ODP/IODP 國際海洋鑽探研究計畫─子計畫七：台灣西南外海之地熱研究(Ⅱ)
Date Issued
2004
Date
2004
Author(s)
徐春田
DOI
922611M002011
Abstract
Thirtynine heat flow values off
Southwestern Taiwan on the accretionary
wedge were acquired by the heat probe
instrument which was developed by the
Institute of Oceanography, National Taiwan
University. The results show that the heat flow
values are 23~122.8 mW/m2 and the average is
61.04 mW/m2 which is approximately equal to
the heat flow of the normal sea floor. The heat
flows would be much higher than the present
values if the sedimentation effects were
considered. It indicates that the high heat flows
are induced from the compressional and
frictional processing during the formation of
the accretionary wedge. The heat flows or the
temperature gradients increase with the water
depth and reach to a maximum on the
continental rise. Due to considerably varied
temperature distribution beneath the ocean
floor, the bathymetric map and the heat flow
contours are inconsistent. BSRs are widely
distributed in the accretionary prism from the
toe region to steep slope. Assuming the density
of sediment is 1.7g/cm 3 , the base of gas
hydrate stability (BGHS) for each heat flow site
is calculated at the intersection between the
measured geotherm and the gas hydrate
boundary phase curve. The depths of BGHS at
measuring sites are shown in a figure and most
of them are around 200~400 mbsf. Heat flow
values increase with respect to the water depth
and do not affect the depth of BGHS. Contrary
to the common understanding that BGHS
generally increases with water depth, this
2
relation is not evident in the present case. The
maximum temperature of forming gas hydrate
is about 20℃. A further heat flow investigation
with a longer and better temperature calibration
probe is required to obtain a more accurate
prediction of BGHS.
Subjects
offshore southwestern Taiwan
heat flow
BGHS
Publisher
臺北市：國立臺灣大學海洋研究所
Type
report
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