Review for "Formation of Late Cretaceous high-Mg granitoid porphyry in central Lhasa, Tibet: Implications for crustal thickening prior to India-Asia collision"

2020 ◽  
Keyword(s):  
Late Cretaceous ◽  
Crustal Thickening

Late Cretaceous to Paleogene exhumation in Central Europe – localized inversion vs. large-scale domal uplift

2021 ◽  
Author(s):  
Hilmar von Eynatten ◽  
Jonas Kley ◽  
István Dunkl
Keyword(s):  
Central Europe ◽  
Late Cretaceous ◽  
Large Scale ◽  
Fission Track ◽  
Crustal Thickening ◽  
Dynamic Topography ◽  
Apatite Fission Track ◽  
Harz Mountains ◽  
Central Germany ◽  
Long Wavelength

<p>Large parts of Central Europe have experienced exhumation in Late Cretaceous to Paleogene time. Previous studies mainly focused on thrusted basement uplifts to unravel magnitude, processes and timing of exhumation. In this study we present a comprehensive thermochronological dataset from mostly Permo-Triassic strata exposed adjacent to and between the major basement uplifts in central Germany, comprising an area of at least some 250-300 km across. Results of apatite fission track and (U-Th)/He analyses from >100 new samples reveal that (i) km-scale exhumation affected the entire region, suggesting long-wavelength domal uplift, (ii) thrusting of basement blocks like the Harz Mountains and the Thuringian Forest focused in the Late Cretaceous (about 90-70 Ma) while superimposed domal uplift of central Germany appears slightly younger (about 75-55 Ma), and (iii) large parts of the domal uplift experienced removal of 3 to 4 km of Mesozoic strata. Using spatial extent, magnitude and timing as constraints we find that thrusting and crustal thickening alone can account for no more than half of the domal uplift. Most likely, dynamic topography caused by upwelling asthenosphere has contributed significantly to the observed pattern of exhumation in central Germany.</p>

Architecture of the crust and lithosphere beneath the Semail Ophiolite from ambient noise tomography and receiver functions: insights on the tectonic evolution of eastern Arabia

2021 ◽  
Author(s):  
Christian Weidle ◽  
Lars Wiesenberg ◽  
Andreas Scharf ◽  
Philippe Agard ◽  
Amr El-Sharkawy ◽  
...  
Keyword(s):  
Late Cretaceous ◽  
Ambient Noise ◽  
Function Analysis ◽  
Oceanic Lithosphere ◽  
Receiver Functions ◽  
Crustal Thickening ◽  
Ambient Noise Tomography ◽  
First Order ◽  
Pan African ◽  
Semail Ophiolite

<p>The Semail Ophiolite is the world<span>‘</span>s largest and best exposed oceanic lithosphere on land and a primary reference site for studies of creation of oceanic lithosphere, initiation of subduction, geodynamic models of obduction, subduction and exhumation of continental rocks during obduction. Five decades of geological mapping, structural, petrological and geochronological research provide a robust understanding of the geodynamic evolution of the shallow continental crust in northern Oman and how the late Cretaceous obduction process largely shaped the present-day landscape. Yet, prior to obduction, other first-order tectonic processes have left their imprint in the lithosphere, in particular the Neoproterozoic accretion of Arabia and Permian breakup of Pangea. Due to the scarcity of deep structure imaging below the ophiolite, the presence and significance of inherited structures for the obduction process remain unclear.</p><p>We discuss a new 3-D anisotropic shear wave velocity model of the crust below northern Oman derived from ambient noise tomography and Receiver Function analysis which allows to <span>resolve</span> some key unknowns in geodynamics of eastern Arabia: (1) <span>Several NE-trending structural boundaries in the middle and lower crust are attributed to the Pan-African orogeny and align with first-order lateral changes in surface geology and topography.</span> (2) The well-known Semail Gap Fault Zone is an upper crustal feature whereas two other deep crustal faults are newly identified. (3) Permian rifting occurred on both eastern and northern margins but large-scale mafic intrusions and/or underplating occurred only in the east. (4) While obduction is inherently lithospheric by nature, its effects <span>are mostly observed at shallow crustal depths, and lateral variations in its geometry and dynamics can be explained by effects on pre-existing Pan-African and Permian structures. (5) Continental subduction and exhumation during late Cretaceous obduction may be the cause for crustal thickening below today‘s topography.</span> (6) Thinning of the continental lithosphere below northern Oman in late Eocene times – possibly related to thermal effects of the incipient Afar mantle plume - provides a plausible mechanism for the broad emergence of the Oman Mountains and in particular the Jabal Akhdar Dome. Uplift might thus be unrelated to compressional tectonics during Arabia-Eurasia convergence as previously believed.</p>

scholarly journals Petrogenesis of Mesozoic, Peraluminous Granites in the Lamoille Canyon Area, Ruby Mountains, Nevada, USA

