| 大别造山带南缘鄂京地1井笔石生物地层与黑色页岩的构造重复 |
| 投稿时间：2025-10-17 修订日期：2026-01-04 |
| 关键词:Well EJD-1, black shale, graptolite biozone, shale gas, strata repetition |
| 基金项目:国家自然科学基金项目"湘鄂西地区下志留统黑色页岩内部沉积间断识别与古地理重建"（42172038）及中国地质调查局地调项目（DD20230006） |
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| 摘要: |
| The graptolite biostratigraphy and the repetition of the black shale in the Well EJD-1 on the southern margin of the Dabie Orogenic Zone |
| The black shale of the Ordovician Wufeng Formation and the Silurian Longmaxi Formation in the Well EJD-1 on the southern margin of the Dabie Orogenic Zone is the target bed for shale gas exploration. Based on the study of graptolite biostratigraphy of the drill core, it was found that there is a repetition of the graptolite sequence from Cystograptus vesiculosus to Demirastrites triangulatus biozones in the lower part of the well (depth 1450.45m - 1425.5m) and the middle part of the well (depth 940m - 864m). In the middle-upper part of the well, there are 3 repetitions of the graptolite sequence from D. triangulatus to Pribylograptus leptotheca biozones. However, the lower part of the strata in the well is gentle inclined, while the middle and upper parts of the strata are nearly vertical. Therefore, the repetition between the strata in the lower and middle parts is due to structural repetition, while the multi-repetition of the D. triangulatus to P. leptotheca biozones in the middle-upper part of the well are caused by the steep dip of the strata. The Well EJD-1 and its adjacent wells shows that the black shale has low gas content in this region. The structural repetition of the black shale in the Well EJD-1 indicates that the tectonic preservation conditions for the shale gas on the southern margin of the Dabie Orogenic Zone are complex. Further investigation is needed for the resource potential of the shale gas and the exploration risk of the shale gas is relatively high in this region. |
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