Helga de Wall

Helga de Wall
Friedrich-Alexander-University of Erlangen-Nürnberg | FAU · Department of Lithosphere Dynamics

Dr. rer nat

About

136
Publications
28,484
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1,581
Citations
Citations since 2016
29 Research Items
809 Citations
2016201720182019202020212022020406080100120140
2016201720182019202020212022020406080100120140
2016201720182019202020212022020406080100120140
2016201720182019202020212022020406080100120140
Additional affiliations
October 2008 - present
Friedrich-Alexander-University of Erlangen-Nürnberg
Position
  • Professor (Full)
February 2002 - October 2008
University of Wuerzburg
Position
  • Professor

Publications

Publications (136)
Chapter
Sediments of the Aravalli Supergroup have acquired a complex superposed fold pattern during Neoproterozoic amalgamation (Grenvillian Orogeny) of north Indian blocks (Marwar block, Bundelkhand craton, North Delhi crustal block) and collision with the Central Indian Craton. The Upper Aravalli metasediments reveal a prograde mono-metamorphic history w...
Article
Erinpura Granites form the basement for the Neoproterozoic Malani Igneous Suite in NW India. Based on this study, the Erinpura granites can be divided into Erinpura-East (gneissic fabric), a belt parallel to the southern sector of the South Delhi Fold Belt, and Erinpura-West (magmatic fabrics). EPMA dating on monazites gives a time frame of 890 to...
Article
Full-text available
The origin and evolution of granites remain a matter of debate and several approaches have been made to distinguish between different granite types. Overall, granite classification schemes based on element concentrations and ratios, tectonic settings or the source rocks (I-, A-, S-type) are widely used, but so far, no systematic large-scale study o...
Article
Here we introduce a new model for a Tonian active continental margin in the Neoproterozoic western foreland of the Delhi Fold Belt of NW India. This study gives indication for a transition from continental crust into an active arc setting prior to emplacement of the volcano-plutonic Malani Igneous Suite. Erinpura Granites (890 to 860 Ma) are expose...
Article
Full-text available
The exposed Variscan basement in central Europe is well-known for its complex structural and lithological architecture resulting from multiple deformation phases. We studied the southwestern margin of the Bohemian Massif, which is characterized by major and long-lived shear zones, such as the Pfahl and Danube shear zones, extending over > 100 km an...
Preprint
Full-text available
The exposed Variscan basement in Central Europe is well-known for its complex structural and lithological architecture resulting from multiple deformation phases. We study the southwestern margin of the Bohemian Massif, which is characterized by major and long-lived shear zones, such as the Pfahl and Danube shear zones, extending over > 100 km and...
Article
Full-text available
Magnetic field maps display distinct anomalies for NE Bavaria. In this study we test several rock types, such as volcanic intercalations in paleozoic rock units, metamorphic rocks of the Münchberg Massif and granites of the Fichtelgebirge for their possible contribution to the magnetic anomalies. In some of the volcanic rocks (diabase, pillow lavas...
Chapter
Sediments of the Aravalli Supergroup have acquired a complex super-posed fold pattern during Neoproterozoic amalgamation (Grenvillian Orogeny) of north Indian blocks (Marwar block, Bundelkhand craton, North Delhi crustal block) and collision with the Central Indian Craton. The Upper Aravalli metasediments reveal a prograde mono-metamorphic history...
Article
The Deccan flood basalts cover large parts of India and represent one of the largest volcanic provinces on Earth. We present geochemical and isotopic data on a magnetically defined stratigraphic section of lavas from the northern portion of the Deccan, the Malwa Plateau, which are dated at ∼67.5 Ma. These are therefore some of the oldest Deccan lav...
Article
In NW India, large volumes of exposed Neoproterozoic basement rocks are formed by two magmatic suites, Erinpura granites as a late thermal event with respect to the \({\sim }\)1 Ga Delhi Orogeny and the younger Malani igneous suite (770–750 Ma). Average uranium and thorium equivalent concentrations (in ppm) inferred from spectroscopic gamma radiati...