2003 ◽  
Vol 44 (4) ◽  
pp. 713-732 ◽  
Author(s):  
Sang-Yun Lee ◽  
Calvin G. Barnes ◽  
Arthur W. Snoke ◽  
Keith A. Howard ◽  
Carol D. Frost
Keyword(s):  
Great Basin ◽  
Late Cretaceous ◽  
Heat Input ◽  
Crustal Thickening ◽  
Dehydration Melting ◽  
Granitic Gneiss ◽  
Peraluminous Granites ◽  
Ruby Mountains ◽  
Sevier Orogeny ◽  
Biotite Dehydration Melting

Abstract Two groups of closely associated, peraluminous, two-mica granitic gneiss were identified in the area. The older, sparsely distributed unit is equigranular (EG) with initial εNd ∼ − 8·8 and initial 87Sr/86Sr ∼0·7098. Its age is uncertain. The younger unit is Late Cretaceous (∼80 Ma), pegmatitic, and sillimanite-bearing (KPG), with εNd from −15·8 to −17·3 and initial 87Sr/86Sr from 0·7157 to 0·7198. The concentrations of Fe, Mg, Na, Ca, Sr, V, Zr, Zn and Hf are higher, and K, Rb and Th are lower in the EG. Major- and trace-element models indicate that the KPG was derived by muscovite dehydration melting (<35 km depth) of Neoproterozoic metapelitic rocks that are widespread in the eastern Great Basin. The models are broadly consistent with anatexis of crust tectonically thickened during the Sevier orogeny; no mantle mass or heat contribution was necessary. As such, this unit represents one crustal end-member of regional Late Cretaceous peraluminous granites. The EG was produced by biotite dehydration melting at greater depths, with garnet stable in the residue. The source of the EG was probably Paleoproterozoic metagraywacke. Because EG magmatism probably pre-dated Late Cretaceous crustal thickening, it required heat input from the mantle or from mantle-derived magma.

scholarly journals Late Cretaceous to Paleogene exhumation in central Europe – localized inversion vs. large-scale domal uplift

Solid Earth ◽  
2021 ◽  
Vol 12 (4) ◽  
pp. 935-958
Author(s):  
Hilmar von Eynatten ◽  
Jonas Kley ◽  
István Dunkl ◽  
Veit-Enno Hoffmann ◽  
Annemarie Simon
Keyword(s):  
Central Europe ◽  
Late Cretaceous ◽  
Large Scale ◽  
Fission Track ◽  
Crustal Thickening ◽  
Dynamic Topography ◽  
Harz Mountains ◽  
Central Germany ◽  
First Time ◽  
Region Ii

Abstract. Large parts of central Europe experienced exhumation in Late Cretaceous to Paleogene time. Previous studies mainly focused on thrusted basement uplifts to unravel the magnitude, processes and timing of exhumation. This study provides, for the first time, a comprehensive thermochronological dataset from mostly Permo-Triassic strata exposed adjacent to and between the basement uplifts in central Germany, comprising an area of at least some 250–300 km across. Results of apatite fission-track and (U–Th) / He analyses on > 100 new samples reveal that (i) kilometre-scale exhumation affected the entire region, (ii) thrusting of basement blocks like the Harz Mountains and the Thuringian Forest focused in the Late Cretaceous (about 90–70 Ma), while superimposed domal uplift of central Germany is slightly younger (about 75–55 Ma), and (iii) large parts of the domal uplift experienced removal of 3 to 4 km of Mesozoic strata. Using spatial extent, magnitude and timing as constraints suggests that thrusting and crustal thickening alone can account for no more than half of the domal uplift. Most likely, dynamic topography caused by upwelling asthenosphere significantly contributed to the observed pattern of exhumation in central Germany.

