Upper Triassic Barranca Group; Nonmarine and shallow-marine rift-basin deposits of northwestern Mexico

1991 ◽  
pp. 19-36 ◽  
Author(s):  
John H. Stewart ◽  
Jaime Roldán-Quintana
Keyword(s):  
Upper Triassic ◽  
Rift Basin ◽  
Shallow Marine ◽  
Northwestern Mexico

scholarly journals SEDIMENTOLOGY AND BIOSTRATIGRAPHY OF AN UPPER TRIASSIC CARBONATE SUCCESSION OF TRIPOLITZA PLATFORM IN MARI AREA, PARNON MOUNTAIN, SE PELOPONNESUS, GREECE

2018 ◽  
Vol 40 (1) ◽  
pp. 101
Author(s):  
M. Kati ◽  
A. Zambetakis-Lekkas ◽  
E. Skourtsos
Keyword(s):  
Carbonate Platform ◽  
Upper Triassic ◽  
Shallow Marine ◽  
Carbonate Sedimentation ◽  
Subaerial Exposure ◽  
Arid Conditions ◽  
Southern Margin ◽  
Time Period ◽  
Marine Carbonate ◽  
Semi Arid

The Upper Triassic succession in the base of Tripolitza carbonate platform, in the Mari area of the Parnon Mt. in SE Peloponnesus, mostly consists of dolomites and to a lesser extent ofcalcitic dolomites. A detailed fades analysis and biostratigraphical study revealed that during Norian — Rhaetian times inter-supratidal and subtidal (shallow lagoonal) fades presenting cyclic development were deposited in the inner platform, similar to those that were formed in most of the Alpine platforms of the southern margin of the Tethys during the same time period. Diagenetic considerations further indicate that this shallow marine carbonate sedimentation was interrupted by subaerial exposure intervals and subsequent early lithification of the recently deposited sediments. The extensive and, mainly, early dolomitization and recrystallization, the presence of meteoric-vadose cements and specifically the repeated appearance of dolocrete horizons in the upper parts of many peritidal cycles, clearly show periodic subaerial exposure of the sediments, as well as the prevalence of semi-arid conditions in the area.

scholarly journals Dinoflagellate cysts from the Upper Triassic (Norian) of northeastern Iran

2008 ◽  
Vol 27 (2) ◽  
pp. 125-134 ◽  
Author(s):  
Ebrahim Ghasemi-Nejad ◽  
Martin J. Head ◽  
Maryam Zamani
Keyword(s):  
World Wide ◽  
Sedimentary Facies ◽  
Upper Triassic ◽  
Late Triassic ◽  
Dinoflagellate Cysts ◽  
Shallow Marine ◽  
Marine Deposits ◽  
Northwest Europe ◽  
Near Shore ◽  
Early Late

Abstract. Upper Triassic (Norian) strata of the Miankuhi Formation in northeastern Iran have been studied palynologically, revealing a diverse but poorly preserved association of dinoflagellate cysts. Based on representatives of the genera Hebecysta, Heibergella, Rhaetogonyaulax and Sverdrupiella, the strata are assigned to the middle of the Hebecysta balmei Zone with an inferred age of early Late Norian. The association shows similarities with assemblages from Australia, New Zealand, Indonesia, Northwest Europe, arctic Canada and Alaska, indicating an interconnection of warm Tethyan waters during the Late Triassic. The occurrence of Sverdrupiella species in the clastic, near-shore marine deposits of Miankuhi, and their presence in similar sedimentary facies world-wide, indicate that this genus was well adapted to clastic shallow-marine environments.

Initiation and evolution of forearc basins in the Central Myanmar Depression

2019 ◽  
Vol 132 (5-6) ◽  
pp. 1066-1082 ◽  
Author(s):  
Fulong Cai ◽  
Lin Ding ◽  
Qinghai Zhang ◽  
Devon A. Orme ◽  
Honghong Wei ◽  
...  
Keyword(s):  
Detrital Zircon ◽  
Upper Cretaceous ◽  
Upper Triassic ◽  
Forearc Basin ◽  
The West ◽  
Zircon Age ◽  
Shallow Marine ◽  
Western Margin ◽  
Forearc Basins ◽  
Structural High

