Full
XIA Fang,born in 1998,master degree candidate,majors in geological engineering. E-mail: 2635410100@qq.com.
Outline
The Middle Jurassic black rock series in the Qiangtang Basin serve as significant hydrocarbon source rocks due to their high organic matter contents. The Biluo Co section was chosen as the research target. Based on paleontological stratigraphy and by analyzing the total organic carbon(TOC)contents as well as variations in carbon and oxygen isotopes,this study discussed the spatio-temporal distribution patterns of carbon and oxygen isotopes from the black rock series of the Bathonian-Callovian stages(Middle Jurassic),and the characteristics of the paleoenvironment and paleoclimate during this period. Results show that the TOC contents range from 0 to 1.5%,δ13Corg,δ13Ccarb and δ18O values vary between-24‰ and-26‰,-4.819‰ and 2.323‰(mean values of-0.659‰),-13.96‰ and 0.66‰(mean values of-7.37‰),respectively. According to the global carbon isotope correlations,the negative inorganic carbon excursions in the early Bathonian is associated with the enhanced terrigenous input triggered by the Early-Middle Jurassic regression event. The positive shifts of δ13Ccarb from the Middle-Late Bathonian to the Early Callovian correspond to the event of a substantial surge in marine primary productivity. During the Callovian-Early Oxfordian,a widespread positive carbon isotopes anomalies and high TOC contents of shales occurred in regions such as the Qiangtang Basin,Saudi Arabia,Paris Basin,and Polish Carpathians,which shows that the organic-rich black rock series are closely related to large-scale marine transgressions and primarily driven by the increase in the burial flux of organic matters under the backdrop of global sea-level rise. Moreover,paleontological and petrological characteristics,and redox-sensitive proxies(e.g.,V/(V+Ni),V/Cr,Ni/Co ratios) suggest that the black rock series deposited in a relatively reducing sedimentary environments. This study highlights that the carbon and oxygen isotopes of Middle Jurassic black rock series have the global distribution patterns influenced by multiple factors,including redox conditions,sea-level fluctuations, burial dynamics of organic matters, and so on.
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| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |
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