Formation of Late Cretaceous high‐Mg granitoid porphyry in central Lhasa, Tibet: Implications for crustal thickening prior to India–Asia collision

2020 ◽  
Vol 55 (10) ◽  
pp. 6696-6717 ◽  
Author(s):  
Zuo‐Wen Dai ◽  
Han‐Xiao Huang ◽  
Guang‐Ming Li ◽  
Jan‐Marten Huizenga ◽  
M. Santosh ◽  
...  
Keyword(s):  
Late Cretaceous ◽  
Crustal Thickening

Nd and Sr isotopic constraints on the petrogenesis of the west side of the northern Coast Mountains batholith, Alaskan and Canadian Cordillera

1991 ◽  
Vol 28 (6) ◽  
pp. 939-946 ◽  
Author(s):  
Scott D. Samson ◽  
P. Jonathan Patchett ◽  
William C. McClelland ◽  
George E. Gehrels
Keyword(s):  
Late Cretaceous ◽  
Crustal Thickening ◽  
Northern Coast ◽  
Crustal Material ◽  
The West ◽  
Crustal Component ◽  
Coast Mountains ◽  
Early Proterozoic ◽  
Depleted Mantle ◽  
Wrangellia Terrane

Nd and Sr isotopic ratios are reported from 15 samples of plutons of the northern Coast Mountains batholith (CMB), between. the Alexander–Wrangellia terrane and the Stikine terrane of southeastern Alaska. Samples of plutons that are part of the Late Cretaceous – Eocene CMB suite have a range in initial εNd of −3.0 to −0.2 and 87Sr/86Sr of 0.70494–0.70607. There is no correlation of isotopic ratio with age, lithology, or geographic location of these plutons. Two plutons that are probably older than the bulk of the CMB plutons have present-day εNd values of −6.8 and −2.6.The Late Cretaceous – Eocene plutons have Nd depleted-mantle model ages (tDM) of 620–1070 Ma. These data indicate that the northern CMB must contain a significant component of old, evolved continental crust. The presence of an old crustal component is further demonstrated by inherited zircons of average Early Proterozoic age contained in some plutons. The mid to Late Proterozoic tDM ages of the CMB plutons are therefore a result of a mixture of Early Proterozoic crustal material with. younger, juvenile crust. The most likely source of this old crustal component is the Yukon–Tanana terrane, a fragment composed of ancient crustal material that occurs within and directly to the west of the northern CMB. The juvenile component is probably a combination of material derived from the mantle and from anatexis of the surrounding juvenile terranes. Crustal anatexis may have occurred as a result of the intrusion of mafic melts related to subduction along the outboard margin of the Alexander–Wrangellia terrane, by crustal thickening due to the underthrusting of the Alexander–Wrangellia terrane beneath the Yukon–Tanana and Stikine terranes, or by a combination of both processes.

The southern Omineca Belt, British Columbia: new perspectives from the Lithoprobe Geoscience Program

1995 ◽  
Vol 32 (10) ◽  
pp. 1720-1739 ◽  
Author(s):  
Sharon D. Carr
Keyword(s):  
Late Cretaceous ◽  
Seismic Reflection ◽  
Shear Zones ◽  
Crustal Thickening ◽  
Seismic Reflection Data ◽  
Reflection Data ◽  
Basement Rocks ◽  
Peraluminous Granites ◽  
Surface Geology ◽  
Lower Crustal

Geological, isotopic, and geochronology studies carried out by university and government researchers, concurrently with the Lithoprobe program, have greatly refined our understanding of the regional geology, crustal structure, and tectonics of the Omineca Belt. Sound correlations have been established between surface geology and seismic reflection data. Cretaceous–Eocene thrust faults that are imaged in the subsurface in the Shuswap complex may be part of a break-forward thrust system that feeds into the Purcell Anticlinorium and the Foreland Belt. The Monashee décollement is the western continuation of the sole thrust beneath the Foreland Belt and provides a means of linking shortening across the entire orogen. The thermal peak of metamorphism in the central and southern Shuswap complex is now known to have occurred in the Late Cretaceous–Paleogene in contrast with earlier held views. North American basement rocks are now known to extend beneath the eastern half of the Canadian Cordillera. Geochronology studies have revealed Early Proterozoic and Late Cretaceous–Eocene metamorphism in basement rocks of the Monashee complex, and suggest that these rocks were located to the east of the metamorphic front throughout the Jurassic and Early Cretaceous. Anatectic peraluminous granites were produced in the Shuswap complex between 135 and 52 Ma in response to pulses of crustal thickening and heating, and in some cases served to localize Eocene extensional shear zones and to transfer extensional displacement from one shear zone to another. A flat Moho and other seismic reflection data are consistent with interpretations of lower crustal flow to balance early Tertiary extension in the upper crust. Crustal-scale extension and the Slocan Lake fault zone provided the source and setting for Ag–Pb–Zn–Au mineralization in the Nelson–Silverton area.

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