Article
The Franconian Basin in NE Bavaria is a region of gravity low between the Bohemian Massif in the east and the Kraichgau Terrane in the west. Borehole measurements have identified the northern part of the Franconian Basin as a regional geothermal anomaly and new heat flow calculations give values of > 100 mW/m². Distinct negative Bouguer anomalies o...
Article
Full-text available
Fault systems are zones of crustal weakness and are used as pathways for ascending hydrothermal fluids. One impressive example is the more than 150 km long Bavarian Pfahl system at the SW boundary of the Bohemian Massif. Dextral ductile shearing of Moldanubian basement has shaped a several hundred meter wide zone of mylonites and ultramylonites. Th...
Poster
Full-text available
The SW border zone of the Bohemian Massif is well known for hosting some of the largest fault zones existing in Central Europe (Fig. 1). Complex tectonic reactivation processes are reflected by large variations in surface topography. High-resolution DEMs thereby reveal the presence of distinct morphotectonic domains. By comparing their spatial arra...
Article
Full-text available
Differenzierung von Graniten in der Oberpfalz (Nordost-Bayern) anhand von aerogeophysikalischen und in situ-gammaspektrometrischen Messungen Distinction of granites in the Oberpfalz (Northeast Bavaria) using aerogeophysical and in situ gamma spectrometry
Article
The Neoproterozoic Malani Igneous Suite (MIS) in NW India, along with analogous magmatic rocks from the adjoining Nagarparkar region in SE Pakistan can be collectively classified as a Silicic-dominated Large Igneous Province (SLIP). This magmatic event includes bimodal (predominantly felsic) volcanism, granite emplacement and felsic and mafic dyke...
Article
Full-text available
The Neoproterozoic Sindreth Basin, NW India, and its surrounding area represent a half graben structure situated between the undeformed Malani Igneous Suite (MIS) in the west and a corridor of coeval Cryogenian ductile deformation, anatexis and granite intrusion in the east. The main lithologies observed in the basin are conglomerate, fanglomerate,...
Poster
Full-text available
Hohe geothermische Gradienten in Thermalwasserbohrungen der Region Oberfranken geben Hinweise auf eine geothermische Anomalie in Nordostbayern, es wurden Wärme- stromdichten von > 100 mW/m² bestimmt. Tiefreichende Störungssysteme können Wegsamkeiten für krustale Fluide darstellen und dabei lokale Anomalien der Wärme- stromdichte verursachen. Das Fr...
Poster
Full-text available
In the Franconian foreland of exposed Variscan crust in N Bavaria, a distinct gravity low of 46 mGal is indicated in the map of Bouguer anomalies of Germany. The anomaly is linked to granitic bodys in the saxothurinigan basement analogous to the Fichtelgebirge and Oberpfalz granites east of the Franconian Line. This study presents results from 3D g...
Poster
Full-text available
Granites cover about 30% of the area of the Variscan Basement in the area of the Fichtelgebirge and Oberpfalz in NE Bavaria. The granitic terrain is expected to continue in strike direction of the variscan units in the western foreland below the permomesozoic platform. Granites are heat producing bodies in the earth crust because of the radioactive...
Poster
Full-text available
Tiefreichende Störungszonen können mögliche Wegsamkeiten für konvektiven Wärmetransport sein. Dieser Beitrag soll Möglichkeiten aufzeigen, solche Strukturen zu modellieren und zu detektieren.
Poster
Full-text available
Granites in the basement are potential heat sources for geothermal energy. The granitic terrain of the Fichtelgebirge is expected to continue in strike direction of the variscan units in the western foreland below the permomesozoic platform. A negative gravity anomaly to the west of Bayreuth in the Franconian Basin indicates a density contrast in t...
Article
Exhumed faults within the tonalitic Adamello pluton (Southern Alps) were seismic at depth as indicated by the presence of pseudotachylytes (solidified friction-induced melts). During cooling of tonalite, early-formed joints were first exploited by localized ductile shear zones associated with deposition of quartz veins (at ~ 500 °C), and later by p...
