jurassic sequence
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2021 ◽  
Vol 247 ◽  
pp. 103858
Author(s):  
Paula Alexandra Gonçalves ◽  
Andreia Morgado ◽  
João Graciano Mendonça Filho ◽  
Joalice Oliveira Mendonça ◽  
Deolinda Flores


2020 ◽  
Vol 18 ◽  
pp. 1-14
Author(s):  
M.F. Pereira ◽  
C. Gama ◽  
J.B. Silva ◽  
Í. Dias da Silva

The dyke of the Papôa volcanic breccia cross-cutting the Lower Jurassic sequence of the Lusitanian Basin (West Iberia) contains granitic xenoliths. In this study, for the first time, U-Th-Pb zircon analysis of two xenoliths yielded 298±4Ma for biotite granite and of 292±2Ma for two-mica granite, indicating that the pre-Mesozoic basement of the Lusitanian Basin includes Permian intrusions. These ages are close within the margin of error of the age of the Late Carboniferous granites of the Berlengas isle that with the Late Devonian high-grade metamorphic rocks of the Farilhões isles, located northwest of the study area, which form the pre-Mesozoic basement of the Lusitanian Basin. These new geochronological findings enable it to be established that Permo-Carboniferous magmatism lasted at least 13Ma, in this region of the Appalachian-Variscan belt. Furthermore, a comparison with available data from Paleozoic tectonic units of the Appalachian-Variscan belt located both in the Iberian Massif and outside it enables the suggestion to be made that the Lusitanian Basin (Peniche) most probably rests on the South Portuguese Zone, which may also be correlated with the Rhenohercynian Zone present in southwest England, and the Meguma terrane of Nova Scotia.



2020 ◽  
Vol 56 (1) ◽  
pp. 187
Author(s):  
Rzger Abdula ◽  
Kamal Kolo ◽  
Maria-Elli Damoulianou ◽  
Victoria Raftopoulou ◽  
Polla Khanaqa ◽  
...  

The aim of this study is to assess the type, thermal maturity and the petroleum generation potential of the Upper Jurassic Naokelekan Formation, occurring across the Kurdistan Region of Iraq, by applying organic petrographical methods and Rock-Eval analysis. The Rock-Eval data would indicate the presence of kerogen types III, IV and II as the main constituents. However, the qualitative petrographical evaluation revealed that the main organic constituents are solid hydrocarbons, in the form of microgranular migrabitumens, with minor amounts of pyrobitumens. These secondary particles have affected the results of the Rock-Eval analysis and would have led to misinterpretation of organic matter typification based on pyrolysis results only. The combined results of petrography and pyrolysis indicate an active petroleum system within the Upper Jurassic sequence, where hydrocarbons are generated and reservoired within suitable lithologies.



2019 ◽  
Vol 27 (6) ◽  
pp. 29-40
Author(s):  
A. P. Ippolitov ◽  
D. B. Gulyaev

In the present paper we describe and discuss belemnite finds from the basal part of the middle Jurassic sequence at the southwest of the Republic of Tatarstan (Tetyushi district). The belemnites were collected from the outcrops located along a shoreline of the Kuybyshevskoye reservoir (Volga river) between the place Tarkhanovskaya pristan and the former village Dolinovka. These belemnites indicate that the basal part of the Jurassic sequence is Early Bathonian (Ishmae Zone) or, less probable, Middle Bathonian in age. Such dating triggers a critical review for the age of the middle Jurassic sequence in the region. In particular, poorly preserved ammonites previously collected from the same outcrops higher in the succession and interpreted as members of the Late Bajocian subfamily Garantianinae, are in fact Late Bathonian Gowericeratinae. Consequently, Beds with Garantiana nominally the most ancient ammonite-based biostratigraphic unit within the whole Jurassic of European Russia, based on this assemblage, is invalid.



2019 ◽  
Author(s):  
E. Voronovicheva ◽  
D. Litvichenko ◽  
D. Medvedev ◽  
Y. Pavlovsky ◽  
M. Tarakanovskii ◽  
...  


2019 ◽  
Vol 118 ◽  
pp. 01010
Author(s):  
Tai Xu ◽  
Shuang Li ◽  
Fengfeng Yang ◽  
Jufeng Zhang ◽  
Xiulan Zhu

Stratigraphic sequence contrast and sequence stratigraphic framework are of great significance for the sedimentary phase and sedimentary systems of coal-accumulating basin. In the coal-bearing basin, the variation of the flooding surface controls the migration law of the coal-concentrating centres within the range. Therefore, the sequence comparison work is crucial to find favorable coal-collecting areas. In addition, studying the position of the coal seam in the sequence stratigraphic framework and carrying out the sequence comparison work in the lateral direction can effectively track the change of the position of the coal seam in the sequence stratum and summarize the law of coal seam accumulation and occurrence, which can be better to plan and guide the exploration and development of coal resources in Longdong coalfield.



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