scholarly journals Stress field changes in Central Europe from Late Miocene to Quaternary as determined from volcanic rocks in the Bohemian Massif

2020 ◽  
Author(s):  
Jakub Stemberk ◽  
Miroslav Coubal ◽  
Petra Štěpančíková
Keyword(s):  
Stress Field ◽  
Central Europe ◽  
Late Miocene ◽  
Bohemian Massif ◽  
Volcanic Rocks

scholarly journals Experimental evidence on the origin of Ca-rich carbonated melts formed by interaction between sedimentary limestones and mantle-derived ultrabasic magmas

Geology ◽  
2022 ◽  
Author(s):  
Michele Lustrino ◽  
Natascia Luciani ◽  
Vincenzo Stagno ◽  
Silvia Narzisi ◽  
Matteo Masotta ◽  
...  
Keyword(s):  
Experimental Study ◽  
Central Europe ◽  
Bohemian Massif ◽  
Potential Temperature ◽  
Volcanic Rocks ◽  
Maximum Amount ◽  
Primitive Character ◽  
Complete Dissolution ◽  
Massif Central ◽  
Limestone Assimilation

In this experimental study, we documented the formation of strongly ultrabasic and ultracalcic melts through the interaction of melilititic and basanitic melts with calcite. Three strongly to moderately SiO2-undersaturated volcanic rocks from the Bohemian Massif (central Europe) were mixed with 10, 30, and 50 wt% CaCO3 and melted at 1100, 1200, and 1300 °C at 2 kbar to evaluate the maximum amount of carbonate that can be assimilated by natural ultrabasic melts at shallow depths. Experiments revealed a surprisingly complete dissolution of the CaCO3, only rarely reaching carbonate saturation, with typical liquidus phases represented by olivine, spinel, melilite, and clinopyroxene. Only in the runs with the most SiO2-undersaturated compositions did abundant monticellite form instead of clinopyroxene. For all starting mixtures, strongly ultrabasic (SiO2 down to 15.6 wt%), lime-rich (CaO up to 43.6 wt%), ultracalcic (CaO/Al2O3 up to ~27) melt compositions were produced at 1200 and 1300 °C, with up to ~25 wt% dissolved CO2. When present, quenched olivine showed much higher forsterite content (Fo95–97) than olivine in the natural samples (Fo79–85). The two major results of this study are (1) silicate-carbonatite melt compositions do not necessarily imply the existence of carbonatitic components in the mantle, because they are also produced during limestone assimilation, and (2) Fo-rich olivines cannot be used to infer any primitive character of the melt nor high potential temperature (Tp).

Petrogenesis of Cenozoic high-Mg (picritic) volcanic rocks in the České středohoří Mts. (Bohemian Massif, Czech Republic)

2021 ◽  
Author(s):  
Lukáš Krmíček ◽  
Jaromír Ulrych ◽  
Emil Jelínek ◽  
Roman Skála ◽  
Simona Krmíčková ◽  
...  
Keyword(s):  
Czech Republic ◽  
Bohemian Massif ◽  
Volcanic Rocks

Two key switches in regional stress field during multi-stage deformation in the Carboniferous−Triassic southernmost Altaids (Beishan, NW China): Response to orocline-related roll-back processes

2021 ◽  
Author(s):  
Zhonghua Tian ◽  
Wenjiao Xiao ◽  
Brian F. Windley ◽  
Peng Huang ◽  
Ji’en Zhang ◽  
...  
Keyword(s):  
Stress Field ◽  
Large Scale ◽  
Electron Backscatter Diffraction ◽  
Volcanic Rocks ◽  
Structural Deformation ◽  
Regional Stress ◽  
Regional Stress Field ◽  
Multi Stage ◽  
Beishan Orogenic Collage ◽  
Roll Back

The orogenic architecture of the Altaids of Central Asia was created by multiple large-scale slab roll-back and oroclinal bending. However, no regional structural deformation related to roll-back processes has been described. In this paper, we report a structural study of the Beishan orogenic collage in the southernmost Altaids, which is located in the southern wing of the Tuva-Mongol Orocline. Our new field mapping and structural analysis integrated with an electron backscatter diffraction study, paleontology, U-Pb dating, 39Ar-40Ar dating, together with published isotopic ages enables us to construct a detailed deformation-time sequence: During D1 times many thrusts were propagated northwards. In D2 there was ductile sinistral shearing at 336−326 Ma. In D3 times there was top-to-W/WNW ductile thrusting at 303−289 Ma. Two phases of folding were defined as D4 and D5. Three stages of extensional events (E1−E3) separately occurred during D1−D5. Two switches of the regional stress field were identified in the Carboniferous to Early Permian (D1-E1-D2-D3-E2) and Late Permian to Early Triassic (D4-E3-D5). These two switches in the stress field were associated with formation of bimodal volcanic rocks, and an extensional interarc basin with deposition of Permian-Triassic sediments, which can be related to two stages of roll-back of the subduction zone on the Paleo-Asian oceanic margin. We demonstrate for the first time that two key stress field switches were responses to the formation of the Tuva-Mongol Orocline.

scholarly journals A new specimen of Araucaria fricii from the early Coniacian of the Bohemian Massif, Central Europe

2021 ◽  
Vol 77 (2) ◽  
pp. 282-286
Author(s):  
Jiří Kvaček
Keyword(s):  
Czech Republic ◽  
Central Europe ◽  
Bohemian Massif ◽  
Type Material ◽  
Massif Central ◽  
The Czech Republic ◽  
First Occurrence ◽  
Bohemian Cretaceous Basin ◽  
Cone Scale

A specimen of Araucaria fricii is described from the upper part of the Teplice Formation in the Bohemian Cretaceous Basin. It extends the first occurrence of A. fricii from the mid-Coniacian back to the early Coniacian. Found in the Radovesice locality near Kučlín in the northern part of the Czech Republic, it is characterised by a deltoid cone scale complex with a centrally placed seed. It is compared to the type material of A. fricii from the mid-Coniacian Březno Formation and other European Cretaceous species of Araucaria. The taphonomy and palaeoecology of A. fricii is briefly discussed.

Revision of the endemic dinoflagellate cyst genus Pontiadinium Stover & Evitt, 1978 from Lake Pannon and the Paratethys realm (Late Miocene–Early Pliocene, Central Europe)

Palynology ◽  
2021 ◽  
Author(s):  
Viktória Baranyi ◽  
Peta J. Mudie ◽  
Imre Magyar ◽  
Ádám Kovács ◽  
Mária Sütő-Szentai ◽  
...  
Keyword(s):  
Central Europe ◽  
Late Miocene ◽  
Lake Pannon ◽  
Early Pliocene ◽  
Dinoflagellate Cyst

Late Miocene mammals from Central Europe

1999 ◽  
pp. 165-190 ◽  
Author(s):  
Jens Lorenz Franzen ◽  
Gerhard Storch
Keyword(s):  
Central Europe ◽  
Late Miocene
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