PDF
Full
Outline
Objective Carbonate-evaporite syngenetic systems are widely distributed in the Cambrian rocks of the Sichuan Basin. However， their development， depositional environments and processes and evolutionary modes have rarely been studied， and the research methods urgently need to be clarified. Methods The petrology and processes of the symbiotic system， the state of the evaporites， the depositional environment and the evolutionary pattern were investigated using drill core data， field sections， rock strata， C and O isotopes， Fe and Mn contents， and S isotopic composition. Neither the developmental characteristics of the symbiotic system and depositional environment nor its evolutionary pattern are well understood. Results （1） Five kinds of carbonate-evaporite symbiotic rock assemblages were found in the study area： interbedded carbonate rock and evaporite； evaporite sandwiched with carbonate rock； evaporite overlain by carbonate rock； carbonate rock overlain by evaporite rock； and carbonate rock sandwiched with evaporite rock. （2） The δ¹⁸O values ranged predominantly from -9.00‰ to -8.00‰， while δ¹³C values ranged between -1.00‰ and 3.00‰. Calculations of paleosalinity and paleotemperature using these isotope values gave the vast majority of Z>120 and δ13C>-2.00‰， with paleoseawater temperatures in the range 23.10 ℃-40.64 ℃. Fe was mainly concentrated in the range （0-2 000）×10-5， and Mn from 10-5 to 30×10-5. These indicate a warm or hot paleoclimate and saline seawater environment during deposition of the Gaotai Formation， with a high degree of oxidation in the water body， and the rock-forming activity occurring in a system relatively open to precipitation of atmospheric water. （3） Deposition of marine carbonate rocks and evaporites took place in a symbiotic system against a background of an arid， hot climate and a calcium-rich， low-sulfate， highly saline calcitic sea. This period of time witnessed two types of carbonatite-evaporite symbiotic development： A falling-sea-level evaporite-dolomite deposition stage （“tidal sabkha mode”）， and a rising-sea-level dolomite-evaporite-greywacke deposition stage （“underwater condensed-deposition mode”）. Conclusions The carbonatite-evaporite symbiotic system has recorded information about the paleoenvironment， paleoclimate and paleohaline water chemistry during the deposition period， as well as the depositional process and evolutionary pattern of the symbiotic system. This study provides new ideas and understandings of the depositional environments and patterns of the carbonatite-evaporite symbiotic system in the evaporitic environment of the marine phase of the developing Cambrian Gaotai Formation.
PDF
3
1
| 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 |
关闭全屏
No. 86 Xueyuan South Road, Haidian District, Beijing
010-62199257
qkjq@cast.org.cn
Copyright © 2025 China Association for Science and Technology. All rights reserved. For all open access content, the relevant licensing terms apply.
Sponsored by the Office of the Leading Group for Cybersecurity and Informatization of CAST, and supported by Science and Technology Review Publishing House
