Tibet matched die method

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                        Chang Chia-Chou
                        Gas Analysis of TCDP

                    R92224207 Chia-Chou Chang

Abstract A 2000m borehole will be drilled through the Chelungpu Fault
at Bighole, Taichung. In order to understand the influence of a fault on
gases, four jobs are planned to be done as follow. (1) Onsite continuous
monitoring: The changes of gases with depth could be detected by
continuous monitoring with a QMS. (2) Analysis of pore gases: The
chemical compositions and isotope ratios of gases derived from core
samples would be investigated. (3) Analysis of gases in rocks: The
gases trapped in the rock fragments would be discharged by thermal
diffusion and be analyzed. (4) Post-drilling gas monitoring and flux
measurement: With the long-term gas monitoring and flux
measurement, it is possible to correlate the monitoring data with the
records of fault activities.
                                       Chu Mei-Fei

Accessory minerals such as zircon and apatite occur widely in various rocks because of their wide stability
in geological processes, which allow these minerals to be used as an indicator for not only igneous
petrogenesis but also potentially for sedimentary source provenance. In this study, we report trace element
analyses of apatite separates from selected granitic rocks from southeastern Tibet using LA-ICP-MS,
composed of a New Wave LUV-213 Nd:YAG laser and an Agilent 7500s ICP-MS at NTU. Samples that we
analyzed include (1) undeformed I- and S-type granitoids from the Gangdese Batholith and
Nyainqentanglha magmatic belt, emplaced in the southern and northern parts of the Lhasa terrane,
respectively, (2) a granitic migmatite from Langxian, located in the southern margin of the Gangdese
Batholith, and (3) a granitic gneiss from Tongmai, in the Jiali shear zone. These apatites show remarkable
difference in their trace element compositions, best manifest by the contents of rare earth elements (REE).
Apatites from I-type granitoids (SiO2= 62~70 wt.%), the principal component of the Gangdese Batholith
characterized by positive eNd(T) isotopic compositions, exhibit apparent enrichments in the light REE
[LREE, e.g., (La/Yb)N=1.51~26.8; avg. =13.7±5.5 (1s, n=33)]. In contrast, apatites from S-type granitoids
(SiO2= 70~74 wt.%), which constitute the Nyainqentanglha belt and have negative eNd(T) values, show
generally flat REE patterns [(La/Yb)N=0.56~1.54; avg. =0.99±0.73 (n=36)]. Apatites from both types of the
granitoids, further marked by significant negative Eu anomalies [(Eu/Eu*)N=0.04~0.45] in the REE patterns,
can be distinguished from those from the metamorphosed rocks that show LREE-depleted patterns
[(La/Yb)N=0.02~1.30; avg.=0.15±0.25 (n=29)]. The latter shows mild Eu anomalies [(Eu/Eu*)N=0.13~0.80
and 0.21~0.53 for apatites of the Tongmai gneiss and Longxian migmatite, respectively]. This pilot study
indicates that REE chemistry of the apatites (1) correlates with compositions of the host magmas and thus
can be used as a probe into igneous petrogenesis, (2) changes between igneous and metamorphic
conditions, and (3) has higher potential than zircon to be used as a provenance indicator in particular when
combined with in-situ Sr isotope determinations of these apatites to be carried out.

(sentenses too long)
                                     Chiu Han- I
High precision determination of Mg/Ca and Sr/Ca ratios in marine carbonates using
     cool plasma quadrupole inductively coupled plasma mass spectrometry

A technique has been developed to simultaneously determine high precision Mg/Ca and
Sr/Ca ratios in marine carbonates using cool plasma quadrupole inductively coupled
plasma mass spectrometry (ICPMS). Trace elements of marine carbonates are natural
archives of global changes and paleoceanography, for example, Mg/Ca in foraminiferal
shells and Sr/Ca in coral skeletons are broadly used as proxies of temperature variation.
Reduced the temperature of plasma could eliminate general argon complexes associated
with normal plasma and can dramatically improve detection limits of many elements what
we interest. Couple with CETAC MCN6000 desolvation system and T1H microcentric
nebulizer can usefully enhance signal sensitivity and reduce sample size requirement. All
elements were determined in pulse-counting mode (including 24Mg, 43Ca, 48Ca, 86Sr).
Mg/Ca and Sr/Ca ratios were decided directly from intensity ratios using external standard,
matrix-matched standard to correct for instrumental mass discrimination. Matrix-induced
variations in mass discrimination are extremely sensitive with calcium concentration on
Mg/Ca ratios, especially at low calcium concentration (< 5 ppm). However, these effects
are insignificant if the calcium concentration of samples and standard are within 7-10 ppm.
This method of simultaneous determination of multi-ratios shows a good measurement
precision (2s) of Mg/Ca = 0.6 % and Sr/Ca = 0.4 % for small size marine carbonate
samples (<5 g). Furthermore, this small sample requirement is enough to investigate the
characteristic of single chamber of one foraminifer cell. This technique can efficiently
improve the performance of quadrupole ICPMS, obtain paleoceanographic interests in
marine carbonates and sufficiently reduce overall sample requirement.
                               Li Hsiao-fen
          The variations in components of fumaroles and bubbling gases of hot
springs are significantly related to volcanic activity. The Tatun Volcano Group is
nearby the Taipei main city. There will be a great disaster if the Tatun Volcano
Group reactivates. Although the Tatun Volcano Group is defined a dormant
volcano traditionally, the helium isotopic data implies that a magma chamber may
exist underneath the Tatun Volcano Group. It is important to monitor the Tatun
Volcano Group urgently. According to the prior analyses, most of the fumarolic
gas samples mainly contain stream water. The dry gases of the samples after
dehydration are dominated with CO2.
          New methods for sample collection and analytical procedures are
applied in the Tatun Volcano Group to analyse their gas compositions. It is tested
by 9 and 5 successive samples being collected at SYK (小油坑) on 29 July 2003
and 13 November 2003, respectively. The result shows that the methods are
suitable for volcanic gas study. The degassing system was quite steady in short
period (few hours). And the dry gas composition of fumaroles seems not to be
affected by environmental factors.
          Further, it is necessary to test the procedure and technique of iodine
analysis method to understand the relationship of H2S/SO2 ratio. Analyses of
condensed water (D and 18O) of fumarolic gases from the Tatun Volcano Group
to realize the sources of the water. Spatial and temporal variations of gas
compositions are necessary for better comprehension.
                                       Hsieh Pei-Shan
Apatite rare earth element abundances as a tool to recognize the granite petrogenesis: Applications
to Mesozoic granitic rocks in S China

