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Cheng-Chao Lee Louis Loung-Yie Tsai Chieh-Hou Yang Kuo-Liang Wen Zi-Bin Wang Zhi-Hsian Hsieh Hsing-Chang Liu 《Environmental Geology》2009,58(7):1397-1406
A slope on the west border of the foothill near 921 surface rupture (caused by the 1999 Chi-Chi earthquake) in central Taiwan
shows distinctive topographic expression that was prone to be considered as a fault scarp formed by a preexisting active fault.
The 2D and 3D resistivity images clearly delineate rock surfaces which show steep, deep, gentle, and subvertical displacement
beneath the slope, the toe of slope, the non-lateritic terrace, and 921 surface rupture, respectively, which can be attributed
to the significant contrast of resistivity between gravel and rock. The horizontal sand bed and clast-supported gravel were
deposited in a fluvial environment, whereas wedge-shaped gravel and colluvium were scarp-induced colluvial deposits in the
trench profile. The layers shown in the depth of excavation, except for rock, has no offset or disturbance by fault ever since
at least 2,480 ± 50 year B.P., based on carbon 14 dating of charcoal sample at the bottom of trench profile. According to
information from two boreholes close to the slope, an over 20-m-thick marker bed with transported shell fragments, was found
for correlation. This correlation further implies the slope was not formed by fault. On the other hand, two boreholes which
are far from the slope and located on the flat non-lateritic terrace frequently show fractured and sheared features. By comparison,
the locations around these two boreholes indicate a reverse fault or faults that occurred before the deposition of gravel.
Later on, the paleostream was developed along the foot of fault scarp that was subjected to erosion and led to subsequent
retrogression or retreat of the slope. Consequently, the incision of paleostream is believed to be responsible for the high
relief of rock surface around the slope. Furthermore, from resistivity and borehole data, the rock surface underlying terrace
is gentle where no faults occur after the deposition of gravel. The result of RIP crossing the 921 surface rupture displays
about 10 m difference in elevation of rock surface on both sides, which is greater than that of 3–4 m caused by Chi-Chi earthquake.
This indicates that the 921 surface rupture is a preexisting thrust fault that resulted from several thrusting events since
terrace gravel was deposited. So it is not necessary to establish an extra restricted zone for construction in study area,
except close to the 921 surface rupture. 相似文献
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HIEU Pham Trung 《地球学报》2015,36(6):755-760
本文对越南西北部Phan Si Pan地区变质地体中的一个Ngoi Chi片麻岩进行了锆石CL内部结构分析、LA-(MC)-ICP-MS锆石U-Pb定年和Hf同位素分析。CL图象和Th/U比值特征显示该片麻岩样品中的锆石主要为岩浆锆石,有少量窄的变质边。岩浆锆石的年龄为~2.9 Ga,表明该样品是越南西北部Phan Si Pan地区的基底岩石。它们的εHf(t)值为–4.70±0.92,二阶段Hf模式年龄为~3.5 Ga,表明其为更古老的(3.5 Ga)冥太古代地壳物质部分熔融作用形成。变质边部锆石给出了~1.8 Ga的年龄,表明变质作用发生在古元古代早期,Phan Si Pan地区在这一时期可能经历了一次重要的构造热事件。 相似文献
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快速测定矿石中的银：二苯硫脲泡塑富集分离硫代米Chi酮—洗洁精全差示光度？ 总被引：2，自引：0，他引：2
提出了一个二苯硫包塑富集分离硫代米Ｃｈｉ酮－洗洁精全差示光度法快速测定矿石中银的新方法。该法简单快速,准确度高,选择性好,易于操作,适用性好,易于操作,适用于野外和中小型矿山化验室快速测定矿石中的银。 相似文献