| Summary: | 碩士 === 國立臺北科技大學 === 資源工程研究所 === 106 === The alluvial layer of at least 400 meters to 600 meters thick in the Sanxing area of the Yilan Plain is an important factor for understanding whether the rock formation beneath belongs to the Hsuehshan Range Belt or the Backbone Range Belt. This study utilizes the cores and cuttings from 4 wells, SanXing #1 (depth 602 m), JieYuan #1 (depth 1438 m), HongChaiLin #1 (depth 2225 m) and HongChaiLin #2 (depth 2800 m), performs the petrographic analysis and mineral composition, and compares with that off the foothills surrounding the Yilan Plain, in order characterize the basement rocks in the Sanxing area and intent to identify the origin of the stratum.
Based on the cores and cuttings, (1) the thin sections from SanXing #1 well show the parallel disjunctive cleavage from the depth of 469 to 539 meters, and the anastomosing disjunctive cleavage after 539 meters in depth. The mineral composition and content ratios are 75%-85% for illite, 15%-25% for chlorite, and 0.26-0.38Δ°2θ for the crystallinity of the illite. (2) The thin sections from Jieyuan #1 well show the parallel disjunctive cleavage from the depth of 732 to 759 meters and from the depth of 771 to 908 meters, and the anastomosing disjunctive cleavage from the depth of 762 to 770 meters. The mineral composition and content ratios are 72%-90% for illite, 10%-28% for chlorite, and 0.22-0.39 Δ°2θ for the crystallinity of the illite. (3) The thin sections from HongChaiLin #1 well show the anastomosing disjunctive cleavage from the depth of 450 to 850 meters, and the parallel disjunctive cleavage from the depth of 850 to 2050 meters. The mineral composition and content ratios are 75%-86% in the depth of 450 meters to 1250 meters, 87%-98% in the depth 1250 meters to 2150 meters for illite, 14%-25% in the depth 450 meters to 1250 meters, 2%-13% in the depth 1250 meters to 2150 meters for chlorite and kaolinite, and 0.23-0.33 Δ°2θ for the crystallinity of the illite. (4) The thin sections from HongChaiLin #2 well show the parallel disjunctive cleavage from the depth of 900 to 1000 meters, and the anastomosing disjunctive cleavage at other depths. The mineral composition and content ratios are 80%-90% in the depth of 500 meters to 1000 meters, 91%-99% in the depth 1000 meters to 1800 meters, 82%-88% in the depth 1800 meters to 2800 meters for illite, 10%-20% in the depth 500 meters to 1000 meters, 0%-9% in the depth 1000 meters to 1800 meters, 12%-18% in the depth 1800 meters to 2800 meters for chlorite and kaolinite, and 0.26-0.34 Δ°2θ in the depth 500 meters to 1000 meters, 0.37-0.47 Δ°2θ in the depth 1000 meters to 1300 meters, 0.2-0.34 Δ°2θ in the depth 1300 meters to 2800 meters for the crystallinity of the illite. From the field samples, (a) the stratigraphic characteristics off the northern foothills of Yilan are characterized by, (1) the slate of Hsitsun Fm shows the anastomosing disjunctive cleavage. The content ratios of the illite is 80%-87%, and the chlorite and kaolinite is 13%-20%. the crystallinity of the illite is 0.25-0.28Δ°2θ. (2) The metamorphic sandstone of the Szeleng Ss shows no cleavage, the content ratio of illite is 99%-100%, the chlorite and kaolinite account for 1%, and the crystallinity of illite is 0.25-0.50 Δ°2θ. (3) the slate of Kankou Fm shows the parallel disjunctive cleavage, the illite content is 71%-81%, and the chlorite and kaolinite are between 19%-29%. the crystallinity of the illite is 0.25-0.35 Δ° 2θ. (b)Stratigraphic characteristics of the foothills of the southern Yilan, (1) The metamorphic sandstone of Lushan Fm shows no cleavage, with 99%-100% of the illite, 0%-2% of the kaolinite and chlorite, and 0.32 -0.45Δ°2θ of the crystallinity of illite. (2) The slate of Lushan Fm shows the anastomosing disjunctive cleavage, the illite content is 75%-89%, and the chlorite and kaolinite account for 11%-25%. The crystallinity of illite is 0.42-0.58Δ°2θ. (3) The slate of Suao Fm shows the parallel disjunctive cleavage, the content ratio of illite is 67%-76%, the content of chlorite and kaolinite is 24%- 33%, and the crystallinity of illite is 0.25-0.35 Δ ° 2θ.
Finally, the results of the study from the petrography and mineral composition of the underground cores/cuttings verses surface rock samples indicate that the SanXing #1 well is similar to the Kankou Fm; the JieYuan #1 well is similar to the Kankou Fm; the HongChaiLin #1 well is similar to the Kankou Fm at a depth of 450 to 1250 meters, and is similar to the Szeleng Ss at a depth of 1,250 to 2,150 meters; the HongChaiLin #2 well is similar to the Kankou Fm at a depth of 500 to 1300 meters, and is similar to the Szeleng Ss at a depth of 1300 to 2800 meters. Concluded data from all four wells between the depth of 450 and 2800 meters, the slate and metamorphic sandstone in the underground strata of the SanXing area could be divided into Kankou Fm and Szeleng Ss.
|
|---|