The systematic and distinctive differences in rare earth element (REE) abundances, distribution patterns, and
ratios have been successfully used to discriminate source-different S-type granites and I-type granites of the
Lachlan Fold Belt in Australia. On this basis, REE abundances of apatites from typical S-type and I-type
granites of Cathaysia Block in S China are used to compare with Early Yanshanian granitic rocks from
Huashan, Kuidong, Jiufeng and Fogang batholiths using the method of LA-ICP-MS. Apatites from Indosinain
S-types (Darongshan) show convex-upward REE distribution patterns, with significant depletions of LREE
((La/Sm)N = 0.57-0.69, (La/Yb)N = 0.94-1.22) and Eu (Eu/Eu* = 0.01) and slight Nd anomaly. In contrast,
apatites from Late Yanshanian I-types (Zudi and Yanqian) are characterized by right-inclined REE distribution
patterns, with LREE enrichment ((La/Sm)N = 1.49-10.7, (La/Yb)N = 5.80-34.7), small Eu anomaly (Eu/Eu* =
0.12-0.40) but no Nd depletion. Besides, in apatites from S-types the most abundant element of the REE
group is Y, while in apatites from I-types the most abundant one is Ce. As a result, apatites from Huashan,
Kuidong and Jiufeng have right-inclined REE distribution patterns, LREE enrichment ((La/Sm)N = 0.97-1.44,
(La/Yb)N = 1.39-5.85), slight Eu anomaly (Eu/Eu* = 0.12-0.36) and no Nd depletion, whereas those from
Fogang have convex-upward REE distribution patterns ((La/Sm)N = 0.58-1.01, (La/Yb)N = 1.3-2.5), distinct
depletion of Eu (Eu/Eu* = 0.02-0.05) and no Nd depletion. When Sr and Nd isotopic compositions of these
batholiths are concerned, Early Yanshanian granitic rocks (ISr = 0.71121 to 0.72260 and eNd(T) = -9.2 to -12.2)
fall between the Indosinian S-types (ISr = 0.7219 to 0.7300 and eNd(T) = -9.4 to -12.1 ) and Late Yanshanian I-
types (ISr = 0.7045 to 0.7077 and eNd(T) = -4.8 to –5.6). All these observations suggest that Early Yanshanian
granitic rocks are intermediate between I-types and S-types, and granitic magmas of different stages
progressively evolved with mantle involvement. Furthermore, there is clear evidence of strong relationships
between granitoid types and geodynamic environments. Therefore, characteristic REE abundances,
distribution patterns, and ratios of apatites are able to identify different sources of granitic rocks in S China,
applied to granite petrogenesis and potentially used as geodynamic tracers.
Do you see
 10 faces?   Young lady & old witch
                                  Lan Te Fang

      Measurements of CO2 flux in the Tatun Volcano Group, Northern Taiwan

           The topic “Will Tatun Volcano Group (TVG) explode again??” has been deeply
concerned (has caused much concern), especially for people in Taipei. Several models
were proposed to explain whether TVG will continuously active or extinct. However,
according to tuffaceous dating, the former explosion was only about 0.2 Ma ago.
Moreover, data of micro-seismic network and He isotope also indicate the existence of
magma chamber underneath the TVG. Thus, a long-term monitor of the TVG is quite
           CO2 is, after water vapor, the most abundant gas phase dissolved into magma.
It„s also one of the first gases to be exsolved and released from ascending magma. Thus,
increase in volcanic CO2 emission can be used as early indicators of magma up-rising.
Even during repose periods of volcanic activity, volcanoes release high amounts of CO2.
Therefore, monitoring volcanoes with CO2 flux could keep us at safe distance from active
craters. In addition to monitoring volcanoes, mapping of CO2 emanation may help to
identify the active structural features of volcanic edifices, and even the position of magma
chamber. Combining CO2 flux with He and C isotopes will help us identify the source of
gas and estimate the total CO2 contribution of TVG. This method can be widely applied to
other area and more gas species.
                                      Liu Chia-Mei
                          Application of the Silica heat flow in South Taiwan

Surface heat flow data are important to constrain regional thermal regimes and play as a key to
unravel the thermal structure of tectonic evolution. The published data of heat flow in Taiwan are
poor in quality and spatial distributions (Lee and Cheng, 1986). However, several papers based on
those data have been published to quantitatively study the thermal structure and mountain-building
processes of Taiwan (Barr and Dahlen, 1989; Hwang and Wang, 1993; Lin, 2000; Song and Ma, 2002).
The result, thus, of course are not convincible. In this case (?), we need better quality and more heat
flow data to precisely study the thermal structure and orogenic evolution of Taiwan.

