽  
Vol 9 (2.1) ◽  
pp. 1-73 ◽  
Author(s):  
Paola Manzotti ◽  
Michel Ballèvrei
Keyword(s):  
Tectonic History ◽  
History Of

Tertiary tectonic history of the Salawati area, Irian Jaya, Indonesia

2018 ◽  
Author(s):  
C.M. Froidevaux
Keyword(s):  
Irian Jaya ◽  
Tectonic History ◽  
History Of
Sign in / Sign up

Export Citation Format

Share Document