scholarly journals Field Trip A (23 September 2018): geology and geomorphology of Giessen and its surrounding areas

2018 ◽  
Vol 1 ◽  
pp. 3-13
Author(s):  
Frank Volker ◽  
Stefanie Menges
Keyword(s):  
Volcanic Rocks ◽  
Volcanic Field ◽  
Field Trip ◽  
Tectonic Activity ◽  
Rheinisches Schiefergebirge ◽  
Variscan Orogeny ◽  
Upper Rhine Graben ◽  
Rhenish Massif ◽  
Surrounding Areas ◽  
North And South

Abstract. This field trip is intended to present an introduction to the geological and geomorphological evolution of Giessen and its surrounding areas (Fig. 1). The conference location of Giessen is located at the intersection of three major geological and morphological units: the Rheinisches Schiefergebirge (Rhenish Massif) to the west, the Hessische Senke (Hessian Depression) to the north and south and the Vogelsberg volcanic field to the east (Fig. 2). The rocks of the Rheinisches Schiefergebirge (Rhenish Massif) were formed during Paleozoic times, in the context of the Variscan orogeny. Dominant rock types include graywacke, slate, quartzite, and limestone, as well as mafic and felsic volcanics and their related pyroclastics. The area north and south of Giessen is dominated by the Hessische Senke (Hessian Depression), a north–south-trending subsidence area with several individual deposit segments. Due to Cenozoic tectonic activity, the Hessian Depression can be regarded as a connecting segment between the prominent Upper Rhine Graben and the smaller graben structures of northern Germany, and this is also documented by less consolidated Tertiary and Quaternary sediments. Long-lasting subsidence of the Hessian Depression, however, is indicated by the presence of Permian and Mesozoic sedimentary rocks. Rotliegend rocks are present towards the southwest rim of the Vogelsberg volcanic field and the Hanau-Seligenstädter Senke. Minor occurrences of Zechstein rocks are exposed along the Lahn valley between Giessen and Marburg. Mesozoic strata are dominated by Buntsandstein and are widespread in the Marburg area, with Muschelkalk and Keuper rocks being restricted to small erosional remnants in tectonic graben structures. The area to the east of Giessen is dominated by the Miocene Vogelsberg volcanic field, where an estimated area of 2500 km2 is covered by volcanic rocks of varying thickness, the Vogelsberg thus being the largest volcanic field of central Europe. The field trip provides an introduction to the geology, earth history and geomorphological characteristics of Giessen and its surrounding areas. We will therefore encounter rocks that formed in distinct geodynamic environments and within a timespan of roughly 400 Ma (Devonian to present).

scholarly journals Outline of the Nagssugtoqidian mobile belt of East Greenland

1979 ◽  
Vol 89 ◽  
pp. 9-18
Author(s):  
D Bridgwater ◽  
J.S Myers
Keyword(s):  
Shear Zones ◽  
Granulite Facies ◽  
Tectonic Activity ◽  
Mobile Belt ◽  
East Greenland ◽  
The North ◽  
Marginal Areas ◽  
High Level ◽  
North And South ◽  
Wide Zone

The Nagssugtoqidian mobile belt is a 240 km wide zone of deformation and plutonic activity which cuts across the Archaean craton of East Greenland. The belt was established 2600 m.y. ago by the formation of vertical E-W shear zones and the syntectonic intrusion of basic dykes. Tectonic activity along the E-W shear zones was followed by the emplacement of tonalitic intrusions, the Blokken gneisses, 2350 m.y. ago in the central parts of the mobile belt. The emplacement of the Blokken gneisses was accompanied and followed by further emplacement of basic dykes. These are synplutonic in the centre of the mobile belt but are emplaced into more rigid crust in the marginal areas of the belt and in the Archaean craton to the north and south. During a second major tectonic and thermal episode circa 1900 m.y. ago, the region was deformed by thrusting from the north. In the southem part of the mobile belt the earlier steep shear zones are cut by shear zones dipping gently northwards in which rocks are downgraded to greenschist facies. The grade of metamorphism increases northwards and shear zones are replaced by open folds with axial surfaces which dip gently northwards. The increasing ductility in the centre of and northem part of the belt is associated with the intrusion of charnockitic plutons and their granulite facies aureoles. Regional uplift occurred before the intrusion of high level post-tectonic plutons of diorite and granite 1550 m.y. ago.