Abstract The forearc basin in Myanmar is significant in understanding the development of continental forearc basins. We present stratigraphic, sandstone petrographic, and U-Pb detrital data from Upper Cretaceous–Eocene strata of Chindwin and Minbu sub-basins in the Central Myanmar Depression. The Upper Cretaceous lower Kabaw Formation consists of turbiditic conglomerate, sandstone, and mudstone in the Minbu sub-basin. The composition of conglomerates are mainly schist and subordinate quartz. Prominent detrital zircon age probability peaks are between 260 and 223 Ma, similar with that of Upper Triassic Pane Chaung turbidites and Kanpetlet schist on the West Burma plate. In the upper Kabaw Formation, turbiditic volcanic-rich sandstones have major age populations ranging from 103 to 70 Ma in both Minbu and Chindwin sub-basins. The Paleocene slope environment Paunggyi Formation, which overlies the Kabaw Formation, mainly consists of conglomerate, sandstone, mudstone, and tuff beds in the Minbu sub-basin. In contrast, the Paunggyi Formation in the Chindwin sub-basin is composed of sandstone and mudstone; major detrital zircon age populations from the Paunggyi Formation are between 100 and 60 Ma. Eocene strata in both basins are composed mainly of shallow marine to delta sandstone and mudstone. Major detrital zircon age populations are 100–36 Ma and 600–500 Ma. The Late Cretaceous–Eocene ages from Upper Cretaceous–Eocene strata overlap with igneous crystallization ages from the Western Myanmar Arc. We propose that the Chindwin and Minbu sub-basins developed as parts of a forearc basin along the west flank of Western Myanmar Arc (present coordinate). The forearc basin initiated in Albian time atop the continental West Burma plate due to the formation of a structural high along the western margin of West Burma plate.

The first Upper Triassic silicified hypercalcified sponges from the Alexander Terrane, Gravina island and Keku Strait, Southeast Alaska

2008 ◽  
Vol 82 (2) ◽  
pp. 344-350 ◽  
Author(s):  
Baba Senowbari-Daryan ◽  
Andrew H. Caruthers ◽  
George D. Stanley
Keyword(s):  
North America ◽  
Great Basin ◽  
Upper Triassic ◽  
Western North America ◽  
Southeast Alaska ◽  
Cassian Formation ◽  
Nayband Formation ◽  
Northwestern Mexico ◽  
Alexander Terrane

This paper describes the first silicified Upper Triassic (Early Norian) hypercalcified sponges known from the Alexander terrane, southeast Alaska. Sponges consist of five taxa from the Cornwallis Limestone of Keku Strait, southeast Alaska: Amblysiphonella Steinmann, Parauvanella Senowbari-Daryan and Di Stefano, Nevadathalamia cylindrica (Seilacher), N. minima n. sp., and Stellispongia (S. cf. subsphaerica Dieci, Antonacci, and Zardini). The hypercalcified sponges of the Alexander terrane as described in this paper provide paleogeographic linkage with other far-flung terranes of western North America, namely the Western Great Basin of Nevada, Stikinia of the Yukon, as well as the Antimonio terrane of northwestern Mexico. In addition, Parauvanella cf. ferdowensis is known from the Upper Triassic Nayband Formation, Iran. Finally Stellispongia cf. subsphaerica is known from the Upper Carnian Cassian Formation of the Dolomite Alps.Sponges (particularly hypercalcified inozoans, sphinctozoans, chaetetids, and sponge-like organisms) are known worldwide from many Upper Triassic reef and nonreef sites. Although Upper Triassic deposits within the Cordilleran terranes and cratonal North America do not typically contain reeflike buildups, hypercalcifying sponge-like organisms were noted as occurring as part of the intricate paleoecological structure within a biostrome along the western shoreline of Gravina Island, southeast Alaska (southern Alexander terrane). This is in contrast to Keku Strait, southeast Alaska (central Alexander terrane), where hypercalcified sponges were identified from limestone beds within nonreef deposits.

scholarly journals Glauconitic deposits at Julegård on the south coast of Bornholm, Denmark dated to the Cambrian

2011 ◽  
Vol 59 ◽  
pp. 1-12
Author(s):  
Lars B. Clemmensen ◽  
Richard G. Bromley ◽  
Paul Martin Holm
Keyword(s):  
Lower Cambrian ◽  
Trace Fossils ◽  
Upper Triassic ◽  
South Coast ◽  
The South ◽  
Shallow Marine ◽  
Marine Deposits

Bioturbated, glauconitic siltstones and sandstones are overlain by presumed Upper Triassic deposits at coastal exposures at Julegård on the south coast of Bornholm. These glauconitic deposits have not previously been dated. A 40Ar-39Ar dating of the glaucony gives an age of 493 ± 2 Ma suggesting the deposits belong to the Lower Cambrian Norretorp Member of the Læså Formation. The shallow marine deposits are strongly bioturbated, but only a single ichnoassociation is represented. The ichnogenus is referable to either Trichophycus Miller and Dyer, 1878 or Teichichnus Seilacher, 1955. Rare examples of Rusophycus Hall, 1852, probably trilobite trace fossils, are also represented.

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