Quartz Origins and Paleoenvironmental Controls on Organic Matter Accumulation of Marine Shale in the Ordovician Wulalike Formation, Northwestern Ordos Basin, China: Significance for Shale Gas Exploration
The Ordovician Wulalike marine siliceous shale is a notable hydrocarbon source rock in the Northwestern Ordos Basin. However, the causes of quartz and organic matter enrichment are still a mystery to experts. In this study, the organic geochemistry (maceral compositions, R<sub>bitu</sub>...
| Main Authors: | , , , , , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2023-07-01
|
| Series: | Energies |
| Subjects: | |
| Online Access: | https://www.mdpi.com/1996-1073/16/14/5278 |
| _version_ | 1827733264798842880 |
|---|---|
| author | Yanni Zhang Rongxi Li Shengli Xi Jianwen Gao Lei Chen Hexin Huang Bangsheng Zhao Ahmed Khaled |
| author_facet | Yanni Zhang Rongxi Li Shengli Xi Jianwen Gao Lei Chen Hexin Huang Bangsheng Zhao Ahmed Khaled |
| author_sort | Yanni Zhang |
| collection | DOAJ |
| description | The Ordovician Wulalike marine siliceous shale is a notable hydrocarbon source rock in the Northwestern Ordos Basin. However, the causes of quartz and organic matter enrichment are still a mystery to experts. In this study, the organic geochemistry (maceral compositions, R<sub>bitu</sub>, and TOC) and elemental geochemistry (major and trace elements) with mineralogy (XRD) and petrography were jointly acquired to systematically investigate the quartz origins and the paleoenvironment, and the main controlling factors for organic matter enrichment in the Wulalike shale. The results show that the organic matter is type I kerogen with low TOC concentrations (average 0.51%), and that the thermal evolution has reached mature and high mature stages (mean R<sub>equ</sub> is 1.08%). Three types of quartz are developed in Wulalike shale: biogenic quartz (average 63%) is the most dominant, followed by clastic quartz (average 31%) and microcrystalline quartz (average 6%). Babio and Ba/Al values indicate the low paleoproductivity, which is the primary cause for the low TOC found throughout the area. Redox indexes show the anoxic or dysoxic to oxic conditions from the bottom to the top of the section. Paleoclimate and paleowater depth proxies also changed from the bottom to the top. Various paleoenvironments and sedimentological evidence show that Wulalike shale went through the changing environments, and the early sedimentary environments were conducive to organic matter enrichment, leading to a relatively high TOC. The paleoproductivity and preservation conditions have an impact on organic matter enrichment. Based on the results of biogenic quartz distribution and sedimentary environments, it is considered that the bottom of the Wulalike Formation is the most favorable for shale gas exploration and development. |
| first_indexed | 2024-03-11T01:08:10Z |
| format | Article |
| id | doaj.art-bfc5bd4e950247fea814961fb25b0971 |
| institution | Directory Open Access Journal |
| issn | 1996-1073 |
| language | English |
| last_indexed | 2024-03-11T01:08:10Z |
| publishDate | 2023-07-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Energies |
| spelling | doaj.art-bfc5bd4e950247fea814961fb25b09712023-11-18T19:07:59ZengMDPI AGEnergies1996-10732023-07-011614527810.3390/en16145278Quartz Origins and Paleoenvironmental Controls on Organic Matter Accumulation of Marine Shale in the Ordovician Wulalike Formation, Northwestern Ordos Basin, China: Significance for Shale Gas ExplorationYanni Zhang0Rongxi Li1Shengli Xi2Jianwen Gao3Lei Chen4Hexin Huang5Bangsheng Zhao6Ahmed Khaled7School of Earth Science and Resources, Chang’an University, Xi’an 710054, ChinaSchool of Earth Science and Resources, Chang’an University, Xi’an 710054, ChinaPetroChina Changqing Oilfield Company, Xi’an 710018, ChinaResearch Institute of Exploration and Development, PetroChina Changqing Oilfield Company, Xi’an 710018, ChinaSchool of Geosciences, China University of Petroleum (East China), Qingdao 266580, ChinaSchool of Earth Science and Resources, Chang’an University, Xi’an 710054, ChinaSchool of Earth Science and Resources, Chang’an University, Xi’an 710054, ChinaSchool of Earth Science and Resources, Chang’an University, Xi’an 710054, ChinaThe Ordovician Wulalike marine siliceous shale is a notable hydrocarbon source rock in the Northwestern Ordos Basin. However, the causes of quartz and organic matter enrichment are still a mystery to experts. In this study, the organic geochemistry (maceral compositions, R<sub>bitu</sub>, and TOC) and elemental geochemistry (major and trace elements) with mineralogy (XRD) and petrography were jointly acquired to systematically investigate the quartz origins and the paleoenvironment, and the main controlling factors for organic matter enrichment in the Wulalike