Eruptive frequency of the Bora-Baricha-Tullu Moye (BBTM) volcanic system in the Central Main Ethiopian Rift

2021 ◽  
Author(s):  
Amdemichael Zafu Tadesse ◽  
Karen Fontijn ◽  
Abate Assen Melaku ◽  
Ermias Filfilu Gebru ◽  
Victoria Smith ◽  
...  
Keyword(s):  
Late Quaternary ◽  
Volcanic Eruptions ◽  
Volcanic Field ◽  
Tectonic Activity ◽  
Explosive Eruptions ◽  
Ethiopian Rift ◽  
Rift System ◽  
Diagnostic Features ◽  
Volcanic System ◽  
Main Ethiopian Rift

<p>The Main Ethiopian Rift (MER) is the northern portion of the East African Rift System and separates the Eastern and Western plateaus of Ethiopia. The recent volcanic and tectonic activity is largely focused within the rift basin along a 20 km wide zone on the rift floor. Large silicic volcanic complexes are aligned along this central rift axis but their eruptive histories are not well constrained.</p><p>The Bora-Baricha-Tullu Moye (BBTM) volcanic field is situated in the central Main Ethiopian Rift and has a different appearance than the other MER volcanic systems. The BBTM constitutes several late Quaternary edifices, the major ones are: Tullu Moye, Bora and Baricha. In addition, there are multiple smaller eruptive vents (e.g. Oda and Dima), cones, and domes across the ca. 20 X 20 km wide area. Currently, there is very little information on the frequency and magnitude of past volcanic eruptions. We present a new dataset of field observations, componentry, petrography, geochronology (<sup>40</sup>Ar/<sup>39</sup>Ar), and glass major and trace element chemistry. The data are assessed as potential fingerprints to assign diagnostic features and correlate units across the area, and establish a tephrostratigraphic framework for the BBTM volcanic field.</p><p>Two large-volume and presumably caldera-forming eruptions are identified, the younger of which took place at 100 ka. The volcanic products exposed in the BBTM area show that the volcanic field has undergone at least 20 explosive eruptions since then. The post-caldera eruptions have comenditic (Tullu Moye) and pantelleretic (Bora and Baricha) magma compositions. Other smaller edifices such as Oda and Dima also erupted pantelleritic magmas, and only differ slightly in composition than tephra of Bora and Baricha. Tullu Moye had two distinct explosive eruptions that dispersed tephra up to 14 km away and on to the eastern plateau. Bora and Baricha together had at least 8 explosive eruptions. Their deposits can be distinguished by their light grey color and unique lithic components. Oda had 7 eruptions, the most recent of which generated a pyroclastic density current that travelled up to 10 km away from the vent. Dima experienced at least 3 eruptions, generating tephra with a bluish-grey colour.</p><p>This mapping and compositional analysis of the deposits from the BBTM in the MER indicates that the region has been more active in the last 100 ka than previously thought, which has implications for hazards assessments for the region.</p>

scholarly journals The Impact of Complex Volcanic Plumbing on the Nature of Seismicity in the Developing Magmatic Natron Rift, Tanzania

2021 ◽  
Vol 8 ◽  
Author(s):  
Miriam Christina Reiss ◽  
James D. Muirhead ◽  
Amani S. Laizer ◽  
Frederik Link ◽  
Emmanuel O. Kazimoto ◽  
...  
Keyword(s):  
Volcanic Field ◽  
Tectonic Activity ◽  
Rift System ◽  
East African Rift System ◽  
Oldoinyo Lengai ◽  
Fault Plane Solutions ◽  
Magma Body ◽  
Volcanic Plumbing System ◽  
Stress Changes ◽  
The Impact

Constraining the architecture of complex 3D volcanic plumbing systems within active rifts, and their impact on rift processes, is critical for examining the interplay between faulting, magmatism and magmatic fluids in developing rift segments. The Natron basin of the East African Rift System provides an ideal location to study these processes, owing to its recent magmatic-tectonic activity and ongoing active carbonatite volcanism at Oldoinyo Lengai. Here, we report seismicity and fault plane solutions from a 10 month-long temporary seismic network spanning Oldoinyo Lengai, Naibor Soito volcanic field and Gelai volcano. We locate 6,827 earthquakes with ML −0.85 to 3.6, which are related to previous and ongoing magmatic and volcanic activity in the region, as well as regional tectonic extension. We observe seismicity down to ∼17 km depth north and south of Oldoinyo Lengai and shallow seismicity (3–10 km) beneath Gelai, including two swarms. The deepest seismicity (∼down to 20 km) occurs above a previously imaged magma body below Naibor Soito. These seismicity patterns reveal a detailed image of a complex volcanic plumbing system, supporting potential lateral and vertical connections between shallow- and deep-seated magmas, where fluid and melt transport to the surface is facilitated by intrusion of dikes and sills. Focal mechanisms vary spatially. T-axis trends reveal dominantly WNW-ESE extension near Gelai, while strike-slip mechanisms and a radial trend in P-axes are observed in the vicinity of Oldoinyo Lengai. These data support local variations in the state of stress, resulting from a combination of volcanic edifice loading and magma-driven stress changes imposed on a regional extensional stress field. Our results indicate that the southern Natron basin is a segmented rift system, in which fluids preferentially percolate vertically and laterally in a region where strain transfers from a border fault to a developing magmatic rift segment.