In this report, I will propose a method, i.e. the silica geothermometer, to estimate underground
thermal water equilibrium temperature as well as surface heat flow. The basic principle of the silica
geothermometer is utilizing the silica content of the thermal water in equilibrium with quartz in the
geothermal reservoir, when thermal water ascending to surface become equilibrium with amorphous
silica (Fournier and Rowe,1966). Three assumptions are required in this method: (1) water and rock
in equilibrium at depth; (2) neither silica precipitation, nor mixing surface water; and (3) and enough
silicate minerals in the rock of geothermal reservoir. Based on the linear relationship between silica
geothermometer and regional heat flows (Chandler et al., 1980), of northern American continent, the
regional surface heat flow map can be quickly drawn.

The silica geothermometer is a direct, convenient and cheaper method to quickly determine the
regional surface heat flow distributions. Furthermore, comparing with traditional borehole heat flow
measurement the quality and precision of it are reasonable and trustable. This method has been
applied to the south Taiwan to estimate the temperature of subsurface geothermal reservoir and
draw the silica heat flow distribution map. The result shows two anomalous areas in the east of the
Central Range, which is consistent with the results derived from the stable isotope, quartz and illite
crystallinity and non-seismic distribution.
                                        Tsai C. C.
High-Resolution Seismic Images and 3-D Seismic Velocities of the San Andreas Fault Zone at Burro
Flats, Southern California

                 C. C. Tsai12, R. D. Catchings1, M. J. Rymer1, and M. R. Goldman1
      U.S. Geological Survey, 345 Middlefield Rd. MS 977, Menlo Park, CA 94025 2Institute of
       Oceanography, National Taiwan University, P.O. Box 23-13, Taipei, Taiwan 106, Taiwan

The southern San Andreas fault (SAF) has produced large earthquakes in the past 1500 yrs. Burro Flats,
a basin within the San Bernardino Mountains, is bounded on the southwest by the southern San Andreas
fault. Burro Flats has been the site of paleoseismological investigations to determine the slip history of
the fault. Additional paleoseismic studies at this location are needed to further resolve the structure and
slip history of the SAF. In addition to the main trace of the SAF at Burro Flats, there are splay faults,
suggesting a complex geometry for the fault. To better understand the structure of the SAF, we acquired
a 3-D, combined seismic reflection/refraction profile centered on the main trace at Burro Flats. The
seismic investigation included a 60 m by 70 m rectangular array. Sensors were spaced every 5 m;
seismic sources, likewise with a spacing of 5 m, consisted of a combination of down-hole explosives
and shallow (approximately 0.3 m) Betsy Seisgun shots. Data were recorded without acquisition filters
for 5 s at a 0.5-ms sampling rate. To analyze the data for velocity structure, we used a tomographic
inversion procedure to invert first-arrival refractions. Preliminary measurements from shot gathers
show that near-surface velocities range between 700 m/s and 1500 m/s. We observe apparent travel-
time delays of approximately 7 ms near the main surface trace of the SAF, suggesting that seismic
imaging methods may be useful in identifying this and other fault traces. These results will be useful for
paleoseismic investigations. (very readable)
                                  Wen Da-jen
New SHRIMP U-Pb zircon data from the Gangdese batholith: implications for the
Transhimalayan magmatic evolution

