CAJ | 학술논문

北黄海盆地X钻井岩心揭示了中生界两套碎屑岩系：下部的暗色岩系和上部的红色岩系。暗色岩系底部和顶部存在两层火山岩。下层火山岩的岩石学鉴定为粗面英安岩，化学成分位于英安岩–流纹岩分区，靠近粗面英安岩分区。上层火山岩的岩石学鉴定为碎屑碎斑英安岩，化学成分位于英安岩分区。下层和上层火山岩锆石的阴极发光图像显示出自形–半自形柱状的晶形和韵律环带结构，下层粗面英安岩中22颗锆石的206Pb/238U年龄介于141~151 Ma之间，其加权平均年龄为145±2 Ma。上层碎屑碎斑英安岩中18颗锆石的206Pb/238U年龄介于139~149 Ma之间，其加权平均年龄为141±2 Ma。反映X井火山岩属于晚侏罗世晚期–早白垩世早期，因此这套暗色岩系应为晚侏罗世–早白垩世地层。对比山东半岛中生代岩浆作用的年代学和地球化学资料发现，北黄海盆地与胶莱盆地火成岩可能具有相同的动力学机制，形成于与俯冲有关的火山弧或弧后伸展环境背景。
북황해분지X찬정암심게시료중생계량투쇄설암계：하부적암색암계화상부적홍색암계。암색암계저부화정부존재량층화산암。하층화산암적암석학감정위조면영안암，화학성분위우영안암–류문암분구，고근조면영안암분구。상층화산암적암석학감정위쇄설쇄반영안암，화학성분위우영안암분구。하층화상층화산암고석적음겁발광도상현시출자형–반자형주상적정형화운률배대결구，하층조면영안암중22과고석적206Pb/238U년령개우141~151 Ma지간，기가권평균년령위145±2 Ma。상층쇄설쇄반영안암중18과고석적206Pb/238U년령개우139~149 Ma지간，기가권평균년령위141±2 Ma。반영X정화산암속우만주라세만기–조백성세조기，인차저투암색암계응위만주라세–조백성세지층。대비산동반도중생대암장작용적년대학화지구화학자료발현，북황해분지여효래분지화성암가능구유상동적동역학궤제，형성우여부충유관적화산호혹호후신전배경배경。
The X-drilling cores of the North Yellow Sea basin reveal two sets of Mesozoic clastic rocks, which are the dark rocks in lower part and the red rocks in upper part, respectively. There are two layers of volcanic rocks at the bottom and the upper part of the dark rock unit. The volcanic rocks at the bottom part are trachytic dacite while rocks at the upper part are clastic dacite. The zircon grains from the upper and lower units of volcanic rocks are euhedral-subhedral columnar crystals and show oscillatory zoning on cathodoluminescence images. 22 tests of zircons in the trachytic dacite from the bottom part yield an age of 141–151 Ma, with weighted mean 206Pb/238U age of 145±2 Ma. Whereas 18 tests of zircons from the sample at the upper part give206Pb/238U ages around 139–149 Ma with weighted mean206Pb/238U age of 141±2 Ma, which implies that the X well volcanic rocks belong to Late Jurassic-Early Cretaceous. Comparing with the age and geochemical characteristics of the Mesozoic igneous rocks in Shandong peninsula, we suggest that the igneous rocks from both the North Yellow Sea basin and Jiaolai basin were formed under same dynamic setting, i.e., the subduction related volcano arc and back-arc extension.