Geoelectric deep sounding - a contribution to constraining the genesis of siliceous ferromanganese duricrusts on deeply weathered Palaeozoic basement rocks (N Bavaria, FR of Germany)

1987 ◽  
Vol 31 (3) ◽  
pp. 361-370
Author(s):  
H. Dill ◽  
H.-J. Ulrich
Keyword(s):  
Geophysics ◽  
2000 ◽  
Vol 65 (6) ◽  
pp. 1871-1881 ◽  
Author(s):  
Don White ◽  
David Boerner ◽  
Jianjun Wu ◽  
Steve Lucas ◽  
Eberhard Berrer ◽  
...  

Seismic reflection and electromagnetic (EM) data were acquired near Thompson, Manitoba, Canada, to map the subsurface extent of the Paleoproterozoic, nickel ore‐bearing Ospwagan Group. These data are supplemented by surface and borehole geology and by laboratory measurements of density, seismic velocity, and electrical conductivity, which indicate that Ospwagan Group rocks are generally more seismically reflective and electrically conductive than the Archean basement rocks that envelop them. The combined seismic/EM interpretation suggests that the Thompson Nappe (cored by Ospwagan Group rocks) lies blind beneath the Archean basement gneisses, to the east of the subvertical Burntwood lineament, in a series of late recumbent folds and/or southeast‐dipping reverse faults. The EM data require that the shallowest of these fold/fault structures occur within the basement gneisses or perhaps less conductive Ospwagan Group rocks. The results of this study demonstrate how seismic and deep sounding EM methods might be utilized as regional exploration tools in the Thompson nickel belt.


2020 ◽  
Vol 57 (3) ◽  
pp. 149-176
Author(s):  
Nur Uddin Md Khaled Chowdhury ◽  
Dustin E. Sweet

The greater Taos trough located in north-central New Mexico represents one of numerous late Paleozoic basins that formed during the Ancestral Rocky Mountains deformation event. The late Paleozoic stratigraphy and basin geometry of the eastern portion of the greater Taos trough, also called the Rainsville trough, is little known because the strata are all in the subsurface. Numerous wells drilled through the late Paleozoic strata provide a scope for investigating subsurface stratigraphy and basin-fill architecture of the Rainsville trough. Lithologic data obtained predominantly from petrophysical well logs combined with available biostratigraphic data from the greater Taos trough allows construction of a chronostratigraphic framework of the basin fill. Isopach- and structure-maps indicate that the sediment depocenter was just east of the El Oro-Rincon uplift and a westerly thickening wedge-shaped basin-fill geometry existed during the Pennsylvanian. These relationships imply that the thrust system on the east side of the Precambrian-cored El Oro-Rincon uplift was active during the Pennsylvanian and segmented the greater Taos trough into the eastern Rainsville trough and the western Taos trough. During the Permian, sediment depocenter(s) shifted more southerly and easterly and strata onlap Precambrian basement rocks of the Sierra Grande uplift to the east and Cimarron arch to the north of the Rainsville trough. Permian strata appear to demonstrate minimal influence by faults that were active during the Pennsylvanian and sediment accumulation occurred both in the basinal area as well as on previous positive-relief highlands. A general Permian decrease in eustatic sea level and cessation of local-fault-controlled subsidence indicates that regional subsidence must have affected the region in the early Permian.


2019 ◽  
Author(s):  
J. Wright Horton ◽  
◽  
David L. Daniels ◽  
Patrick D. Duff ◽  
Anjana K. Shah ◽  
...  
Keyword(s):  

Minerals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 604
Author(s):  
Evgeny V. Vetrov ◽  
Johan De Grave ◽  
Natalia I. Vetrova ◽  
Fedor I. Zhimulev ◽  
Simon Nachtergaele ◽  
...  

The West Siberian Basin (WSB) is one of the largest intracratonic Meso-Cenozoic basins in the world. Its evolution has been studied over the recent decades; however, some fundamental questions regarding the tectonic evolution of the WSB remain unresolved or unconfirmed by analytical data. A complete understanding of the evolution of the WSB during the Mesozoic and Cenozoic eras requires insights into the cooling history of the basement rocks as determined by low-temperature thermochronometry. We presented an apatite fission track (AFT) thermochronology study on the exposed parts of the WSB basement in order to distinguish tectonic activation episodes in an absolute timeframe. AFT dating of thirteen basement samples mainly yielded Cretaceous cooling ages and mean track lengths varied between 12.8 and 14.5 μm. Thermal history modeling based on the AFT data demonstrates several Mesozoic and Cenozoic intracontinental tectonic reactivation episodes affected the WSB basement. We interpreted the episodes of tectonic activity accompanied by the WSB basement exhumation as a far-field effect from tectonic processes acting on the southern and eastern boundaries of Eurasia during the Mesozoic–Cenozoic eras.


2013 ◽  
Vol 44 ◽  
pp. 113-125 ◽  
Author(s):  
Ryan Rabett ◽  
Lucy Farr ◽  
Evan Hill ◽  
Chris Hunt ◽  
Ross Lane ◽  
...  

AbstractThe paper reports on the sixth season of fieldwork of the Cyrenaican Prehistory Project (CPP) undertaken in September 2012. As in the spring 2012 season, work focussed on the Haua Fteah cave and on studies of materials excavated in previous seasons, with no fieldwork undertaken elsewhere in the Gebel Akhdar. An important discovery, in a sounding excavated below the base of McBurney's 1955 Deep Sounding (Trench S), is of a rockfall or roof collapse conceivably dating to the cold climatic regime of Marine Isotope Stage (MIS) 6 (globally dated to c. 190–130 ka) but more likely the result of a seismic event within MIS 5 (globally dated to c. 130–80 ka). The sediments and associated molluscan fauna in Trench S and in Trench D, a trench being cut down the side of the Deep Sounding, indicate that this part of the cave was at least seasonally waterlogged during the accumulation, probably during MIS 5, of the ~6.5 m of sediment cut through by the Deep Sounding. Evidence for human frequentation of the cave in this period is more or less visible depending on how close the trench area was to standing water as it fluctuated through time. Trench M, the trench being cut down the side of McBurney's Middle Trench, has now reached the depth of the latest Middle Stone Age or Middle Palaeolithic (Levalloiso-Mousterian) industries. The preliminary indications from its excavation are that the transition from the Levalloiso-Mousterian to the blade-based Upper Palaeolithic or Late Stone Age Dabban industry was complex and perhaps protracted, at a time when the climate was oscillating between warm-stage stable environmental conditions and colder and more arid environments. The estimated age of the sediments, c. 50–40 ka, places these oscillations within the earlier part of MIS 3 (globally dated to 60–24 ka), when global climates experienced rapid fluctuations as part of an overall trend to increasing aridity and cold.


Sign in / Sign up

Export Citation Format

Share Document