The Gangdese batholith that crops out in the southern Lhasa terrane marks one of the main
products of the Transhimalayan magmatism caused by northward subduction of the Neo-Tethyan
slab before the India-Asia collision. Here we present new SHRIMP U-Pb zircon results for this
batholith, which are combined with published age data to delineate a magmatic duration from ~110
to 40Ma. Such a prolonged magmatic activity, however, appears to have clustered in two stages, in
the Cretaceous (~110-80 Ma) and Paleogene (~60-40 Ma), respectively, with a gap during ~80-60 Ma.
The age span of the former stage overlaps with that (~135-75 Ma) of the granitoids and associated
volcanic rocks emplaced in the Nyainqentanglha belt in the northern part of the Lhasa terrane. In
comparison with the Nyainqentanglha granitoids that are dominantly S-type and marked by
significant involvement of the continental crust in magma generation, the Cretaceous Gangdese
granitoids show geochemical affinities with adakites from modern subduction zones. The
Gangdese adakites (SiO2= 66-69%) are highly depleted in HREE and Y (<10 ppm), so coupled with
elevated La/Yb and Sr/Y, and do not display Eu anomalies. Their overall geochemical and isotopic
features are consistent with an origin by melting of a garnet-bearing source that is most likely to
be the partial melt of the tectonically thickened lower crust. These observations point to a flat
subduction that, as in the case of central Andes, can account for the heat required to melt the slab
and the widespread nature of the Cretaceous phase of the Transhimalayan magmatism in the
Lhasa terrane. In contrast, the younger phase of this arc magmatism was confined to the south,
represented by the Paleogene stage of the Gangdese plutons and contemporaneous Linzizong
volcanic successions. These magmas, ranging from mafic to felsic compositions typical of the
calc-alkaline nature, have Sr-Nd isotope ratios [e.g., eNd(T)= +3 to +5] suggesting a prevailing
contribution by a juvenile mantle component that we infer to have been caused by an
asthenospheric doming due to rollback of the Neo-Tethyan slab and its subsequent breakoff into
the deep mantle.
                               Fu Ching-Chou 1
       Recognition of buried fault and/or fracture by the soil gas method
         In this work, the soil-gas method is being used to compare geochemical
data with the geological and geomorphological Information, which can be obtained
rapidly and at a relatively low cost. Fractures are conduits may provide high
permeability pathways through bedrock, gases will migrate upward through open
fractures from crustal or mantle, producing anomalously high concentrations in the
soil above.
         Samples were collected at a spacing of 250~300 m, from a depth of
approximately 100 cm, using a hollow steel probe driven with a sledgehammer.
More than 222 soil-gas samples were collected along several traverses crossing the
observed structures and analyzed for 4He, CO2 etc.. Major gases were He and
CO2,each of them for their characteristic: 4He has a low and constant atmospheric
concentration (5.239 ± 0.004 ppm), whereas CO2 is the major soil gas component
with a mainly surficial biogenic source. However, there could additionally be CO2
from crustal or mantle degassing.Data analysis clearly reveals anomalous values
for each gas at specific positions along the traverses.
         Keeping as far as possible to similar soil and ground surface condition over
the area covered by the traverse also helps to minimize spurious reading or trends.
The correlation of linear soil gas anomalies with mapped fractures suggests that
where gas-bearing units underlie an area, soil gas analysis may provide a method
of mapping fault or/and fractures where exposure is too poor for conventional
                    Chu Chiou-Hong
The geochemical characteristics of Kueishantao volcanic rocks
          The Okinawa Trough, extending form SW Kyushu to NE Taiwan, is widely
regarded as an intracontinental backarc basin that is built behind the Ryukyu arc-
trench system owning to subduction of the Philippine Sea plate underneath the
Eurasian plate (too long). Kueishantao (= Turtle islet) is an emerged islet located at the
western end of the Southernmost Part of the Okinawa Trough (SPOT) volcanic field
that consists dominantly of andesitic lava flows. Kueishantao is located only ~100 km
above the Wadati-Benioff zone. All trace elements data were measured using an
Inductively Coupled Plasma Mass Spectrometry (ICP-MS). Kueishantao rocks plot in
the higher portion of the median-K field in the SiO2 vs. K2O diagram, similar to early
to middle Miocene volcanic rocks form the central Ryukyu arc, which were emplaced
before the Okinawa Trough opening. The incompatible element variation patterns of
Kueishantao volcanics are marked by relative enrichment in the large ion lithophile
elements (LILE; Cs, Rb and Ba) and Th, U and Pb, and deletion in the high field-
strength elements (HFSE; Nb, Ta and Ti), a feature typical of arc magmas from the
Ryukyu subduction zone as well as other convergent margins. The andesites from
Kueishantao have higher 87Sr / 86Sr (0.7058-0.7069) and lower 143Nd / 144Nd (0.5124-
0.5126) which are similar to the northern Ryukyu arc lavas. There are five samples of
Kueishantao volcanics have higher MgO contents and we suggest that they may be the
high-Mg andesite (HMA). We have to need more geochemical data to support
Kueishantao relating to the arc volcanoics.
                                   Li Zheng-Yi
           Biomisation is originated from Europe (Prentice et al., 1996). This is a useful software
allow us to research the past biome of plant (or vegetation). First, we must build two matrixes--
(pollen assemblageplant functional type) & (plant functional typebiome). And through the
two matrixes, the software could build directly the relationship between pollen assemblage and
biome. Second, we throw the pollen data into the software, and it will calculate the data with the
relationship. Finally, it will tell us what biome is the fittest.
           Last year, we have built the matrixes of Taiwan. Now we use the pollen data which is
from the core of Toushe Basin, Central Taiwan to perform the software, and see if the software
of Europe and our matrixes are suitable for the samples of Taiwan. According to the 300 pollen
data and the 29 radiocarbon data, a late Quaternary vegetation is presented from the Toushe
Basin. The vegetation record commences at around 100000 yr BP and shows that from this time
up until 96000 yr BP (stage 5a), warm climates prevailed in the Toushe Basin and subtropical
seasonal forest dominated. Expansion of temperature deciduous forest occurred during the
96000 ~ 9600 yr BP (stage 4, 3 & 2), indicating cold conditions. The warmer climates prevailed
again after this, but the vegetation is dominated by warm mixed forest during the Holocene(9600
~ 1840 yr BP), indicating the condition could be colder than 96000~100000 yr BP.
           The result is accord with the change of climate that we have known over the last
100000 years, so Biomisation is almost suitable for the samples of Taiwan. But there is also
some shortcoming. First, because of the disturbance of human, we have no natural pollen
assemblage which is from below 500 m a.s.l., so the tropical vegetation was not presented here.
And second, because of the disappearance of vegetation of LGM from Taiwan, we can not get
the analogue. So during 9600 ~ 96000 yr BP, there is a long record of temperature deciduous
forest, and we could be under the illusion that the climate was unchanged during this time.
                                      Li Kuei-Shu
My study evaluates the accuracy of U-Th dates for young corals (<one thousand years old), and
we expect to achieve an accuracy of better than 1 year for corals with an age <400 year. Tracers
in coralline have been widely used as environment proxies to reconstruct paleoclimatic condition.
However, we can interpret correctly environmental and paleoclimatic records according to
accuracy age control. Traditionally, the chronology in the coral was determined by dark-light
annual band counting and using fluorescence, but the preceding methods have age biases. For
instance, we have band counting problem when band is not distinct. Therefore, we propose to
apply our well-established ICP-MS analytical technique to develop a high precision absolute age
control method for young corals. The U-Th dating technique potentially provides absolute
chronological control for long-term tracer records in a single coral head or between corals from
different locations. The U-Th dating in our research means 238U-234U-230Th decay sequence, and
accurate U-Th dating requires distinguishing between a sample’s radiogenic 230Th and its non-
radiogenic 230Th -initial 230Th. Initial 230Th must be deduct from coralline ages because it can bias
true ages. Further, we will encounter some questions. First, the initial 230Th. Second,
uncertainties from isotopic composition in spike solution. Third, procedural blanks of 238U, 234U,
232Th, and 230Th. The best coral U-Th dating techniques (UMN and ANU groups) in the world can

