scholarly journals The Permian gypsum karst belt along the southern margin of the Harz-mountains (Germany), tectonic control of regional geology and karst hydrogeology

2020 ◽  
Vol 49 (1) ◽  
Author(s):  
Hans-Peter Hubrich ◽  
Stephan Kempe
Keyword(s):  
Lower Triassic ◽  
Karst Area ◽  
Upper Permian ◽  
Dense Matrix ◽  
The South ◽  
Harz Mountains ◽  
Tectonic Model ◽  
Northern Border ◽  
Karstic Features ◽  
Below Ground

The Harz Mountains in Germany are a south-tilting block of variscan-folded Devonian and Carboniferous rocks thrust over Mesozoic sediment along its northern border. Along the South Harz the overlying, unfolded upper-most Carboniferous, Permian and Buntsandstein (lower Triassic) series are exposed in a wide belt. They include a thick series of Upper Permian (“Zechstein”) evaporitic rocks, dipping with about 10° S to SW, representing a nearly continuous sulfate and carbonate karst area about 90 km long, covering 338 km². In his dissertation, the first author compiled a new geological map for the Zechstein at a scale of 1:10,000 and deduced a tectonic model to advance our understanding of the karstic features. Karstification determines the morphology of the South Harz including over 180 registered caves, thousands of sinkholes, uvalas, sinking creeks and large karstic springs. Specifically, lines of sinkholes appear to follow faults. By detailed mapping of the three lowermost Zechstein cycles, a dense matrix of faults is revealed. 85° to 125° striking faults reoccur every few 500 m, formed during the Harz-lifting compressional phase during the Upper Cretaceous. Many of these faults are reverse with a Nward thrust. This leads to repetitive exposure of the strata, causing the broadening of the Zechstein outcrop beyond what would be caused by the dip of the series alone. In other areas, horstand graben-structures are present, resulting in kilometer-long Lower Buntsandstein ridges. Below ground, the groundwater flowing southward along the dip is diverted into the direction of diachronicalthe strike, thus causing strike-parallel depressions, valleys and sinkhole rows. In the final extension phase, faults striking 150° to 180° have caused graben-structures, allowing groundwater and surface rivers to flow southward, breaking through the escarpment of the overlying Lower Buntsandstein. Therefore, the tectonic structure of the South Harz determines its hydrology and the karst features apparent at the surface. The tectonic situation of the three largest karstic springs, the Salza Spring at Förste, the Rhume Spring, and the Salza Spring at Nordhausen is discussed along with more shallow karstic settings of the Hainholz/Beierstein, the Trogstein and the area of Hainrode.

THE GEOLOGICAL EVOLUTION OF THE SOUTHERN TAROOM TROUGH AND THE OVERLYING SURAT BASIN

1974 ◽  
Vol 14 (1) ◽  
pp. 50 ◽  
Author(s):  
N. F. Exon
Keyword(s):  
Late Jurassic ◽  
Lower Triassic ◽  
Stream Sediments ◽  
Lower Jurassic ◽  
Late Triassic ◽  
Upper Permian ◽  
Lower Permian ◽  
Early Triassic ◽  
The South ◽  
The North

