發(fā)布時(shí)間：2018-05-07 23:21

  本文選題：埃迪卡拉紀(jì) + 黃陵隆起　； 參考：《中國(guó)地質(zhì)大學(xué)》2016年博士論文

【摘要】：埃迪卡拉紀(jì)是“雪球地球”崩解后和寒武紀(jì)生命大爆發(fā)之前,地球環(huán)境演變和生命演化的重要時(shí)期。華南埃迪卡拉紀(jì)地層中記錄了大量保存精美的多細(xì)胞藻類(lèi)和動(dòng)物胚胎化石,也記錄了大氣第二次增氧的證據(jù),是國(guó)際上研究埃迪卡拉紀(jì)的熱點(diǎn)地區(qū)之一。然而,生命活動(dòng)的各個(gè)化石記錄之間的對(duì)比和分布還存在爭(zhēng)議,記錄環(huán)境變化信息的地球化學(xué)信號(hào)也受控于海水的分層及其特殊的沉積環(huán)境。因此更加準(zhǔn)確的地層對(duì)比關(guān)系及沉積古地理格局對(duì)于理解埃迪卡拉紀(jì)生命的記錄和環(huán)境的演變,以及二者之間的關(guān)系具有重要意義。本文選取研究程度較高的黃陵隆起周緣為研究范圍,利用巖石地層、層序地層和化學(xué)地層等對(duì)比方法,來(lái)建立埃迪卡拉紀(jì)地層對(duì)比格架并恢復(fù)沉積古地理。根據(jù)地層發(fā)育特點(diǎn),本研究將黃陵隆起周緣地區(qū)進(jìn)一步細(xì)分為黃陵南緣、黃陵?yáng)|緣、黃陵北緣和黃陵西緣四個(gè)研究分區(qū),逐一展開(kāi)工作。首先,縱向上在各個(gè)研究分區(qū)分別建立地層對(duì)比格架;隨后,通過(guò)橫向上在整個(gè)研究區(qū)開(kāi)展關(guān)鍵層段的地層對(duì)比工作,建立整個(gè)研究區(qū)埃迪卡拉紀(jì)地層對(duì)比格架;最后,在新建立的地層對(duì)比格架基礎(chǔ)上,恢復(fù)埃迪卡拉紀(jì)不同階段的沉積古地理,并討論沉積古地理演變。黃陵南緣埃迪卡拉紀(jì)巖石地層包括陡山沱組和燈影組,其中陡山沱組劃分為四個(gè)巖性段,燈影組包括蛤蟆井段、石板灘段和白馬沱段,局部地區(qū)還劃分出廟河段和天柱山段；識(shí)別出六個(gè)層序界面,并可以在黃陵南緣進(jìn)行普遍對(duì)比；化學(xué)地層方面建立了完整而連續(xù)的埃迪卡拉紀(jì)碳同位素曲線(xiàn),識(shí)別出六次顯著的碳同位素負(fù)偏,并可以在黃陵南緣作為地層對(duì)比的重要標(biāo)志。在黃陵北緣將鉆孔剖面和露頭剖面結(jié)合起來(lái)開(kāi)展研究,重新厘定埃迪卡拉紀(jì)巖石地層,陡山沱組劃分為四個(gè)巖性段,其中陡山沱組第二段更是細(xì)分為四個(gè)亞段,燈影組自下而上劃分為蛤蟆井段、石板灘段和自馬沱段,上述巖石地層單元在黃陵北緣可以進(jìn)行很好的對(duì)比;在層序地層方面,識(shí)別出五個(gè)層序界面,并可以在黃陵北緣地區(qū)可以進(jìn)行對(duì)比；并對(duì)完整而連續(xù)的鉆孔剖面開(kāi)展碳同位素研究,建立起了黃陵北緣埃迪卡拉紀(jì)碳同位素變化曲線(xiàn),并識(shí)別出六次碳同位素異常。黃陵?yáng)|緣巖石地層包括陡山沱組和燈影組,其中陡山沱組劃分為四個(gè)巖性段,燈影組自下而上劃分出蛤蟆井段、石板灘段、自馬沱段和天柱山段四個(gè)巖性段；層序地層方面,識(shí)別出五個(gè)層序界面,并適用于黃陵?yáng)|緣地區(qū)；碳同位素研究集中陡山沱組上部至燈影組下部地層中,并在陡山沱組第三段頂部識(shí)別出一次明顯的碳同位素負(fù)偏。通過(guò)大量野外工作,在黃陵西緣也建立起了完整的埃迪卡拉紀(jì)地層序列,其巖石地層與層序地層與黃陵南緣基本一致。巖石地層包括陡山沱組和燈影組,其中陡山沱組劃分為四個(gè)巖性段,燈影組自下而上包括蛤蟆井段、廟河段、石板灘段和白馬沱段,廟河段僅在部分地區(qū)發(fā)育；層序地層方面,識(shí)別出六個(gè)層序界面。碳同位素研究主要集中在陡山沱組上部至燈影組石板灘段下部地層中,并在SB4和SB5附近發(fā)育兩次碳同位素負(fù)偏。為了將四個(gè)研究分區(qū)統(tǒng)一在一起,本文選取了關(guān)鍵層段的對(duì)比研究來(lái)實(shí)現(xiàn)整個(gè)埃迪卡拉紀(jì)地層對(duì)比。選取爭(zhēng)議較大的陡山沱組第四段和廟河段作為重點(diǎn)研究對(duì)象,通過(guò)層序地層、化學(xué)地層以及古生物化石的研究,將前人認(rèn)為是同一地層單元的廟河段與陡山沱組第四段分離開(kāi)來(lái)。提出并論證了廟河段層位要高于陡山沱組第四段,而與石板灘段下部地層相當(dāng)。據(jù)此,如果廟河段的項(xiàng)界年齡為551 Ma,那么陡山沱組第四段就要老于551 Ma,陡山沱組上部碳同位素負(fù)偏的結(jié)束年齡也要早于551 Ma,同時(shí)記錄在陡山沱組第四段中的海洋氧化事件也早于551 Ma。通過(guò)對(duì)不同區(qū)域陡山沱組第四段黑色頁(yè)巖和灰黑色薄層白云巖這兩種不同類(lèi)型巖性的層位討論,推斷黃陵?yáng)|緣和北緣可能不同程度的缺失了黃陵南緣和西緣層序3的地層。在前人開(kāi)展的埃迪卡拉紀(jì)(震旦紀(jì))年代地層劃分工作的基礎(chǔ)上,結(jié)合本文新提出的地層對(duì)比關(guān)系,以生物事件與環(huán)境事件的綜合特征為依據(jù),本文將黃陵周緣埃迪卡拉紀(jì)(震旦紀(jì))年代地層劃分為兩統(tǒng)四階。上下兩統(tǒng)的名稱(chēng)分別采用前人提出的峽東統(tǒng)和揚(yáng)子統(tǒng),本文對(duì)二者的界線(xiàn)進(jìn)行重新定義,并置于層序界面SB3,推定年齡為580 Ma。