Article
Granites constitute a major part of the Variscan basement exposed in N Bavaria. It can be assumed that this granitic terrain continues west of the Franconian Fault and forms the basement of the Permo-Mesozoic sedimentary platform (Franconian basin). This region bears a distinct geothermal anomaly and is currently evaluated for its geothermal potent...
Article
Mafic dykes intrude the composite Mt. Abu granite batholith as a minor and the last phase of magmatism. The dykes are sub-vertical, variable in width and visibly compact, however, features of alteration and shearing can be seen. The dykes occurring within the recently identified and described, Delwara Shear Zone (DWSZ), from the western margin of t...
Article
Full-text available
Increased industrialization has adversely affected various components of the environment including soil, which is the ultimate site of settling and accumulation of fly ash. Fine respirable size particles in the atmosphere are detrimental to human health and their ultimate accumulation in the soil leads to soil pollution. In this study, these partic...
Article
Full-text available
The Wyangala Granite is a foliated, porphyritic Silurian granite from the Palaeozoic Circum-Pacific type Eastern Lachlan Orogen (ELO) of Australia. It is a paramagnetic ilmenite-bearing, S/marginal I type two-mica- to mainly biotite-granite with different biotite contents and local chlorite alteration. Very highly strained quartz–epidote bands are...
Research
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Abstract for poster presentation on the DGG (German Society of Geophysics) conference in March 2015, about gamma spectrometry on granites in the Fichtelgebirge (Germany).
Poster
Full-text available
The combination of field observations and microfabric studies, especially quartz c-axes fabrics, symmetry of microstructure and distribution of misorientation axis of low angle boundaries lead to a progress in the understanding of the kinematics of this shear zone. The N S trending shear zone developed subsequently to the emplacement of the Balda g...
Article
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Natural gamma ray measurements using a portable device were performed at 157 sites in the area around Sirohi town and Sindreth village in Rajasthan (NW India). This region comprises sedimentary rocks, metasediments, granites and gneisses that bear characteristic GR dose values and U/Th ratios corresponding with their specific geological history. A-...
Article
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The coastal tract of the Prydz Bay region in the East Antarctica exposes Archean to Late Proterozoic magmatic and medium-to high grade (amphibolite – granulite facies) metamorphic rocks. The para-and ortho gneisses from the Bharati promontory (Grovness Peninsula) forming a part of the Larsemann Hills in the southern segment of Prydz Bay were invest...
Article
This study provides further evidence for a Cryogenian (∼ 770 - 760 Ma) deformation event in NW India, a region generally regarded tectonically stable during the Rodinia to Gondwana transition. This deformation is prominent in the Sirohi region (southwestern Rajasthan State), previously referred to as the ‘Sirohi Orogeny’, younger to and independent...
Article
Basaltic lava flows of Malwa plateau together with the Mandla area and the Toranmal section constitute the Northern Deccan Province in central western India. With the present outcrop area of 80,000 km2 the Malwa flows form an extensive but relatively thin sequence. We sampled Deccan basalts along two 100 km each N-S and E-W transects along the wes...
Article
The evaluation of flow direction in volcanic rocks is among the most important applications of magnetic fabrics studies. A statistically significant sample set of titanomagnetite-bearing lava flows from the Malwa Plateau, the northern part of the Deccan traps in India has been investigated for a possible interference of induced and natural remanent...
Article
Full-text available
Field investigations, microstructural observations, and magnetic fabric analyses revealed a polyphase, late Pan-African deformational evolution in the Um Sheqila-Um Had (595 Ma) composite pluton and in the Hammamat and Atalla areas of the Central Eastern Desert of Egypt in Ediacaran times. Major stages are early shortening (NNW-SSE), subsequent str...
Article
Full-text available
One of the most prominent applications of anisotropy of magnetic susceptibility (AMS) measurements is the evaluation of flow fabrics in basalts. Basalts often contain Fe–Ti oxides with variations in grain/domain size fractions due to their variable cooling history. The origin of AMS in such rock types is of complex nature. Crystal shape, magnetocry...
Article
Tectonic pseudotachylytes, i.e. quenched friction-induced silicate melts, record coseismic slip along faults. Bestmann et al. (2012) have shown that transient high temperature conditions related to frictional heating during coseismic faulting in the brittle crust promoted the dynamical recrystallization of quartz to ultrafine-grained (grain size 1-...
