Prominent thermal anomalies in the mantle transition zone beneath the Transantarctic Mountains

Geology ◽  
2020 ◽  
Vol 48 (7) ◽  
pp. 748-752
Author(s):  
Erica L. Emry ◽  
Andrew A. Nyblade ◽  
Alan Horton ◽  
Samantha E. Hansen ◽  
Jordi Julià ◽  
...  
Keyword(s):  
Transition Zone ◽  
Upper Mantle ◽  
Lower Mantle ◽  
Low Velocity ◽  
Mantle Transition Zone ◽  
Thermal Anomalies ◽  
Victoria Land ◽  
Convective Thermal ◽  
Mantle Processes ◽  
Transantarctic Mountains

Abstract The Transantarctic Mountains (TAMs), Antarctica, exhibit anomalous uplift and volcanism and have been associated with regions of thermally perturbed upper mantle that may or may not be connected to lower mantle processes. To determine if the anomalous upper mantle beneath the TAMs connects to the lower mantle, we interrogate the mantle transition zone (MTZ) structure under the TAMs and adjacent parts of East Antarctica using 12,500+ detections of P-to-S conversions from the 410 and 660 km discontinuities. Our results show distinct zones of thinner-than-global-average MTZ (∼205–225 km, ∼10%–18% thinner) beneath the central TAMs and southern Victoria Land, revealing throughgoing convective thermal anomalies (i.e., mantle plumes) that connect prominent upper and lower mantle low-velocity regions. This suggests that the thermally perturbed upper mantle beneath the TAMs and Ross Island may have a lower mantle origin, which could influence patterns of volcanism and TAMs uplift.

scholarly journals Supplemental Material: Prominent thermal anomalies in the mantle transition zone beneath the Transantarctic Mountains

2020 ◽  
Author(s):  
E.L. Emry
Keyword(s):  
Transition Zone ◽  
Mantle Transition Zone ◽  
Thermal Anomalies ◽  
Additional Information ◽  
Transantarctic Mountains

Additional information about methods and results (Appendices S1 and S2, Figures S1–S8, and Datasets S1 and S2)<br>

scholarly journals Teleseismic Tomography for Imaging the Upper Mantle Beneath Northeast China

2020 ◽  
Vol 10 (13) ◽  
pp. 4557
Author(s):  
Zhuo Jia ◽  
Gongbo Zhang
Keyword(s):  
Travel Time ◽  
Transition Zone ◽  
Upper Mantle ◽  
Northeast China ◽  
Time Data ◽  
Low Velocity ◽  
Mantle Transition Zone ◽  
Teleseismic Tomography ◽  
Travel Time Data ◽  
Velocity Anomalies

Tomographic imaging technology is a geophysical inversion method. According to the ray scanning, this method carries on the inversion calculation to the obtained information, and reconstructs the image of the parameter distribution rule of elastic wave and electromagnetic wave in the measured range, so as to delineate the structure of the geological body. In this paper, teleseismic tomography is applied by using seismic travel time data to constrain layered crustal structure where Fast Marching Methods (FMM) and the subspace method are considered as forward and inverse methods, respectively. Based on the travel time data picked up from seismic waveform data in the study region, the P-wave velocity structure beneath Northeast China down to 750 km is obtained. It can be seen that there are low-velocity anomalies penetrating the mantle transition zone under the Changbai volcano group, Jingpohu Volcano, and Arshan Volcano, and these low-velocity anomalies extend to the shallow part. In this paper, it is suggested that the Cenozoic volcanoes in Northeast China were heated by the heat source provided by the dehydration of the subducted Pacific plate and the upwelling of geothermal matter in the lower mantle. The low-velocity anomaly in the north Songliao basin does not penetrate the mantle transition zone, which may be related to mantle convection and basin delamination. According to the low-velocity anomalies widely distributed in the upper mantle and the low-velocity bodies passing through the mantle transition zone beneath the volcanoes, this study suggests that the Cenozoic volcanoes in Northeast China are kindred and have a common formation mechanism.

scholarly journals Seismic structure of the lithosphere and upper mantle beneath the ocean islands near mid-oceanic ridges

Solid Earth ◽  
2014 ◽  
Vol 5 (1) ◽  
pp. 327-337 ◽  
Author(s):  
C. Haldar ◽  
P. Kumar ◽  
M. Ravi Kumar
Keyword(s):  
Transition Zone ◽  
Upper Mantle ◽  
Hot Spot ◽  
Quality Data ◽  
Moho Depth ◽  
Seismic Structure ◽  
Low Velocity ◽  
Mantle Transition Zone ◽  
Lithospheric Thickness ◽  
Ocean Islands

