Stratiform Sulfide Ore Deposits of the Upper Palaeozoic in Eastern Chugoku and Western Kinki Regions, Southwestern Japan
Stratiform Sulfide Ore Deposits of the Upper Palaeozoic in Eastern Chugoku and Western Kinki Regions, Southwestern Japan
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日本西南部东部中国和西部近畿地区上古生界层状硫化物矿床
DOI：
10.11456/shigenchishitsu1951.38.247
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发表时间：
1988
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影响因子：
--
通讯作者：
C. Mitsuno
中科院分区：
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作者：
C. Mitsuno
中国东部和近畿西部地区的石炭纪和二叠纪海底火山岩及其变质岩中存在许多层状硫化物矿床。可分为三类：（1）三群变质带真庭群下部地层石炭系基性片岩矿床（别子型层状硫化物矿床）； (2)二叠系基性片岩、舞鹤群下层基性火山岩矿床(别子型层状硫化物矿床)； (3)二叠系舞鹤群中层酸性火山岩矿床(柳原型层状硫化物矿床)。所有矿床都经历了三次褶皱：晚古生代至早三叠世（三群变质作用）、中三叠世和侏罗纪。柳原和福泽矿床也受到白垩纪花岗岩接触变质作用的影响。尽管母火山岩的年龄和酸度存在差异，但这些矿床的硫同位素比显示出显着的均匀性，范围为+0.6至+2.99•ñ。别子型和柳原型矿床都是火山喷发矿床。别子型矿床与碱性海底火山作用有成因关系，而柳原型矿床则与酸性海底火山作用有关。引言 自1951年以来，作者一直致力于中国东部和近畿西部地区上古生界的火山地层研究，以澄清与层状硫化物矿床伴生的基性和酸性火山岩的地层关系（MITSUNO，1953，1959，1960，1963；MISTUNO等，1965，1975， 1983 年、1986 年）。津山市西北部有一个由板岩、砂岩和燧石组成的弱变质岩层。以前它被认为是古生代；然而，最近通过对牙形刺化石的检查，确定其为早三叠世（TOYOHARA，1979）。其分布如图1所示，称为低级变质三叠系。关于该地区钙质相与非钙质（特别是基性火山岩）之间的关系，如逆冲断层、整合面、橄榄岩等，一直有很多讨论。其中，MIYAKE（1985）的观点值得注意。他提到，扁线虫的分布仅限于胜山地区神波瀑布西部地区；东部地区保存完好，由绿岩、石灰岩、砂岩、页岩互层组成，呈东西走向，由上至下排列。根据现场证据，作者接受了厚钙质相（如阿铁灰岩群）整合覆盖在基性岩之上的观点。基于这一假设，本研究的目的是确认钙质相和非钙质相之间的地层相关性，接收日期为 1986 年 12 月 1 日，接受日期为 1988 年 3 月 17 日。 * 本研究的一部分于 1983 年日本矿业地质学会会议上提出。 ** 冈山大学理学院地球科学系。
In eastern Chugoku and western Kinki regions there are a number of stratiform sulfide ore deposits in Carboniferous and Permian submarine volcanic rocks and their metamorphic equivalents. They can be classified into three groups: (1) ore deposits in Carboniferous basic schist of the lower formation of the Maniwa Group of the Sangun metamorphic zone (Besshi-type stratiform sulfide ore deposits); (2) ore deposits in Permian basic schist and basic volcanic rocks of the lower formation of the Maizuru Group (Besshi-type stratiform sulfide ore deposits); (3) ore deposits in Permian acidic volcanic rocks of the middle formation of the Maizuru Group (Yanahara-type stratiform sulfide ore deposits). All ore deposits were folded three times: Late Paleozoic to Early Triassic (Sangun metamorphism), Middle Triassic and Jurassic ages. The Yanahara and Fukuzawa ore deposits were also influenced by contact metamorphism caused by Cretaceous granitic rocks. These ore deposits show a remarkable uniformity in sulfur isotope ratio, ranging from +0.6 to +2.99•ñ, despite the differences in age and acidity among the host volcanic rocks. Both the Besshi-and Yanahara-type ore deposits are volcanic exhalative in origin. The Besshi-type ore deposits are genetically related to basic submarine volcanism, whereas the Yanahara-type ore deposits are related to acidic submarine volcanism. Introduction Since 1951 the writer has engaged in volcano -stratigrahical study of the Upper Paleozoic in eastern Chugoku and western Kinki regions in order to clarify the stratigraphic relation of the basic and acidic volcanic rocks which are associated with stratiform sulfide ore deposits (MITSUNO, 1953, 1959, 1960, 1963; MISTUNO et al., 1965, 1975, 1983, 1986). A weakly metamorphosed formation, comprising slates, sandstones and cherts, occurs northwest of Tsuyama City. Previously it was considered to be Paleozoic; however, it was recently detemrined to be Early Triassic by examination of conodont fossils (TOYOHARA, 1979). Its distribution is shown in Fig. 1, and is called the low grade metamorphosed Triassic Group. There has been much discussion regarding the relation between calcareous facies and non-calcareous (particularly basic volcanic) rocks in the region, i.e., thrust, conformity, olistostrome and so on. Of these, the view of ,MIYAKE (1985) is worthy to note. He mentioned that the distribution of the olistostrome is restricted to the western area of the Kamba Fall, Katsuyama district; the original stratigraphical succession, made up of greenstone, limestone and alternating beds of sandstone and shale in ascending order, and trending east-west, is well preserved in the eastern area. On the basis of field evidence, the writer has accepted the view that the thick calcareous facies (e.g., the Atetsu Limestone Group) conformably overlies the basic rocks. Based on this hypothesis, the purpose of this study is to confirm the stratigraphic correlation between the calcareous and non-calcareous facies in Recived on December 1, 1986, accepted on March 17, 1988. * A part of this study was presented at the Meeting of the Society of Mining Geologists of Japan, 1983. ** Department of Earth Sciences , Faculty of Science, Okayama University.