TY - JOUR
T1 - Heat flow survey in the vicinity of the branches of the megasplay fault in the Nankai accretionary prism
AU - Yamano, Makoto
AU - Kawada, Yoshifumi
AU - Hamamoto, Hideki
N1 - Funding Information:
We are grateful to the officers, crews, and scientific parties of cruises KH-10-3 and KH-11-9 of the R/V Hakuho-maru for their assistance with the heat flow measurements. We also thank S. Goto for useful discussions and anonymous reviewers for valuable comments on the first version of the manuscript. This study was conducted as a part of the sub-project ‘Recent activity of seismogenic faults’ of the KANAME project (New perspective of great subduction-zone earthquakes from the super deep drilling) and supported by MEXT KAKENHI Grant Number 21107003.
Publisher Copyright:
© 2014 Yamano et al.; licensee Springer.
PY - 2014/12/1
Y1 - 2014/12/1
N2 - Heat flow measurements were conducted at four sites in the Nankai accretionary prism southeast of the Kii Peninsula, around the area where the megasplay fault reaches the surface, in conjunction with long-term monitoring of bottom water temperature at nearby stations. Analysis of the obtained data showed that variations in bottom water temperature seriously affect surface heat flow measurements in the areas with water depths of less than about 2,800 m. This effect can reach up to 20% to 30% and may have significantly contributed to a large scatter in the heat flow values previously measured in the study area. The temperature records were also used to determine heat flows from sediment temperature profiles disturbed by bottom water temperature variations. Results of measurements at sites deeper than 2,800 m indicate that the regional heat flow, corrected for surface disturbances including the influence of bathymetric relief, is about 65 mW/m2, which is consistent with the value calculated using subduction thermal models. Local high heat flow values were obtained in the vicinity of the tips of the branches of the splay fault, suggesting advective heat transport by upward pore fluid flow along the faults.
AB - Heat flow measurements were conducted at four sites in the Nankai accretionary prism southeast of the Kii Peninsula, around the area where the megasplay fault reaches the surface, in conjunction with long-term monitoring of bottom water temperature at nearby stations. Analysis of the obtained data showed that variations in bottom water temperature seriously affect surface heat flow measurements in the areas with water depths of less than about 2,800 m. This effect can reach up to 20% to 30% and may have significantly contributed to a large scatter in the heat flow values previously measured in the study area. The temperature records were also used to determine heat flows from sediment temperature profiles disturbed by bottom water temperature variations. Results of measurements at sites deeper than 2,800 m indicate that the regional heat flow, corrected for surface disturbances including the influence of bathymetric relief, is about 65 mW/m2, which is consistent with the value calculated using subduction thermal models. Local high heat flow values were obtained in the vicinity of the tips of the branches of the splay fault, suggesting advective heat transport by upward pore fluid flow along the faults.
KW - Accretionary prism
KW - Bottom water temperature
KW - Cold seep
KW - Heat flow
KW - Nankai Trough
KW - Pore fluid
KW - Splay fault
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U2 - 10.1186/1880-5981-66-126
DO - 10.1186/1880-5981-66-126
M3 - Article
AN - SCOPUS:84922617932
VL - 66
JO - Earth, Planets and Space
JF - Earth, Planets and Space
SN - 1343-8832
IS - 1
M1 - 126
ER -