Abstract. Deciphering the seismic character of the young lithosphere near mid-oceanic ridges (MORs) is a challenging endeavor. In this study, we determine the seismic structure of the oceanic plate near the MORs using the P-to-S conversions isolated from quality data recorded at five broadband seismological stations situated on ocean islands in their vicinity. Estimates of the crustal and lithospheric thickness values from waveform inversion of the P-receiver function stacks at individual stations reveal that the Moho depth varies between ~ 10 ± 1 km and ~ 20 ± 1 km with the depths of the lithosphere–asthenosphere boundary (LAB) varying between ~ 40 ± 4 and ~ 65 ± 7 km. We found evidence for an additional low-velocity layer below the expected LAB depths at stations on Ascension, São Jorge and Easter islands. The layer probably relates to the presence of a hot spot corresponding to a magma chamber. Further, thinning of the upper mantle transition zone suggests a hotter mantle transition zone due to the possible presence of plumes in the mantle beneath the stations.

scholarly journals Supplemental Material: Prominent thermal anomalies in the mantle transition zone beneath the Transantarctic Mountains

2020 ◽  
Author(s):  
E.L. Emry
Keyword(s):  
Transition Zone ◽  
Mantle Transition Zone ◽  
Thermal Anomalies ◽  
Additional Information ◽  
Transantarctic Mountains

Additional information about methods and results (Appendices S1 and S2, Figures S1–S8, and Datasets S1 and S2)<br>

scholarly journals Supplemental Material: Prominent thermal anomalies in the mantle transition zone beneath the Transantarctic Mountains

2020 ◽  
Author(s):  
E.L. Emry
Keyword(s):  
Transition Zone ◽  
Mantle Transition Zone ◽  
Thermal Anomalies ◽  
Additional Information ◽  
Transantarctic Mountains

Additional information about methods and results (Appendices S1 and S2, Figures S1–S8, and Datasets S1 and S2)<br>

scholarly journals Features of the velocity structure of the mantle under the Precambrian structures on the example of the Indian platform (according to seismic tomography)

2021 ◽  
Vol 43 (1) ◽  
pp. 211-226
Author(s):  
L.N. Zaiets ◽  
I.V. Bugaienko ◽  
T.A. Tsvetkova
Keyword(s):  
Transition Zone ◽  
Seismic Tomography ◽  
Upper Mantle ◽  
Lower Mantle ◽  
Velocity Structure ◽  
Initial Approximation ◽  
Low Velocity ◽  
Tectonic Zone ◽  
Lower Velocity ◽  
Northern Border

The paper presents additional data, approaching to understanding the driving forces in the formation of geological structures and the development of the Indian platform. The results of seismic tomography are attracted here and their analysis is presented. A 3-dimensional P-velocity model of the mantle of the Indian platform was obtained according to the Taylor approximation method developed by V. Geyko. The undeniable advantages of the method are independence from the initial approximation (reference model) and the best approximation of nonlinearity. According to the data, the mantle under the Indian platform is influenced by both plumes and fluid systems. The influence of plumes is observed in the form of low-velocity subvertical exits from the lower mantle to the transition zone; fluids — in the form of interbedding of high and low velocity anomalies from the lower mantle (or from the transition zone of the upper mantle) to the upper mantle. An analysis is presented of both general velocity structure of the platform mantle and the velocity structure of the mantle under individual cratons (Bandelkand, Singhbum, Bastar and Darvar), the totality of which forms the Indian platform and the trap provinces. At lower velocity, an area is distinguished in the mantle that corresponds to the surface of the Narmada-Son lineament moving into the Central Indian Tectonic Zone. The mantle high-velocity structures under the Deccan trap province, together with their spreading area in the transitional zone of the mantle, subdivide the platform into two parts at depths of 375 km. Areas in the mantle with inclined layers were identified and analyzed: under the cratons Bandelkand and Singbum, the Rajmahal traps and the northern border of the Deccan traps. According to the model, an area bordering the Himalayas is well distinguished in the mantle. It is shown how, when the Indian platform collides with the Eurasian margin, the upper mantle stratifies into plates capable of independent motions, including subduction.

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