scholarly journals Transition in the composition of the Permian clastic rocks in the South Kitakami Terrane, Northeast Japan.

1994 ◽  
Vol 100 (10) ◽  
pp. 744-761 ◽  
Author(s):  
Kohki Yoshida ◽  
Makoto Kawamura ◽  
Hideaki Machiyama
Keyword(s):  
The South ◽  
Clastic Rocks

Evidence for glaciation in the Ordovician rocks of western Ireland

1980 ◽  
Vol 117 (1) ◽  
pp. 81-86 ◽  
Author(s):  
D. M. Williams
Keyword(s):  
Source Area ◽  
The South ◽  
Clastic Rocks ◽  
The Matrix ◽  
Western Ireland ◽  
Glaciogenic Sediments ◽  
New Evidence

SummaryThe Maumtrasna Formation is a thick succession of coarse clastic rocks situated in the South Mayo Trough of western Ireland. Its upperage limit is not defined but it is post-Llanvirn in age and probably Ordovician. Several aspects of the conglomerates within the succession are compatible with the action of a glacial influence during its deposition. New evidence is presented which tends to confirm the glacial hypothesis. 10.7% of garnets separated from the matrix of the conglomerates exhibit chattermark trails. Published accounts of such trails indicate that they are only found in sediments which are glaciogenic or were derived from pre-existing glaciogenic sediments. It is suggested that the Ordovician glacial activity in the South Mayo Trough took the form of a highland glaciation which was maintained, possibly at sub-equatorial latitudes, by a continuous uplift of the source area.

Mélange development in the Boones Point Complex, north-central Newfoundland

1981 ◽  
Vol 18 (3) ◽  
pp. 433-442 ◽  
Author(s):  
K. Douglas Nelson
Keyword(s):  
Debris Flow ◽  
Late Ordovician ◽  
The South ◽  
Upper Ordovician ◽  
North Central ◽  
Clastic Rocks ◽  
The North ◽  
Volcaniclastic Rocks ◽  
Acadian Orogeny

The Boones Point Complex in north-central Newfoundland is a narrow mélange belt separating Roberts Arm terrain volcanic and volcaniclastic rocks to the north from Upper Ordovician westerly derived clastic rocks to the south and east. The mélange has a sedimentary matrix and contains a polymict assemblage of blocks. Limestone blocks have yielded Llanvirn–Llandeilo conodont faunas. Sedimentologic and structural analyses indicate that the complex is composed of subaqueous debris flow deposits, which are the proximal facies equivalent of the Late Ordovician clastics to the south. This debris flow material was tectonically deformed prior to the Medial Devonian 'Acadian' orogeny, probably as a result of earlier 'Taconic' thrusting.

Tectonic evolution of Paleo-Tethys in NE Iran

2021 ◽  
Author(s):  
Yang Chu ◽  
Bo Wan ◽  
Mark B. Allen ◽  
Ling Chen ◽  
Wei Lin ◽  
...  
Keyword(s):  
Subduction Zone ◽  
Foreland Basin ◽  
Passive Margin ◽  
Causal Mechanism ◽  
The South ◽  
Clastic Rocks ◽  
Tethys Ocean ◽  
Depositional Age ◽  
Detrital Zircon Ages ◽  
Ne Iran

<p><span>The timings of the onset of oceanic spreading, subduction and collision are crucial in plate tectonic reconstructions, but not always straightforward to resolve. The evolution of the Paleo-Tethys Ocean dominated the Paleozoic-Early Mesozoic tectonics of West Asia, but the timeline of events is still poorly-constrained. In this study we present detrital zircon ages from NE Iran, in order to determine the timing of tectonic events in the region, and the wider implications for regional tectonics, paleogeography and climate change. Paleozoic clastic rocks record two major age peaks at ~800 Ma and ~600 Ma. The consistency in age patterns shows a dominant provenance from the Neoproterozoic basement of northern Gondwana. We interpret deposition on a long-lasting passive continental margin after the initial spreading of the Paleo-Tethys Ocean. Initial collision between the South Turan (Eurasia) and Central Iran (Gondwana) blocks caused coarse clastic deposition, the protolith of the Mashhad Phyllite, in a peripheral foreland basin on the Paleozoic passive margin. The Mashhad Phyllite yields major zircon age clusters at 450-250 Ma and 1900-1800 Ma, with a clear provenance from the active, Eurasian, margin. The Paleozoic ages reveal a long-lived subduction zone under the South Turan Block began in the latest Ordovician. Analysis of the age spectra allows us to constrain the timing of initial collision as no later than 228 Ma, which is also a constraint on the maximum depositional age of the Mashhad Phyllite. Based on our new results and previous data, we discuss the interaction between the Rheic and Paleo-Tethys oceans, and explain how a new subduction zone may have initiated after continental collision. The timing of collision is similar to the Carnian Pluvial Event (CPE). Paleo-Tethys collision has previously been suggested as the trigger for this climatic change, and our study provides timing evidence that reinforces Paleo-Tethys closure as a causal mechanism for the CPE.</span></p>