only provide a precision of 2-3 years for corals younger than 100 years (after Edwards et al.,
1988), and we expect that we can achieve accuracy better than 6 month and 1 year for corals with
an age <200 and <400years, respectively. If we can attain accurate ages with few uncertainties, we
can apply to contrast global climate, dating past abrupt event, and long-term variability in
tropical cyclones, such as variability of the kuroshio ocean current around Taiwan east (future
                            Li Ming-Zhen

               Pollen and Charcoal Analysis in Taiwan Lake

The pollen analysis can presume past environmental change, including
climate, and vegetation. For example, pollen record already explained
timing and structure of climate change at Taipei Basin, Sun Moon Lake
and Tou-She, etc. About pollen study, lakes is a good study object. In this
study, we would make detailed research of pollen record at Yi-Lan
Shuang-Lain-Pi, Mei-Hua Lake. In resent year, charcoal fragments is also
important tool to explain vegetation event. Little is know about the role of
past fires as agens of vegetation change. In some study, forest fires do
occur in connection with human disturbance, especially during dry years,
with volcanic event such as pyroclastic flows and dry climate. The nature
charcoal and man-made charcoal have different meanings. In this paper, I
report pollen and charcoal record with high temporal resolution about
Taiwan and to understand application of pollen and charcoal in
paleoenviroment change.
                            Wang Zhen-Cheng
           I have joined the ‘Gas Geochemistry Group’ in NTU Geosciences
Department since 2001. The group leader is Professor T.F. YANG. When I got involved
in this group, YANG was planning to analyze NG (Noble Gases) in solid samples. So I
took that task as my researching field. In Geochemistry, NG is a good tracer for
Petrologic origins of rocks and minerals. However, to analyze NG in those solid
samples is not only different but also expensive. There are several reasons for that
difficulties, the major one is the nature scarcity of NG. Due to the scarcity, we need
high resolution Mass Spectrum and special designed extracting devices like vacuum
crasher to precede experiments. Nowadays I focus most of my researching on
developing and testing those devices. Once I finish that testing, I will start the next
procedure: analyzing NG in xenoliths in Taiwan. Xenoliths are found in several areas
in Taiwan, like PengHu, and most of those areas are often related to volcanism. If we
use NG in those xenoliths as a tracer, we could get the information about those
volcanisms, like depth, pressure, and most important of all, processes. In NG
geochemistry, the most significant element is Helium. There are two stable isotopes
about helium, 3He and 4He. Geochemistry scientists often use 3He∕4He ratio as an
indicator. 3He∕4He ratio in air is very homogeneous (1.39*10-6) and that ratio is
commonly used as global standard (1RA). From gas geochemistry viewpoint, the
helium isotopic ratio of the earth can be identified as four major components. (1) Air:
1 RA. (2) Crust: due to the radiogenic 4He, the 3He∕4He ratio in lower mantle is very low
(0.01~0.02 RA). (3) Upper mantle: MORB (8 RA). (4) Lower Mantle: primordial mantle
(>30 RA). If we combine NG data with other geochemistry data, NG will be a useful
tool for petrologic purposes.
                             Su Hong-zheng
          Knowledge sharing is the most important key of knowledge management.
Network community, also called virtual community, is the best solution in Internet or
Information Technology to communicate, interact and share information or
knowledge with others.
          One of the network communities will be observed and three issues will be
discussed: 1. What kinds of factors can improve the members’ inclination to share
their own knowledge? 2. What is the correlation between the process of knowledge
sharing and information technology? 3. How do influential factors interact with each
other? What the methodology is used is ―Case Study‖. There are three data
sources—deep interview, elementary descriptive statistics analysis and the
analysis of records in the database.
          Personal factors as well as group and organizational ones can influence
the inclination to share, which determines the sharing behavior. As for
organizational factors, leadership should be considered with first priority. Poor
information system will limit the sharing inclination of members. Using good
information system; however, cannot surely improve the sharing. Personal factors,
group factors, leadership, organizational culture and managerial system would
interact with each other. Moreover, the critical factor of the interaction is leadership.
There’s a distorting opinion on the correlation between knowledge sharing and
information system. Information system wouldn’t work without supporting factors,
such as leadership, managerial system and so on. In addition, Knowledge sharing
could be done well even without excellent information system.
                         Chen Kuan-Yu