Neoproterozoic arc volcanic rocks of the Nanping-Ninghua tectonic belt, South China: Implications for the collision between the North and South Wuyi blocks

2018 ◽  
Vol 54 (4) ◽  
pp. 2679-2692 ◽  
Author(s):  
Yang Jiang ◽  
Xilin Zhao ◽  
Yanjie Zhang ◽  
Guangfu Xing ◽  
Mincheng Xu ◽  
...  
Keyword(s):  
South China ◽  
Volcanic Rocks ◽  
The North ◽  
Tectonic Belt ◽  
North And South

scholarly journals Urban Regeneration Projects Bound to Water, along and towards the Tagus Estuary (Portugal)

2019 ◽  
Vol 11 (23) ◽  
pp. 6578
Author(s):  
Caterina Anastasia
Keyword(s):  
Public Space ◽  
Urban Regeneration ◽  
Tagus Estuary ◽  
Open Spaces ◽  
The North ◽  
Surrounding Areas ◽  
The City ◽  
North And South ◽  
Hydrographic Network

Water is becoming a support for landscape and urban projects in a densely urbanised area settled along the Tagus Estuary, dubbed the City of the Tagus Estuary (CTE). Analysing two recent projects along and towards the Tagus Estuary hydrographic network, this article highlights how the most evident limit (the water) can function as the strongest binder, natural link, and shared public space of the CTE. Located, respectively, on the north and south banks of the estuary, the analysed projects become a way to think about urban strategies and promotions that use water as a way to build (re-build or reformulate) the image of the Lisbon Metropolitan Area. Today, open spaces bound to waterlines support an appealing and winning urban regeneration formula. Our goal is to understand what kind of role water is called to play with regard to the CTE. We ask: is the water called to play merely the role of building a new image of the city as a ground for investors? Is water the way to build a green and habitable CTE? This article concludes that the analysed projects contribute (as expected) to the promotion of the surrounding areas and propose appropriate solutions while occasionally overcoming the current local urban planning.

scholarly journals Trace-Element and Pb Isotope Evidence on Extracting Sulfides from Potassic Melts beneath Longmenshan and Molabushan Volcanoes, Wudalianchi, Northeast China

Minerals ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 319 ◽  
Author(s):  
Sergei Rasskazov ◽  
Yi-Min Sun ◽  
Irina Chuvashova ◽  
Tatyana Yasnygina ◽  
Chen Yang ◽  
...  
Keyword(s):  
Trace Element ◽  
Volcanic Rocks ◽  
Volcanic Field ◽  
Lava Flows ◽  
Pb Isotope ◽  
Linear Pattern ◽  
Wide Range ◽  
Mantle Sources ◽  
Isotope Evidence ◽  
Isotope Study

In the Wudalianchi volcanic field, eruptions started with low-Mg potassic lava flows 2.5–2.0 Ma ago and later changed to both low- and moderate-Mg potassic compositions. Volcanic rocks from the Molabushan and Longmenshan volcanoes record an unusually wide range of Pb abundances (from 3.7 ppm to 21 ppm relative to predominant range of 10–15 ppm). To determine the cause of these, we performed a comparative trace-element and Pb isotope study of rocks from these volcanoes and older lava flows. On a uranogenic lead diagram, older low-Mg lavas from lithospheric mantle sources plot on a secondary isochron with a slope corresponding to an age of 1.88 Ga. This contrasts with moderate-Mg volcanic rocks from the Molabushan cone, interpreted to have been derived from a recent convective mantle source, which define a flat linear pattern. Low-Mg rocks from the Molabushan flow have lead isotopic compositions that indicate mixed Gelaqiu and Molabu sources. Relative to rocks from the Molabushan cone, moderate-Mg lavas and slags from the East Longmenshan volcano have modified compositions characterized by Pb, S, and Ni abundances, Ni/Co, Ni/MgO ratios as well as 206Pb/204Pb, 207Pb/204Pb, 208Pb/204Pb, Ce/Pb, Th/Pb, and U/Pb ratios. We infer that the older Wudalianchi magmas were likely derived from a Paleoproterozoic lithospheric fragment, related to the evolved primordial mantle, and that later magmas were generated in the convecting mantle. These were influenced by segregation of small amounts of sulfides.

Apatite fission-track thermochronology of the Western Pontides (NW Turkey)

2011 ◽  
Vol 149 (1) ◽  
pp. 133-140 ◽  
Author(s):  
WILLIAM CAVAZZA ◽  
ILARIA FEDERICI ◽  
ARAL I. OKAY ◽  
MASSIMILIANO ZATTIN
Keyword(s):  
Fission Track ◽  
Late Eocene ◽  
Tectonic Activity ◽  
Late Oligocene ◽  
Apatite Fission Track ◽  
Tectonic Events ◽  
Fission Track Thermochronology ◽  
Nw Turkey ◽  
Tectonic Contact ◽  
North And South

AbstractThe results of apatite fission-track analyses of the Western Pontides of NW Turkey point to three discrete episodes of Cenozoic exhumation correlatable with major supraregional tectonic events. (1) Paleocene–early Eocene exhumation reflected the closure of the İzmir–Ankara ocean. (2) Late Eocene–earliest Oligocene exhumation was the result of renewed tectonic activity along the İzmir–Ankara suture. (3) Late Oligocene–early Miocene exhumation recorded the onset of northern Aegean extension. Samples collected north and south of the tectonic contact between the two terranes forming the Western Pontides (i.e. İstanbul and Sakarya terranes) record the same cooling events, suggesting that such terranes were amalgamated in pre-Cenozoic times.

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