shale. The results show that the organic matter is type I kerogen with low TOC concentrations (average 0.51%), and that the thermal evolution has reached mature and high mature stages (mean R<sub>equ</sub> is 1.08%). Three types of quartz are developed in Wulalike shale: biogenic quartz (average 63%) is the most dominant, followed by clastic quartz (average 31%) and microcrystalline quartz (average 6%). Babio and Ba/Al values indicate the low paleoproductivity, which is the primary cause for the low TOC found throughout the area. Redox indexes show the anoxic or dysoxic to oxic conditions from the bottom to the top of the section. Paleoclimate and paleowater depth proxies also changed from the bottom to the top. Various paleoenvironments and sedimentological evidence show that Wulalike shale went through the changing environments, and the early sedimentary environments were conducive to organic matter enrichment, leading to a relatively high TOC. The paleoproductivity and preservation conditions have an impact on organic matter enrichment. Based on the results of biogenic quartz distribution and sedimentary environments, it is considered that the bottom of the Wulalike Formation is the most favorable for shale gas exploration and development.https://www.mdpi.com/1996-1073/16/14/5278Ordos BasinWulalike Formationbiogenic quartzpaleoenvironmentsorganic matter accumulation |
| spellingShingle | Yanni Zhang Rongxi Li Shengli Xi Jianwen Gao Lei Chen Hexin Huang Bangsheng Zhao Ahmed Khaled Quartz Origins and Paleoenvironmental Controls on Organic Matter Accumulation of Marine Shale in the Ordovician Wulalike Formation, Northwestern Ordos Basin, China: Significance for Shale Gas Exploration Energies Ordos Basin Wulalike Formation biogenic quartz paleoenvironments organic matter accumulation |
| title | Quartz Origins and Paleoenvironmental Controls on Organic Matter Accumulation of Marine Shale in the Ordovician Wulalike Formation, Northwestern Ordos Basin, China: Significance for Shale Gas Exploration |
| title_full | Quartz Origins and Paleoenvironmental Controls on Organic Matter Accumulation of Marine Shale in the Ordovician Wulalike Formation, Northwestern Ordos Basin, China: Significance for Shale Gas Exploration |
| title_fullStr | Quartz Origins and Paleoenvironmental Controls on Organic Matter Accumulation of Marine Shale in the Ordovician Wulalike Formation, Northwestern Ordos Basin, China: Significance for Shale Gas Exploration |
| title_full_unstemmed | Quartz Origins and Paleoenvironmental Controls on Organic Matter Accumulation of Marine Shale in the Ordovician Wulalike Formation, Northwestern Ordos Basin, China: Significance for Shale Gas Exploration |
| title_short | Quartz Origins and Paleoenvironmental Controls on Organic Matter Accumulation of Marine Shale in the Ordovician Wulalike Formation, Northwestern Ordos Basin, China: Significance for Shale Gas Exploration |
| title_sort | quartz origins and paleoenvironmental controls on organic matter accumulation of marine shale in the ordovician wulalike formation northwestern ordos basin china significance for shale gas exploration |
| topic | Ordos Basin Wulalike Formation biogenic quartz paleoenvironments organic matter accumulation |
| url | https://www.mdpi.com/1996-1073/16/14/5278 |
| work_keys_str_mv | AT yannizhang quartzoriginsandpaleoenvironmentalcontrolsonorganicmatteraccumulationofmarineshaleintheordovicianwulalikeformationnorthwesternordosbasinchinasignificanceforshalegasexploration AT rongxili quartzoriginsandpaleoenvironmentalcontrolsonorganicmatteraccumulationofmarineshaleintheordovicianwulalikeformationnorthwesternordosbasinchinasignificanceforshalegasexploration AT shenglixi quartzoriginsandpaleoenvironmentalcontrolsonorganicmatteraccumulationofmarineshaleintheordovicianwulalikeformationnorthwesternordosbasinchinasignificanceforshalegasexploration AT jianwengao quartzoriginsandpaleoenvironmentalcontrolsonorganicmatteraccumulationofmarineshaleintheordovicianwulalikeformationnorthwesternordosbasinchinasignificanceforshalegasexploration AT leichen quartzoriginsandpaleoenvironmentalcontrolsonorganicmatteraccumulationofmarineshaleintheordovicianwulalikeformationnorthwesternordosbasinchinasignificanceforshalegasexploration AT hexinhuang quartzoriginsandpaleoenvironmentalcontrolsonorganicmatteraccumulationofmarineshaleintheordovicianwulalikeformationnorthwesternordosbasinchinasignificanceforshalegasexploration AT bangshengzhao quartzoriginsandpaleoenvironmentalcontrolsonorganicmatteraccumulationofmarineshaleintheordovicianwulalikeformationnorthwesternordosbasinchinasignificanceforshalegasexploration AT ahmedkhaled quartzoriginsandpaleoenvironmentalcontrolsonorganicmatteraccumulationofmarineshaleintheordovicianwulalikeformationnorthwesternordosbasinchinasignificanceforshalegasexploration |