Article
One of the most prominent applications of anisotropy of magnetic susceptibility (AMS) measurements is the evaluation of flow fabrics in basalts. Basalts often contain Fe-Ti oxides with variations in grain/domain size fractions due to their variable cooling history. The origin of AMS in such rock types is of complex nature. Crystal shape, magneto-cr...
Article
Full-text available
The Archean–Proterozoic contact (APC) comprises a large scale folded surface around Udaipur in NW India. The APC is exposed on both eastern and western flanks of a synclinorium formed during thick skinned thrusting of the Archean basement and the Paleoproterozoic cover units. Paleosol occurrences on both the limbs of this structure imply an origina...
Article
The Mt. Abu batholith in NW India comprises variably deformed porphyritic, granophyric to medium-grained granites and granite gneisses. They are intruded by rhyolitic and mafic dykes; the latter also mark the terminal magmatic phase in this batholith. Granitoids and rhyolitic dykes form a coherent group; petrographic and geochemical characteristics...
Article
Tectonic pseudotachylytes, i.e. quenched friction-induced silicate melts, record coseismic slip along faults and are mainly reported from the brittle crust in association with cataclasites. In this study, we document the occurrence of recrystallization of quartz to ultrafine-grained (grain size 1-2 μm) aggregates along microshear zones (50-150 μm t...
Article
Full-text available
Northern Ethiopia is marked by a fanning system of thrust planes with NW-dipping structures in the east and southeast-dipping in the west. The central zone of this large-scale (200 km long) structure is formed by a c. 10 km wide zone of localized strain and amphibolites facies metamorphic conditions (680 °C and 3.4 kbar) referred to as the Central...
Article
Full-text available
A small isolated mafic body occurs to the south of Sirohi near village Daba within the Neoproterozoic Erinpura Granite in the southern sector of the Proterozoic Delhi Fold Belt in NW India. This mafic body occurs close to a 100m wide NE–SW trending shear zone (Daba Shear Zone) which overprints the felsic rock fabrics. Further south, a small mafic b...
Article
Full-text available
The in-situ “chemical” Th–U–Pb dating of monazite with the electron microprobe is used to unravel the Neoproterozoic tectono-thermal history of the “Erinpura Granite” terrane in the foreland of the Delhi Fold Belt (DFB) in the NW Indian craton. These granitoids are variably deformed and show effects of shearing activity. Monazites from the Erinpura...
Article
Thin (0.5–2 mm thick) pseudotachylyte veins occur within muscovite-bearing (∼10% volume), amphibolite-facies quartzites of the Schneeberg Normal Fault Zone (Austroalpine, Southern Tyrol, Italy). Pseudotachylytes are associated with precursor localized plastic microshear zones (50–150 μm thick) developed sub-parallel to the host-rock foliation and w...
Data
Full-text available
und Helga de Wall 2 mit 3 Abbildungen Diesen Beitrag möchten wir Herrn Prof. H. Tobschall, Erlangen, widmen, der als Gründungsvorsitzender des Träger -und Fördervereins GEO-Zentrum an der KTBe.V. wesentlich zum Erfolg der Einrichtung beigetragen hat. Zusammenfassung Die Tiefbohrung in Windischeschenbach in der Oberpfalz ist ein Meilenstein in der G...
Conference Paper
Full-text available
As a result to human activities, the surface horizon of soils more or less associated with anthropogenic and/or industrial particles of the atmospheric dust precipitation in the term of pollutants. The concentration of these particulates positively correlated with the respiratory dieses. Here, we report the physical and chemical characteristic, the...
Article
Tube-like schlieren structures occur at the boundary between two units of the Fürstenstein Intrusive Complex, the Tittling and the Saldenburg granites. We have analysed the magnetic fabrics, petrographic variation and geochemistry of key examples of these structures in order to test the hypothesis that they originated as granitic microdiapirs. The...