Isopach, structure contour, and palaeo-geological maps illustrate the geological development of the southern Taroom Trough and the lower part of the Surat Basin sequence.The meridional southern Taroom Trough, 50,000 km2 in area, is a southerly subsurface extension of the outcropping Bowen Basin. It is fault-bounded to the east and plunges northward. The maximum thickness of sedimentary fill increases northward from less than 400 m to 10,000 m, and consists of Lower Permian marine sediments, Upper Permian coal measures, Lower Triassic redbeds, and Middle Triassic stream sediments. The trough's present western margin is depositional, but the faulted eastern margin started to form in the Late Permian in the south and in the Early Triassic in the north; movement ceased in the Early Triassic in the south and in the Late Triassic in the north. Tectonic movements did not recur until Late Jurassic time.Late Triassic erosion preceded deposition of Surat Basin sediments. These sediments extended over ever wider areas, even the basal sands spreading far beyond the Taroom Trough. The fully-developed Surat Basin is 300,000 km2 in area, and contains up to 2500 m of dominantly continental Jurassic sediments and dominantly marine Lower Cretaceous sediments. Lower Jurassic stream sediments (the main petroleum producers of the basin) are thickest and coarsest above the Taroom Trough, suggesting steady subsidence and compaction of the trough sediments.By the Late Jurassic this compaction had virtually ceased, and epeirogenic uplift had given the basin its present shape, with the Mimosa Syncline (above the Taroom Trough) and the south-westerly-trending Dirranbandi Syncline (above a basement depression) being major structural features.Petroleum, which is probably derived from both Permian and Jurassic sources, is most abundant in the Lower Jurassic sandstone on either side of the Mimosa Syncline. Some aspects of the migration and trapping of Permian petroleum are discussed, and it is suggested that the Lower Jurassic Hutton Sandstone in the virtually unexplored Bollon area could be prospective.

Stratigraphic correlation of the Permian-Triassic red beds constrained by detrital zircon geochronology: Moscow basin, East European platform

2021 ◽  
Author(s):  
Alvina Chistyakova ◽  
Roman Veselovskiy
Keyword(s):  
Detrital Zircon ◽  
East European Platform ◽  
Lower Triassic ◽  
Detrital Zircons ◽  
Upper Permian ◽  
Stratigraphic Correlation ◽  
Red Beds ◽  
East European ◽  
Moscow Basin ◽  
Stratigraphic Position

<p>There's no doubt that nowadays detrital zircon U-Pb geochronology is actually required method of sedimentary basins analysis. Furthermore, this approach may have a lot of applications, such as a stratigraphic correlation. Here we present the first results of U–Pb LA–ICP–MS dating of detrital zircon from the Permian-Triassic red beds located within the Moscow Basin of the East European platform. Two outcrops have been studied: the Zhukov Ravine P/T boundary reference section and the Nedubrovo strata with uncertain stratigraphic position (uppermost Permian or lower Triassic?).</p><p>U–Pb ages of detrital zircon grains have been obtained for two samples – the Upper Permian and Lower Triassic age, which were taken in the proximity to the Permian–Triassic boundary in the Zhukov Ravine. Corresponding age distributions show contrasting provenance of the studied sedimentary rocks, pointing out that principal change in source of clastic material occurred on the Paleozoic-Mesozoic boundary. It means that detrital zircon U–Pb geochronology can be used as an additional independent tool for stratigraphic correlation of the Permian-Triassic red beds, at least within the Moscow Basin. We demonstrate this in the case of the Nedubrovo section with debated (Permian or Triassic?) stratigraphic position: the obtained data on detrital zircons persuasively suggests Early Triassic age of the Nedubrovo strata.</p><p>This study is supported by the Russian Foundation for Basic Research (project no. 18-05-00593).</p>

Focal mechanisms of earthquakes related to the 29 November 1975 Kalapana, Hawaii, earthquake: The effect of structure models

1981 ◽  
Vol 71 (3) ◽  
pp. 713-729 ◽  
Author(s):  
R. S. Crosson ◽  
E. T. Endo
Keyword(s):  
Main Shock ◽  
Horizontal Layer ◽  
Focal Mechanisms ◽  
Local Network ◽  
The South ◽  
Low Velocity ◽  
Tectonic Model ◽  
Low Velocity Layer ◽  
Using Data ◽  
Velocity Layer