scholarly journals The pre‐Vendian (640–610 ma) granite magmatism in the Central Taimyr fold belt: the final stage of the Neoproterozoic evolution of the Siberian paleocontinent active margin

2019 ◽  
Vol 10 (4) ◽  
pp. 841-861
Author(s):  
A. B. Kuzmichev ◽  
M. K. Danukalova ◽  
V. F. Proskurnin ◽  
A. A. Bagaeva ◽  
N. I. Beresyuk ◽  
...  
Keyword(s):  
Deformation Zone ◽  
Field Work ◽  
Point Of View ◽  
The South ◽  
Active Margin ◽  
Porphyritic Granite ◽  
Precambrian Rocks ◽  
Clastic Rocks ◽  
Granite Magmatism ◽  
A Chain

Eastern part of the Central Taimyr belt is composed of Precambrian rocks penetrated by granites of the Snezhnaya complex (845–825 million years) and later overlain by mid‐Neoproterozoic sin‐ postorogenic sedimentary deposits of the Stanovaya‐Kolosova Group. Two competing concepts on the Precambrian history of the belt are dis‐ cussed. The first suggests that by the middle of the Neoproterozoic amalgamation of various terrains formed the Cen‐ tral Taimyr microcontinent, which afterwards collided with Siberia in Vendian. 2) According to the second point of view, which is shared by the authors of this article, the belt was part of the Siberian craton from at least the Mesopro‐ terozoic, and there is no suture that would separate it from the South Taimyr belt. To our surprise, during the field work in the South‐Eastern part of the Central Taimyr belt near the proposed “Vendian sutura”, assumed by the first concept, we found a granite pluton (Pregradnaya massif) intruding clastic rocks of Stanovaya‐Kolosova Group. Such setting is quite uncommon for the belt and contradicted to publications, describing the mentioned clastic rocks to overlay the granites and contain their debris. Dating of the pluton confirmed the field observations – its SRIMP zircon age has proved to be 609±2 Ma, an unusually young for this region. The pluton is located in a wide deformation zone separating the Precambrian rocks (to the northwest) and the Paleozoic deposits (to the southeast). Two minor bodies of similar porphyritic granite were found in the same zone further to the southwest, and it seemed logical to assume that a chain of Vendian granites marks boundary deformation zone. However, their dating (843±6 и 840±5 Ma) showed that they belong to Snezhnaya complex. In this paper, we discuss two Neoproterozoic magmatic ‘flare‐ups’ in the Central Taimyr Belt, which are dated at 845–825 and 640–610 Ma. Both ‘flare‐ups’ are evidenced by K‐rich per‐ aluminous granite batholiths intruded the upper crust. It is most probable that each flare‐up was related to a collision event completing an independent cycle in the evolution of the active margin of the Siberian paleocontinent.

scholarly journals Seismic Structural Analysis of the Alam-El Bueib Formation, Qasr Oil Field, North Western desert, Egypt

2019 ◽  
pp. 20-25
Author(s):  
Farouk I Metwalli ◽  
Mahmoud S Yousif ◽  
Nancy H El Dally ◽  
Ahmed S Abu El Ata
Keyword(s):  
Lower Cretaceous ◽  
Oil Field ◽  
Western Desert ◽  
Normal Faults ◽  
Reverse Fault ◽  
The South ◽  
Late Mesozoic ◽  
Clastic Rocks ◽  
The North ◽  
North Western