Article
Full-text available
Geochronology using the in-situ "chemical" Th-U-Pb dating of monazite with the electron microprobe is used to unravel the Neoproterozoic tectonothermal history of the "Erinpura" granitoid terrane in the foreland of the Delhi Fold Belt in the NW Indian craton. These granitoids were partially deformed during shearing activity. Monazites from the Erin...
Article
Tectonic pseudotachylytes (pst), solidified friction-induced silicate melts, record coseismic slip and are mainly reported from the brittle crust and in association with cataclastic deformation. In this study, we report the close spatial association between crystal-plastic deformation of quartz, recorded by ultrafine-grained (grain size 1-2 µm) mic...
Article
Full-text available
The Mirpur granite body represents a relatively small (10 km2) pluton intruded along the northern margin of the adjacent Mt. Abu batholith (~125 km2) in NW India. It is a visibly undeformed alkali feldspar rich pink granite; in contrast, the Mt. Abu is a composite granitoid body and variably deformed. Both are intruded by rhyolitic dykes and the te...
Conference Paper
Sedimentologische und stratigraphische Analysen von Bohrkernen und Aufschlüssen aus der Bodenwöhrer Senke Nordost-Bayerns liefern Hinweise für terrestrische bis flach marine Ablagerungsbedingungen an der Südküste der Mitteleuropäischen Insel während des Turon. Die Sedimente wurden, begründet auf besondere lithologische und fazielle Merkmale, in der...
Article
Full-text available
A number of fine-grained sericite bearing pelitic, schistose lithologies occur along the Archean (Banded Gneiss Complex)-Proterozoic (Aravalli Supergroup) contact (APC) in the Udaipur valley in NW Indian craton. These Al-rich lithologies (subsequently metamorphosed) have been described as ‘paleosols’, developed over a 3.3 Ga old Archean gneissic ba...
Article
New PT data for the ca. 800 Ma old Pan-African Chila and Rama plutons are provided. By utilizing the AI-in-hornblende barometer pressures from 4.5 kbar for the Chila pluton and from 2.7 kbar for the Rama pluton were calculated. Crystallisation temperatures of hornblende were derived from the amphibole-plagioclasethermometer. Calculatedtemperatures...
Article
Full-text available
NW India is one of the key regions for plate tectonic reconstructionsof the I Ga to 750 Ma Rodinia accretion/breakupand the formation of East Gondwana. Within this frame, the Neoproterozoic« 900 Ma) magmatic and tectonic activity along the western flank of the Delhi Fold Belt is controversiallydebated. The Erinpura granite gneisses are deformed at...
Article
Full-text available
:The Early Silurian Wyangala Granite passively intruded already deformed Ordovician greywackes and volcaniclastics and was later deformed in the late Early Devonian and Early Carboniferous. The deformed Wyangala Granite contains discontinuous, north-south oriented high strain shear zones along its eastern margin which were defined using the prevale...
Article
Localised fault zones (0.5-2 mm) were analysed within a quartzitic host rock (with 5-10 vol% muscovite) of the "SchneebergZug" from the AustroalpineUnit (Southern Tyrol, Italy). They typically occur in fault and injectionvein association. Flow fabrics, spherulitic/microlitic and corrosion microstructures indicate the presence of a high temperature...
Article
:Emplacement of the Mashhad pluton in NE Iran is related to magmatic evolution at a convergent margin during closure of the Paleotethys. The pluton is formed by individual batches with S-type and I-type characteristics. Magnetic susceptibility is strongly variable but can be discriminatedinto three types (low:
Article
Full-text available
In the Hauzenberger pluton of East Bavaria two granites, (Hauz I and II) and a granodiorite are distinguished. Their magnetic susceptibility, measured in the field using a portable susceptometer, is low, but clear differences appear between the granodiorite (84 × 10−6 SI) and both granite types (52 × 10−6 SI). These differences are related to the v...
Article
Full-text available
Neoproterozoic acid magmatism in NW India has been described to represent a transition from late-tectonic Erinpura granitoids to the non-orogenic Malani Igneous Suite (MIS). The Erinpura granitoids, occurring in the Mt. Abu - Sirohi region, are variably deformed; the relatively undeformed 'pink granite' phase being regarded as correlative with the...