Sources and distribution of arsenic in pore-water of Tainan, Southwestern


                      Kuan-Yu Chen, Tsung-Kwei Liu
 Department of Geosciences, National Taiwan University, Taipei, Taiwan

In order to understand the vertical distribution and mobilization of arsenic
in the subsurface strata of southwestern Taiwan, pore-waters and
sediments collected from a site in Tainan were analyzed. The high
concentration of arsenic of groundwater were distributive in the depth
about 100 to 200 meters. We infer that under reducing conditions caused
by microbially mediated processes, arsenic was released from Fe-Mn
hydroxides and combined with dissolved humic substances.
                          Chung Ling
In the last few years, apatite (U-Th)/He thermochronometry has became a
useful tool for quantifying the cooling histories of rocks. This technique
can give good interpretation of (is particularly suitable for study of ) near-
surface tectonic processes (which scientists and geologists are eager to
straighten out). (U-Th)/He dating is based on the radioactive decay of
parent isotope 232Th, 238U, 235U to daughter isotope 4He in the dating
minerals. Apatite is the most common mineral used in this method for its
lower closure temperature of helium (about 70℃) and its abundance of
uranium and thorium. By measuring the concentrations of uranium,
thorium and helium, we can get information about samples’ cooling
histories, further more, present possible explanation for local tectonic
processes. However, when using this technique, we have to concern about
the helium-diffusion characteristics which is controversial to adjust the
results of (U-Th)/He data. The size and shape is very important factors to
affect the helium retention of minerals, an at least 80 m radius crystal is
better for analyzed. After the samples are prepared, we have to analyze
helium by QMS and uranium, thorium by ICP-MS for their different phases.
The helium ages could be interpreted as the time of the sample’s cooling
through a specific closure temperature. So this technique could be used
not only to solve the Taiwan tectonic problems which have been remained
mysteries, but also to illustrate the landform evolution processes.
                             Huang Hsieh-Hsun
The observed upper ocean zonal current, 20°C isotherm depth, and zonal wind stress,
calculated from the European Centre for Medium Range Weather Forecasts
(ECMWF) model output, were examined in the equatorial Pacific during the period of
frequent Westerly Wind Bursts (WWBs) in October-April from 1988 (La Niña year) to
1992 (El Niño year). WWBs increased in strength and number, shifting eastwardly
towards El Niño and causing the frequent reversal of surface current and its vertical
gradient within the western basin. Similar features were also observed in the west-
central basin, but only during the El Niño event. The reversal of surface zonal current
in the central and eastern basins was generally accompanied by surfacing of the
Equatorial Undercurrent (EUC), though the vertical gradient of zonal current velocity in
the upper ocean never reversed. Fluctuations in upper ocean zonal currents in
response to the WWBs were largest in the western basin, while fluctuations in 20°C
isotherm depths were largest in the central and eastern basins. Discernible peaks in
ocean responses due to WWBs were modulated in their propagation away from the
forced region.
          Since WWBs occurred in succession at various locations, ocean responses
to each individual WWB were interfered with by other WWB events. A simple
analytical model was therefore devised to describe the temporal and spatial evolution
of the interference patterns in relation to various locations and WWB events. Pattern
evolutions for both upper ocean zonal current and thermal structures were further
modulated by easterly wind fluctuations east of the dateline. Tracing individual wave
modes using peak-to-peak comparisons is therefore a subjective process.
                       Suggested modification
The observed upper ocean zonal current, 20°C isotherm depth, and zonal wind
stress, calculated from the European Centre for Medium Range Weather
Forecasts (ECMWF) model output, were examined in the equatorial Pacific
during the period of frequent Westerly Wind Bursts (WWBs) in October-April
from 1988 (La Niña year) to 1992 (El Niño year). WWBs increased in strength
and number, shifting eastwardly towards El Niño and causing the frequent
reversal of surface current and its vertical gradient within the western basin.

