Characteristics of Cenozoic volcanic edifices in the Pingnan area, Xihu Sag
Significance Igneous rocks are well-developed in the southern Pinghu slope zone, Xihu Sag, East China Sea Shelf Basin. In this zone, the increased local geotemperature caused by magmatic activity produced significant impacts on the thermal evolution of source rocks and the formation of secondary por...
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| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | zho |
| Published: |
Editorial Office of Coal Geology & Exploration
2025-01-01
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| Series: | Meitian dizhi yu kantan |
| Subjects: | |
| Online Access: | http://www.mtdzykt.com/article/doi/10.12363/issn.1001-1986.24.05.0324 |
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| Summary: | Significance Igneous rocks are well-developed in the southern Pinghu slope zone, Xihu Sag, East China Sea Shelf Basin. In this zone, the increased local geotemperature caused by magmatic activity produced significant impacts on the thermal evolution of source rocks and the formation of secondary pores in sandstone reservoirs and also serves as a significant indicator of regional tectonic movements, thus holding great significance for understanding the regional geological history. Objective and Methods This study aims to determine the formation stages and distribution patterns of igneous rocks as the cap rocks in the southern Pinghu slope zone. Using previous study results and the data of adjacent areas, as well as 3D seismic data and related attributes, and data from drilling and logs, this study analyzed the types, corresponding strata, and distribution ranges of volcanic rocks in the southern Pinghu slope zone. Furthermore, the formation stages of igneous rocks in the slope zone were explored based on the stratigraphic chronology, the morphologies of volcanic edifices, and the contact relationship between volcanic edifices and surrounding rocks. Results and Conclusions The results indicate that the seismic facies of igneous rocks in the Pingnan area can be divided into volcanic vent facies, along with explosive, overflow, and intrusive facies, with mounded and shield volcanic edifices proving the most developed. The magmatic activity in the Xihu Sag can be divided into three stages. Specifically, magmatic activity during the regional Longjing Movement, occurring in the late Miocene, exhibits the highest intensity and widest influence range. Besides, local small-scale tectonic movements occurred in the late depositional stage of the Yuquan Formation and the early depositional stage of the Santan Formation, corresponding to weak magmatic activity with minimal impacts. The Pingnan area contains five lithologic, low-amplitude drape anticline/fault combination traps associated with magmatic activity. The results of this study will provide a reference for future hydrocarbon exploration and production in the southern Pinghu slope zone of the Xihu Sag. |
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| ISSN: | 1001-1986 |