Stratigraphic correlation of Cretaceous non-marine sedimentary basins of Southeast Korea and Southwest Japan

被称为庆尚群的白垩纪非海相沉积岩在韩半岛东南部分布广泛。本研究得到以下结果：(1)位于庆尚盆地北部的永阳地区的庆尚群主要由砂岩、砾岩和红粉砂岩组成。该砾岩虽然非常罕见，但在某些层位含有燧石碎屑。几块巧克力棕色燧石碎屑产生了保存完好的二叠纪放射虫，属于卵泡群。(2)上述白垩系砾岩基质砂岩中含有电气石、不透明石、锆石、独居石等重质矿物。碎屑独居石的CHIME年龄为中元古代约1500 Ma，二叠纪-三叠纪界线年龄约250 Ma。(3)春州东南玉川带黑色千粒岩和片岩中零星含有石英岩、花岗质、泥灰岩和灰岩等碎屑。花岗质片麻岩碎屑产生的CHIME独居岩年龄为1450 Ma，表明玉川碎屑岩物源中存在中元古代花岗质和片麻岩。(4)春州坝附近裸露的玉川变质岩由变质岩、白云岩、石英岩和变质长岩组成。产于玄武岩凝灰岩的含石榴石的放线石绿帘石片岩中含有约250 Ma CHIME年龄的allanite。这个时代可能代表了玉川片岩的区域变质作用时期。

Cretaceous non-marine sedimentary rocks called the Kyongsang Group are widespread in the southeastern Korean Peninsula. The following results were obtained from this research.(1) The Kyongsang Group in the Yongyang area that occupies the northern part of the Kyongsang Basin consists mainly of sandstone, conglomerate and red siltstone. The conglomerate, although very rare, contains chert clasts in some horizons. Several chocolate brown chert clasts yielded well-preserved permian radiolarians of the Follicucullus group.(2) The matrix sandstone of the above Cretaceous conglomerate contains such heavy minerals of tourmaline, opaques, zircon and monazite. The detrital monazites yielded CHIME ages of ca.1500 Ma of middle Proterozoic age and ca.250 Ma of Permian-Triassic boundary age.(3) Black phyllite and schist in the Okchon Belt to the southeast of Chunju sporadically contain clasts of quartzite, granitoid, marl and limestone. The granitic gneiss clasts yielded CHIME monazite ages of 1450 Ma, suggesting that middle Proterozoic granite and gneiss were present in the provenance of Okchon clastic rocks.(4) The Okchon metamorphic rocks exposed near the Chunju dam consist of metabasite, dolomite, quartzite and metapelite. Garnet-bearing actinolite-epidote schist of basaltic tuff origin contains allanite that yields CHIME ages of ca.250 Ma. This age probably represents the time of regional metamorphism of the Okchon schists.