The interaction between the upper zonal current and zonal wind stress
in the equatorialPacific was examined during the period of October to
April from 1988 (year of La Nina) to 1992 (year of Le Nino). The zonal
current refers to a depth of 20ºC isotherm, whereas the zonal wind
stress was calculated from the ECMWF (European Centre for Medium
Range Weather Forecasts). The period of October to April was chosen
because it contains frequent Westerly Wind Bursts (WWBs). The WWBs
increase in strength and number, and shift easterly, towards El Niño. They
cause frequent reversal of surface current and modify the vertical gradient
within the western basin.
                                    Lin Te-Hsien
  40Ar-39Ar   geochronological study of the Dien Bien Phu Fault, northern Vietnam

The Song Ma belt, a suture zone located in between the South China and Indochina blocks, was
offset by the Dien Bien Phu Fault (DBF) in northern Vietnam. Previous studies suggested that the
Dien Bien Phu Fault is one of the Tertiary shear zones, resulted from the Cenozoic extrusion
tectonics due to the India-Eurasia collision. However, the timing of the movement along DBF is
remained unknown due to lacking of age constraints. In order to reveal the movement age of the
DBF, schist samples from DBF and granites from the granite belt along the northern margin of the
Indochina block, were dated by the 40Ar-39Ar method in the present study. K-feldspar, hornblende,
and biotite samples form granite plutons yield very different age ranges between the opposite
sides of the DBF. Hornblende separates from an undeformed granite, on the west side, exhibit
plateau dates at around 277Ma. This age appears to be older than the early Triassic collision age
(~245Ma) registered in the Song Ma suture zone (Lepvrier et al., 1997), indicating that arc
magmatism may have actively occurred on the northern margin of the Indochina block, before the
early Triassic collision. On the other hand, the deformed granitic samples from the east side of
DBF exhibit plateau ages of 218-230 Ma which are younger than the collision age, which are close
to the age range previously reported for the Truong Son belt (a shear belt formed during or after
the early Triassic Indochina-South China collision event). Surprisingly, biotites and muscovites
extracted from the schists collected from the DBF, also show similar 40Ar/39Ar ages ranging form
192Ma to 211Ma, which are close to the deformation age of the Truong Son belt. This indicates
that the Dien Bien Phu Fault and the Truong Son Fault may have formed a conjugate fault system,
activated by the early Triassic collision event during the Indosinian Orogeny. Whether the Dien
Bien Phu Fault has once been reactivated by the Tertiary India-Eurasia collision, or not? This
question is still waiting for answer.
                                        Vicky Chen
Slip-rate Estimation of Active Fault by Luminescence Dating on Deformed River Terraces at Tsaotun,
                                           Central Taiwan
            This study carried out optical stimulated luminescence (OSL) ages of the tectonic-
disrupted terraces at Tsaotun, where the 1999 earthquake fault (i.e., Chelungpu) runs through. Over
there, a number of investigations have been done, but it is still difficult to evaluate the slip-rate and
recurrence interval without age control. For the purpose of understanding neotectonic behavior of
the Chelungpu fault, the ages of the terraces are imperative to be determined.
            Radiocarbon dating is unlikely applied in fluvial coarse deposits due to the fact that
syndepositional carbonaceous materials are easy to be decomposed. Alternatively, OSL dating is
therefore tried on sandy layers intercalated within massive gravel deposits found at Tsaotun. All the
terraces developed at Tsaotun are identified as strath terraces, indicating the depositional age is
very close to the surface age that is the best constraint in deriving the long-term slip rate of the
related active fault. (juzi taichang) Three samples are collected and presented. In this study only the
fraction of coarse quartz, i.e., 90-150 m, is sieved out and tested by the Single-Aliquot Regenerative
(SAR) dose protocol with 36 aliquots for each. Considering the incomplete bleaching during quick
deposition, the OSL/TL and OSL/OSL ratios are applied to normalization in each aliquot and to
approach the true De. Dose rate is derived by ICP-MS and XRF analyses. For confirmation of the
residual luminescence signals in the fluvial sediment, the modern samples collected in Wuhsi were
also measured using the same protocol.
            Based on the results of modern samples, we found that the residuals are inevitable in
younger samples, especially in the river reach where debris flow is dominant. On the contrary, the
samples older than 10 ka will be slightly influenced because the age error covers the residual
uncertainty. The OSL age of the terrace samples in the hanging wall is dated ca. 24 ka, which has
been corrected for poorly-bleaching problem. Comparing to the ages collected down hole in the
footwalls, we found out vertical displacements of ca. 72 m and 43 m, has been cumulated by the
slips of main and back thrust. Thus, the long-term slip rates of the main and back thrust are 2.7-3.3
m/ka and 1.8-2.2 m/ka, respectively.
                               Liu Ya-Jiun
Palaeoenvironment Study of Central Okhotsk Sea - Mineralogy, Geochemistry,
and Sediments Grain size of Core MD012414