abstract Initial focal mechanism determinations for the 29 November 1975 Kalapana, Hawaii, earthquake indicated discrepancy between the mechanism determined from teleseismic data by Ando and the mechanism determined using data from the local U.S. Geological Survey network surrounding the epicenter region. The resolution of this difference is crucial to correctly understand this earthquake, as well as to understand the tectonics of the south flank of Kilauea volcano. When a model with a low-velocity layer at the base of the crust is used for projection back to the focal sphere for the local network mechanisms, the discrepancy vanishes. To further investigate this result, focal mechanisms were determined using several contrasting models for a set of well-recorded earthquakes. A large number of these earthquakes have mechanisms identical to the main shock when the low-velocity layer model is used. Dispersion of P and T axes is also minimized by use of this model. A low-angle slip direction, favored for the main shock and typical of most other solutions, exhibits remarkable stability normal to the east rift zone of Kilauea. Our results suggest a tectonic model, similar in nature to that proposed by Ando, in which the south flank of Kilauea consists of a mobile block of crust which is relatively free to move laterally on a low-strength zone at about 10 km depth. Forceful injection of magma along the rift zones provides the loading stress which is released by catastrophic failure in the weak, horizontal layer in a cycle of perhaps 100 yr.

scholarly journals The first record of Upper Permian and Lower Triassic scorpions from Russia (Chelicerata: Scorpiones)

Euscorpius ◽  
2011 ◽  
Vol 2011 (121) ◽  
pp. 1-6
Author(s):  
Victor Fet ◽  
◽  
Dmitry E. Shcherbakov ◽  
Michael E. Soleglad ◽  
Keyword(s):  
Lower Triassic ◽  
First Record ◽  
Upper Permian

Quaternary chronology and rock uplift recorded by marine terraces, Gaviota coast, Santa Barbara County, California, USA

2021 ◽  
Author(s):  
Daniel L. Morel ◽  
Kristin D. Morell ◽  
Edward A. Keller ◽  
Tammy M. Rittenour
Keyword(s):  
Southern California ◽  
Seismic Hazard Assessment ◽  
Fault System ◽  
The South ◽  
Tectonic Model ◽  
Transverse Ranges ◽  
Marine Terraces ◽  
Uplift Rates ◽  
Regional Tectonic ◽  
Source Models

The Transverse Ranges of southern California are a region of active transpression on the western margin of North America that hosts some of the world’s highest uplift rates at the Ventura anticline. Yet, the manner in which rock uplift rates change along strike from Ventura to the westernmost Transverse Ranges and the structures that may be responsible for this uplift remain unclear. Here, we quantified rock uplift rates within the westernmost 60 km of the Transverse Ranges by obtaining new age constraints from raised beach and shoreface deposits from marine terraces along the Gaviota coast. Twelve radiocarbon (seven sites) and eight luminescence (six sites) ages, ranging from ca. 50 to 40 k.y. B.P. and ca. 56 to 43 ka, respectively, consistently suggest that the first emergent terrace dates to marine isotope stage (MIS) 3, rather than MIS 5a as previously reported for the western Gaviota coast. These younger ages yield rock uplift rates between 0.8 ± 0.3 and 1.8 ± 0.4 m/k.y., i.e., over five times higher than previous estimates for this region. The spatial distribution of rock uplift rates and the abrupt along-strike changes in marine terrace elevations favor a regional tectonic model with a step-wise change in rock uplift across the south branch of the Santa Ynez fault. The south branch of the Santa Ynez fault appears to separate two regional tectonic blocks, characterized by rock uplift rates of ∼1.3−1.6 m/k.y. to the east and slightly lower rates to the west (∼0.8−1.4 m/k.y.). Our observations suggest that coastal rock uplift is primarily accommodated by deeply rooted far-field structures such as the offshore Pitas Point−North Channel fault system and the Santa Ynez fault, and that smaller through-going structures impart second-order controls and locally accommodate short-wavelength (<10-km-long strike length) deformation. These results imply that although the rates of rock uplift decline westward along strike, the westernmost portion of the western Transverse Ranges nonetheless accommodates relatively high (>1 m/k.y.) rock uplift rates at a significant distance (>50 km) from the rapidly uplifting (6−7 m/k.y.) Ventura anticline, and >100 km from the prominent restraining bend (“Big Bend”) in the San Andreas fault. The new constraints on the geometry of Quaternary-active structures and regional rates of fault-related deformation have implications for regional earthquake source models and seismic hazard assessment in the highly populated southern California coast region.

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