论文部分内容阅读
皖南地区震旦系蓝田组是新元古代冰期后形成的岩石地层 ,它的中下段以黑色页岩沉积为主 ,上段为白云质灰岩。黑色页岩段的分析结果表明 :底部有机碳同位素数值较低 (δ13 Corg平均值为 - 31.9‰ ) ,总有机碳(TOC)和总有机氮 (TON)含量处于较低值 ;在底部之上 ,有机碳同位素数值缓慢升高 (从靠近底部的 - 32 .6‰升至顶部的 - 2 8.3‰ ) ,而TOC和TON含量分别可达 17.7%和 2 .7‰。这一分析结果应归于冰后期在缺氧条件下大量有机质埋藏所致。可以推测 ,这种变化从一个侧面反映了新元古代全球性大冰期结束后气候变化和生物演化规律 :冰期结束之后 ,海洋中的低等浮游藻类的底栖藻类在温暖气候条件下得以繁盛 ,伴随着这些还原性有机碳的沉积并大量进入岩石圈中 ,藻类光合作用产生的氧气进入大气圈 ,可能正是由于有机碳的沉积导致的氧气含量升高促使了真核多细胞生物在此之后得到了大发展。蓝田组上段白云质灰岩分析结果表明 :有机碳同位素和无机碳同位素分别呈现出较强的负漂移 (δ13 Corg:- 2 6 .8‰— - 35 .3‰ ;δ13 Ccarb:- 8.5‰— - 10 .2‰ ) ,而总有机碳 (TOC)含量呈现明显降低趋势。这一变化趋势可能主要归之于沉积有机质的氧化作用。可以推测 ,随着新元古代全球性大冰期结束后气候变暖 ,海洋藻类?
The Sinian Lantian Formation in southern Anhui is a lithosphere formed after the Neoproterozoic glacial period. The middle and lower parts of the Lantian Formation are dominated by black shale deposits and the upper part is dolomitic limestone. The analysis results of black shale show that the bottom organic carbon isotope values are lower (δ13 Corg average is -31.9 ‰), total organic carbon (TOC) and total organic nitrogen (TON) content are lower; above the bottom , Organic carbon isotope values increased slowly (from -32.6 ‰ near the bottom to -2.33 ‰ at the top) while TOC and TON contents reached 17.7% and 2.7%, respectively. The results of this analysis should be attributed to the massive deposition of organic matter under anaerobic conditions in the late ice stage. It can be speculated that this change reflects, on one side, the laws of climate change and bio-evolution after the Great Proterozoic Great Ice Age: After the ice period, the benthic algae of the lower phytoplankton in the oceans flourished in warm climates, With the deposition of these reductive organic carbon and the massive influx into the lithosphere, the oxygen produced by photosynthesis by algae enters the atmosphere. It is probably due to the increase of oxygen content caused by the deposition of organic carbon that eukaryotic multicellular organisms are after Got big development. The analysis results of dolomitic limestone in the upper section of the Lantian Formation show that the organic carbon isotopes and inorganic carbon isotopes exhibit strong negative drift (δ13 Corg: -26.8% -335.3%, δ13Ccarb: -8.5% -0.3% - 10 .2 ‰), while the content of total organic carbon (TOC) showed a significant decrease. This trend may be mainly due to the oxidation of sedimentary organic matter. Can speculate that with the global warming of the Neoproterozoic Great Ice Age after the warming of marine algae?