地球科学与环境学报
地毬科學與環境學報
지구과학여배경학보
JOURNAL OF EARTH SCIENCES AND ENVIRONMENT
2015年
1期
76-84
,共9页
吉利明%梁晓飞%贺聪%吴远东
吉利明%樑曉飛%賀聰%吳遠東
길리명%량효비%하총%오원동
两环烷烃%延长组%烃源岩%生物标志物%三叠系%葡萄藻%西峰地区%鄂尔多斯盆地
兩環烷烴%延長組%烴源巖%生物標誌物%三疊繫%葡萄藻%西峰地區%鄂爾多斯盆地
량배완경%연장조%경원암%생물표지물%삼첩계%포도조%서봉지구%악이다사분지
bicyclic alkane%Yanchang Formation%source rock%biomarker%Triassic%Botryococcus braunii%Xifeng area%Ordos Basin
鄂尔多斯盆地西南部西峰地区三叠系延长组烃源岩检出丰富的两环烷烃,主要为 C12~C14和C15、C16两组两环烷烃。其相对丰度表现出3种源岩模式:①以低碳数两环烷烃为主,出现于长71和长81段非烃源岩;②两组两环烷烃都很丰富,出现于长73段富有机质烃源岩;③以高碳数两环烷烃为主,主要发现于长73段烃源岩,也见于长72和长81段。尽管长7段热演化程度基本一致,但补身烷异构化指数变化明显,表明补身烷重排不仅受热演化的影响,而且受有机质来源和沉积环境的控制。延长组烃源岩具有明显的高补身烷优势,反映了烃源岩的还原性沉积环境。烃源岩高丰度C15、C16两环烷烃的检出则指示该地区晚三叠世发育淡水湖泊。葡萄藻不仅是该地区中生界石油的重要母质来源,而且可能是这些两环类标志物的直接生源。
鄂爾多斯盆地西南部西峰地區三疊繫延長組烴源巖檢齣豐富的兩環烷烴,主要為 C12~C14和C15、C16兩組兩環烷烴。其相對豐度錶現齣3種源巖模式:①以低碳數兩環烷烴為主,齣現于長71和長81段非烴源巖;②兩組兩環烷烴都很豐富,齣現于長73段富有機質烴源巖;③以高碳數兩環烷烴為主,主要髮現于長73段烴源巖,也見于長72和長81段。儘管長7段熱縯化程度基本一緻,但補身烷異構化指數變化明顯,錶明補身烷重排不僅受熱縯化的影響,而且受有機質來源和沉積環境的控製。延長組烴源巖具有明顯的高補身烷優勢,反映瞭烴源巖的還原性沉積環境。烴源巖高豐度C15、C16兩環烷烴的檢齣則指示該地區晚三疊世髮育淡水湖泊。葡萄藻不僅是該地區中生界石油的重要母質來源,而且可能是這些兩環類標誌物的直接生源。
악이다사분지서남부서봉지구삼첩계연장조경원암검출봉부적량배완경,주요위 C12~C14화C15、C16량조량배완경。기상대봉도표현출3충원암모식:①이저탄수량배완경위주,출현우장71화장81단비경원암;②량조량배완경도흔봉부,출현우장73단부유궤질경원암;③이고탄수량배완경위주,주요발현우장73단경원암,야견우장72화장81단。진관장7단열연화정도기본일치,단보신완이구화지수변화명현,표명보신완중배불부수열연화적영향,이차수유궤질래원화침적배경적공제。연장조경원암구유명현적고보신완우세,반영료경원암적환원성침적배경。경원암고봉도C15、C16량배완경적검출칙지시해지구만삼첩세발육담수호박。포도조불부시해지구중생계석유적중요모질래원,이차가능시저사량배류표지물적직접생원。
A lot of bicyclic alkanes are detected from source rocks of Triassic Yanchang Formation in Xifeng area of southwestern Ordos Basin.They are two groups of bicyclic alkanes mainly including C12-C14 and C15 ,C16 .The relative abundances of the two groups have three kinds of source rock patterns:①there are mainly bicyclic alkanes with lower carbon number,which are detected from non-source rocks of Chang-71 and Chang-81 sections;②the two groups both are very rich,and are detected from organic-rich source rocks of Chang-73 section;③there are mainly bicyclic alkanes with higher carbon number,which are detected from source rocks of Chang-73 , Chang-72 and Chang-81 sections.Although the thermal evolutions of Chang-7 section are similar,the change of drimane isomerization index is significant,so that drimane rearrangement is effected not only by the thermal evolution,but also by the source of organic matter and the depositional environment.The source rocks of Yanchang Formation have an obvious advantage of homodrimane, so that the depositional environment is reductive. C15 , C16 bicyclic alkanes of source rocks with high abundance are detected in the area,indicating that freshwater lake develops in Late Triassic. Botryococcus braunii is an important parent material of Mesozoic oil in the area,and also may be the direct biological sources of these bicyclic biomarkers.