本文選題：原生白云石 + 微生物成因�。� 參考：《古地理學(xué)報(bào)》2017年02期

【摘要】：近年來,隨著對微生物白云石模式研究的不斷深入,為解釋"白云石問題"提供了新思路。前人對微生物白云石成因研究側(cè)重于微生物對未固結(jié)沉積物的改造,即有機(jī)準(zhǔn)同生白云石化作用,這與實(shí)驗(yàn)室中以微生物為媒介形成的"有機(jī)原生白云石"在成因機(jī)理上存在差異。筆者將微生物白云石機(jī)理引入湖相原生白云石成因解釋中,認(rèn)為在湖水—沉積物交界處也會發(fā)生微生物成因的原生白云石沉淀,即有機(jī)原生白云石。湖水與沉積物交界處的微環(huán)境存在明顯區(qū)別,總體可分為有氧和缺氧2種亞環(huán)境,不同亞環(huán)境中生活有不同的微生物群落。根據(jù)湖泊亞環(huán)境特性和微生物種類及其在白云石形成過程中所發(fā)揮的作用,可以區(qū)分出細(xì)菌有氧氧化模式、硫酸鹽還原模式和產(chǎn)甲烷模式3種微生物白云石模式。不同模式對應(yīng)于不同的湖泊環(huán)境:細(xì)菌有氧氧化模式主要發(fā)生于有氧、高M(jìn)g/Ca值的咸水/鹽湖環(huán)境;硫酸鹽還原模式主要發(fā)生于缺氧、高M(jìn)g/Ca值的咸水/鹽湖環(huán)境;產(chǎn)甲烷模式主要發(fā)生于缺氧、低Mg/Ca值的淡水/咸水湖環(huán)境。另外,還探討了pH值變化、SO_4~(2-)的存在和硫化物對鎂水合物脫水的影響以及微生物白云石沉淀的環(huán)境因子。對微生物成因的原生白云石模式的深入認(rèn)識,將為湖相白云石成因研究提供新的理論基礎(chǔ)和研究思路。
[Abstract]:In recent years, with the development of microorganism dolomite model, it provides a new way to explain dolomite problem. Previous studies on the genesis of microbial dolomite focus on the transformation of unconsolidated sediments by microbes, i.e., organic quasi-syngeneic dolomitization, This is different from the organic primary dolomite formed by microorganism in laboratory. The mechanism of microorganism dolomite is introduced into the explanation of the origin of lacustrine primary dolomite, and it is considered that the primary dolomite precipitate of microbial origin will also occur at the boundary between lake water and sediment, that is, organic primary dolomite. The microenvironment at the junction of lake water and sediment is obviously different. It can be divided into two subenvironments: aerobic and anoxic. There are different microbial communities in different subenvironments. According to the subenvironmental characteristics of the lake and the types of microbes and their role in the formation of dolomite, three microbial dolomite models can be distinguished: aerobic oxidation model, sulfate reduction model and methanogenic model. Different models correspond to different lake environments: bacterial aerobic oxidation occurs mainly in aerobic, salt water / salt lake environment with high Mg/Ca value, sulfate reduction model mainly occurs in salt water / salt lake environment with anoxic and high Mg/Ca values. Methanogenic patterns mainly occur in freshwater / salt lake environments with low Mg/Ca and hypoxia. In addition, the existence of pH value and the effect of sulfides on the dehydration of magnesium hydrate and the environmental factors of microbial dolomite precipitation were also discussed. A deep understanding of the primary dolomite model of microbial origin will provide a new theoretical basis and research idea for the study of lacustrine dolomite genesis.
【作者單位】： 北京大學(xué)地球與空間科學(xué)學(xué)院/石油與天然氣研究中心;中國地質(zhì)大學(xué)(北京)地球科學(xué)與資源學(xué)院;
【基金】：國家自然科學(xué)基金項(xiàng)目(批準(zhǔn)號:41572117)資助~~
【分類號】：P578.6

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