          The North Pacific intermediate water (NPIW) influences the carbonate
preservation and the sink of anthropogenic carbon dioxide of the Pacific water, and even
(of?) the world oceanic water. It is believed that the NPIW originates from the Okhotsk Sea
intermediate water (OIW). The IMAGES (International Marine Past Global Change Study)
core MD012414 locating in the central part of Okhotsk Sea recorded the formation of OIW
and the palaeoclimate which was dominated by Asia monsoon. In this study, XRD, XRF,
and laser particle size analyses of bulk sediments have been proceeded to reconstruct
the northeastern Asian paleoclimatic and palaeoceanographic change for the last 500 ka.
          According to X-ray diffraction spectrums, the bulk sediments consist of mainly
quartz, plagioclase, calcite, halite, and some amorphous material, ordinary mineral
assemblage of pelagic sediments. The counts of calcite increase apparently during early
interglacial times. This implies that bottom water of the Okhotsk Sea was less oxygen at
that time. Calcite appearance is rare during the glacial stages, suggesting the ventilation
of OIW. The counts of halite and amorphous material, generally biogenic opal, increase
during interglacial stages 1, 3, and 5, suggesting a higher productivity and the
sedimentary rate was higher. Most of weight percentage ratios between major elements
and TiO2 show an apex at 120 ka, matching the counts peak of calcite in XRD analyses.
Sortable silt, 10-63um grain fraction, size analysis is used to establish the variation of
palaeocurrent intensity of OIW. It is found that the variation was coincident with the
orbital precession variation with a period of about 19 ka.
                            Hsaio Tun-Jen
          Nanocrystalline diamond (ND) was generally produced by (the) detonation
method. To discuss the mechanism of kinetics at explosion process is impossible,
because of analyses difficulty, the fast reaction time and hard to simulate the
environment. We propose to synthesize the ND by high-pressure (HP) and high-
temperature (HT) method, and to use the graphite encapsulated metals (GEM)
nanocrystals for the carbon substance and the metal catalyst. The effect of the
pressure, temperature and time on the conversion (phase transformation?)and on
the crystal structure will be investigated (carefully examined). In addition, we will try
to explore the complex formation mechanisms of phase transformation at nanoscale.
          The GEM (5-100 nm) nanocrystals have been used to synthesize diamond
in this project, (?) with an inner core of ferromagnetic materials encapsulated and
protected by several layers of graphite. The advantages of using GEM are; (a) the
nanoscale grain size represents the conversion during the phase transformation
process, (b) the simple mechanism of atom shift between the carbon substance and
the encapsulated metal catalyst, and (c) the layer of GEM is without 2H type
structure, and therefore, it becomes diamond by (the) HT, HP (HP-HT) method.
          The stable phase field of diamond obtain the pressure and the temperature
yield using diamond anvil apparatus (?). The phase transformation process is
studied and continuously observed in situ by Raman Scattering Spectroscopy (RS)
and XRD. Kinetics model will discuss the mechanisms of GEM to ND transformation.
The characters of ND are not just having hardness, wear resistance, erosion
resistance and high thermal conductivity, but also having large specific surface area
and field emission of cold cathodes. Therefore, ND is the best material.
                          Fu Ching-Chou 2a

           Recognition of buried fault and/or fracture by
                        the soil gas method
           Taiwan is located on the boundary between Eurasia plate and Philippine Sea
plate. The continuous stress and collision make Taiwan densely faulted. Therefore, to
find out the distribution of faults is the need of hour and requires urgent attention for
disaster prevention. So far most of the research has been based on geophysical
techniques, trench studies and structure geology. Nevertheless, geochemical methods
were rarely used in Taiwan. Study of soil gases has already been used to investigate
petroleum, uranium mineral and geothermal etc. for a long time in the world and some
studies have demonstrated the feasibility to explore blind faults and/or fractures by soil
gas method. (Etiope and Lombardi, 1995; Fytikas et al., 1999; Guerra and Lombardi,
2000; Baubron et al., 2001). Generally, gas compositions are entirely different in air
and deep-crust derived components. The later will diffuse upward to the surface and
balance with the air. That‟s why soil gas compositions are rather different from air.
Deep faults or fractures underlie the surface may provide gases the conduits to migrate
upward from deep crust or mantle which produces anomalously high deep source
signatures in the soil above. We can apply this principle to trace the faults or fractures
which pass through the region under study.
                           Fu Ching-Chou 2b
            In early years, some researchers have tried to use this method to prospect the
fault distributions in Taiwan (refs.). The results were not satisfactory, however, due to
number of limitation in the analytical technique with less accuracy, hence the method
was not adopted extensively. With the improvement in instrumentation it is possible to
have instant analyses of soil gas compositions in field. So we can condense the
distributions of sample points to judge the anomaly more accurately. Furthermore,
matching with other geophysical and geological data the location of faults/fractures on
the surface can be determined more accurately.
            To test this method Chaochou Fault in Pingtung region has been selected for
present study, because this area is less developed and might contain obvious fault
characteristics. For soil-gas sampling, a hollow steel probe is inserted into the soil at the
depth of about 100 cm and a hand-pump is used to accumulate gas into a sample bag.
During this study, more than 222 soil-gas samples were collected along several traverses
crossing the observed structures, with the sampling interval of about 250~300 m.
            Preliminary results show that helium and carbon dioxide concentration in the
soil gas reveals anomalous values for specific positions along each of the traverses. It
indicates N-S trending faults and/or fractures which corresponds to the reported trend
and pattern of the Chaochou Fault. Besides the Chaochou Fault, we can also recognize
several N-S trending fractural structures distributed in this area. Hence, the soil gas
method is considered to be suitable for the exploration of buried faults and/or fractures,
at least in SW Taiwan.
          Quiz 2 - Translation
海洋山脊形成的新机制(Ocean ridges: then there were three)

(Articles, p. 405; News and Views)

机制 mechanism 海床擴展 sea-floor spreading      擴展速度 spreadomg rate

北冰洋山脊 Arctic Ridge   超慢擴展山脊 ultraslow spreading ridge

地幔上涌 mantle upwelling        共存的 co-existing     岩漿增長 magmatic a

增長邊界 accretionary boundary
Deng Xiaoping earned 400 yuans (RMB) per month in 1982

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