Water Content in the Mantle Transition Zone Beneath the North Pacific Derived from the Electrical Conductivity Anomaly

2013 ◽  
pp. 171-179 ◽  
Author(s):  
Takao Koyama ◽  
Hisayoshi Shimizu ◽  
Hisashi Utada ◽  
Masahiro Ichiki ◽  
Eiji Ohtani ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Water Content ◽  
Transition Zone ◽  
North Pacific ◽  
Conductivity Anomaly ◽  
Mantle Transition Zone ◽  
The North ◽  
The North Pacific

Electrical conductivity in the mantle transition zone beneath Eastern China derived from L1-Norm C-responses

2020 ◽  
Vol 221 (2) ◽  
pp. 1110-1124 ◽  
Author(s):  
Yanhui Zhang ◽  
Aihua Weng ◽  
Shiwen Li ◽  
Yue Yang ◽  
Yu Tang ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Objective Function ◽  
Water Content ◽  
Transition Zone ◽  
Regularization Parameter ◽  
Eastern China ◽  
Bfgs Method ◽  
L1 Norm ◽  
Mantle Transition Zone ◽  
Dehydration Reactions

SUMMARY Constraining the distribution of water in different regions of the mantle remains one of the significant challenges to comprehend the global deep water cycle. Geomagnetic depth soundings can provide such constraint through the electrical conductivity structure. Hence, this study aims to propose a regularization technique that can estimate previously unavailable C-response. In the method, the objective function comprised an L1-norm measured data prediction error and a spectral smoothness constraint term. We used the data error of C-response to weight the predicted error. The L-BFGS method was introduced to determine the minimum point of the objective function, and the regularization parameter decreased adaptively during inversion. Thus, the geomagnetic data processed yielded high-quality C-responses in 31 stations in Eastern China. In addition, we obtained 1-D electrical conductivity profiles in the mantle transition zone (MTZ) beneath Eastern China from C-responses using the L-BFGS method. Compared with the global 1-D model, the conductivity–depth profiles revealed that the MTZ beneath Eastern China is more conductive in the east but more resistive in the west. The conversion of these conductivities to water content based on the mineral physics suggested that the MTZ beneath Eastern China is characterized by a high water concentration, approximately 0.2 and 1 wt per cent in the upper and lower MTZ, respectively. Owing to the inclusion of more stations, the water-rich region could be constrained roughly to the east of the North–South Gravity Lineament (NSGL). Further considering seismic images in the same area, this water content distribution pattern suggested that the front of the stagnant Pacific Plate in the lower MTZ might have reached the NSGL. However, the dehydration reactions in the stagnant slab were more active in the eastern part. Perhaps, some of these fluids migrated into the upper MTZ and could be the source of the trapped water found in the xenoliths from the deep upper mantle beneath Eastern China.

scholarly journals Revised 1-D mantle electrical conductivity structure beneath the north Pacific

2010 ◽  
Vol 180 (3) ◽  
pp. 1030-1048 ◽  
Author(s):  
Hisayoshi Shimizu ◽  
Takao Koyama ◽  
Kiyoshi Baba ◽  
Hisashi Utada
Keyword(s):  
Electrical Conductivity ◽  
North Pacific ◽  
The North ◽  
Conductivity Structure ◽  
The North Pacific

Mantle transition zone beneath a normal seafloor in the northwestern Pacific: Electrical conductivity, seismic thickness, and water content

2017 ◽  
Vol 462 ◽  
pp. 189-198 ◽  
Author(s):  
Tetsuo Matsuno ◽  
Daisuke Suetsugu ◽  
Kiyoshi Baba ◽  
Noriko Tada ◽  
Hisayoshi Shimizu ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Water Content ◽  
Transition Zone ◽  
Northwestern Pacific ◽  
Mantle Transition Zone

Habitats of two albatross species during the non-breeding season in the North Pacific Transition Zone

2015 ◽  
Vol 162 (4) ◽  
pp. 743-752 ◽  
Author(s):  
Bungo Nishizawa ◽  
Daisuke Ochi ◽  
Hiroshi Minami ◽  
Kotaro Yokawa ◽  
Sei-Ichi Saitoh ◽  
...  
Keyword(s):  
Transition Zone ◽  
Breeding Season ◽  
North Pacific ◽  
The North ◽  
The North Pacific

scholarly journals Summertime Tintinnid Community in the Surface Waters Across the North Pacific Transition Zone

2021 ◽  
Vol 12 ◽  
Author(s):  
Haibo Li ◽  
Jun Xuan ◽  
Chaofeng Wang ◽  
Zhaohui Chen ◽  
Gérald Grégori ◽  
...  
Keyword(s):  
Transition Zone ◽  
North Pacific ◽  
Warm Water ◽  
Type I ◽  
Water Type ◽  
The North ◽  
Important Region ◽  
Oceanic Species ◽  
The Common ◽  
The North Pacific

Located from 35° to 45° latitude in both hemispheres, the transition zone is an important region with respect to the planktonic biogeography of the sea. However, to the best of our knowledge, there have been no reports on the existence of a tintinnid community in the transition zone. In this research, tintinnids along two transects across the North Pacific Transition Zone (NPTZ) were investigated in summer 2016 and 2019. Eighty-three oceanic tintinnid species were identified, 41 of which were defined as common oceanic species. The common oceanic species were further divided into five groups: boreal, warm water type I, warm water type II, transition zone, and cosmopolitan species. Undella californiensis and Undella clevei were transition zone species. Other species, such as Amphorides minor, Dadayiella ganymedes, Dictyocysta mitra, Eutintinnus pacificus, Eutintinnus tubulosus, Protorhabdonella simplex, and Steenstrupiella steenstrupii, were the most abundant in the NPTZ but spread over a much larger distribution region. Species richness showed no obvious increase in the NPTZ. Boreal, transition zone, and warm water communities were divided along the two transects. Tintinnid transition zone community mainly distributed in regions with water temperatures between 15 and 20°C. The tintinnid lorica oral diameter size classes were dominated by the 24–28 μm size class in three communities, but the dominance decreased from 66.26% in the boreal community to 48.85% in the transition zone community and then to 22.72% in the warm water community. Our research confirmed the existence of tintinnid transition zone species and community. The abrupt disappearance of warm water type I species below 15°C suggested that this group could be used as an indicator of the northern boundary of the NPTZ.

scholarly journals Seasonal photoacclimation in the North Pacific Transition Zone

2021 ◽  
Author(s):  
Gregory L Britten ◽  
Christine Padalino ◽  
Gaël Forget ◽  
Michael J. Follows
Keyword(s):  
Transition Zone ◽  
North Pacific ◽  
The North ◽  
The North Pacific
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