The Qasr oil and gas Field is located in the north western desert of Egypt. It belongs to the southeastern part of the Lower Jurassic-Cretaceous Shushan Basin. The Lower Cretaceous Alam-El Bueib formation composed of clastic rocks with noticeable carbonate proportions, and forms multiple oil-bearing sandstone reservoirs in Qasr field. The study aims to define and analyze the Surface and subsurface structural features which are a key issue in assessing reservoir quality. Through this integrated approach, one may be able to identify lithologies and fluids in this region and provide possibly new hydrocarbon fairways for exploration. For this purpose, seismic and well data were interpreted and mapped in order to visualize the subsurface structure of the Cretaceous section. Results show the effect of NE-SW, NW-SE, and E-W trending normal faulting on the Lower Cretaceous Alam-El Bueib formation and is extended to the Upper Cretaceous Abu Roash Formation. The effect of folding is minimal but can be detected. These normal faults are related to the extensional tectonics which affected the north western desert of Egypt during the Mesozoic. One reverse fault is detected in the eastern part and is related mostly to the inversion tectonics in the Late Mesozoic. The depth structure contour maps of the Alam-El Bueib horizons (AEB-1, AEB-3A, and AEB-3D) show several major normal faults trending NE-SW and minor normal faults trending NW-SE. One larger branching normal fault trending E-W and lies to the south of the study area. These step-normal faults divide the area into a number of tilted structural blocks which are shallower in the south and deepen to the north. The area of study was most probably affected by E-W trending normal faults during the opening of the Atlantic Ocean in the Jurassic. Later right-lateral compression resulted from the movement of Laurasia against North Africa, changed their trend into NE-SW faults with minor NW-SE trending folds. These compressive stresses are also responsible for the reverse faulting resulted by inversion in the Late Mesozoic.

scholarly journals Lithogeochemistry of clastic rocks of the Mashak Formation (western slope of the South Urals): in search of “camouflaged” pyroclastics

2020 ◽  
Vol 65 (1) ◽  
pp. 121-145
Author(s):  
Andrey V. Maslov ◽  
◽  
Emir Z. Gareev ◽  
Victor N. Podkovyrov ◽  
Sergey G. Kovalev ◽  
...  
Keyword(s):  
Western Slope ◽  
South Urals ◽  
The South ◽  
Clastic Rocks

scholarly journals New detrital zircon U–Pb insights on the palaeogeographic origin of the central Sanandaj–Sirjan zone, Iran

2021 ◽  
pp. 1-22
Author(s):  
Farzaneh Shakerardakani ◽  
Franz Neubauer ◽  
Xiaoming Liu ◽  
Yunpeng Dong ◽  
Behzad Monfaredi ◽  
...  
Keyword(s):  
South China ◽  
Detrital Zircon ◽  
Sediment Supply ◽  
Detrital Zircons ◽  
South China Block ◽  
The South ◽  
Clastic Rocks ◽  
Gondwana Margin ◽  
Metamorphic Zone ◽  
North Gondwana

Abstract New detrital U–Pb zircon ages from the Sanandaj–Sirjan metamorphic zone in the Zagros orogenic belt allow discussion of models of the late Neoproterozoic to early Palaeozoic plate tectonic evolution and position of the Iranian microcontinent within a global framework. A total of 194 valid age values from 362 zircon grains were obtained from three garnet-micaschist samples. The most abundant detrital zircon population included Ediacaran ages, with the main age peak at 0.60 Ga. Other significant age peaks are at c. 0.64–0.78 Ga, 0.80–0.91 Ga, 0.94–1.1 Ga, 1.8–2.0 Ga and 2.1–2.5 Ga. The various Palaeozoic zircon age peaks could be explained by sediment supply from sources within the Iranian microcontinent. However, Precambrian ages were found, implying a non-Iranian provenance or recycling of upper Ediacaran–Palaeozoic clastic rocks. Trace-element geochemical fingerprints show that most detrital zircons were sourced from continental magmatic settings. In this study, the late Grenvillian age population at c. 0.94–1.1 Ga is used to unravel the palaeogeographic origin of the Sanandaj–Sirjan metamorphic zone. This Grenvillian detrital age population relates to the ‘Gondwana superfan’ sediments, as found in many Gondwana-derived terranes within the European Variscides and Turkish terranes, but also to units further east, e.g. in the South China block. Biogeographic evidence proves that the Iranian microcontinent developed on the same North Gondwana margin extending from the South China block via Iran further to the west.

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