峽東統(tǒng)分為兩個(gè)階,第一階以發(fā)育微體化石組合的下組合為特征,其底界為陡山沱組蓋帽白云巖與南沱組冰磧巖的界線(xiàn),推定年齡為635 Ma；第二階以發(fā)育微體化石組合的上組合為特征,其底界以碳同位素負(fù)偏CN3的開(kāi)始為標(biāo)志,并伴隨著微體化石下組合的消失,推定年齡為610 Ma。揚(yáng)子統(tǒng)也分為兩個(gè)階,第三階無(wú)生物化石記錄,以發(fā)育顯著的碳同位素負(fù)偏為特征,其底界即為揚(yáng)子統(tǒng)的底界；第四階以發(fā)育宏體多細(xì)胞藻類(lèi)和后生動(dòng)物化石為特征,底界以廟河生物群的始現(xiàn)為標(biāo)志,并伴隨有碳同位素負(fù)偏,推定年齡為560 Ma。本文在年代地層的基礎(chǔ)上,以階為單位來(lái)討論各個(gè)時(shí)期的沉積古地理,同時(shí)根據(jù)各個(gè)時(shí)期內(nèi)古地理的變化再細(xì)分出不同的階段。其中第一期分為五個(gè)階段,第二期分為兩個(gè)階段,第三期分為三個(gè)階段,第四期分為三個(gè)階段。總共恢復(fù)了黃陵及周緣地區(qū)埃迪卡拉紀(jì)13個(gè)不同沉積階段的古地理。指出黃陵周緣埃迪卡拉紀(jì)沉積古地理比先前學(xué)者工作所反映的面貌的更為復(fù)雜,在空間上呈現(xiàn)西南低東北高的古地理格局；在時(shí)間上自從蓋帽白云巖結(jié)束后黃陵隆起周緣開(kāi)始進(jìn)入局限的環(huán)境中,直到～551 Ma之后才不再出現(xiàn)局限的環(huán)境。綜上,本文建立了黃陵隆起周緣埃迪卡拉紀(jì)地層對(duì)比格架,并恢復(fù)的不同時(shí)期的沉積古地理,為探討埃迪卡拉紀(jì)生命與環(huán)境的演化關(guān)系提供了重要的科學(xué)依據(jù)。
[Abstract]:According to the characteristics of strata development , this paper further divides the peripheral area of Huangling uplift into four sub - zones : the southern margin of Huangling , the eastern margin of Huangling , the northern margin of Huangling and the western margin of Huangling .
Six sequence interfaces are identified and can be compared in the southern margin of Huangling ;
In the northern margin of the Huangling , the drilling section and the open - head section are divided into four sub - segments , and the second segment of the Doushantuo Formation is divided into four sub - segments . The second segment of the Doushantuo Formation is divided into four sub - segments .
In this paper , a carbon isotope study was carried out on the complete and continuous borehole profile , and six carbon isotope anomalies were identified . Six carbon isotope anomalies were identified . The eastern margin of Huangling was divided into four lithologic segments , and the Dengying Formation divided into four lithologic segments from bottom to top .
In the area of sequence stratigraphy , five sequence interfaces are identified and applied to the eastern edge of Huangling ;
Carbon isotope studies have focused on the upper part of the Doushantuo Formation to the lower strata of the Dengying Formation and identified a clear carbon isotope negative deviation at the top of the third section of the Doushantuo Formation .
In order to unify the four research zones , the fourth section of the Doushantuo Formation and the fourth section of the Doushantuo Formation are divided into two orders .
The second order is characterized by the upper combination of the developmental microfossil assemblage , the bottom boundary of which is marked by the beginning of the carbon isotope negative deviation CN3 , and the presumed age is 610 Ma . The Yangtze is also divided into two orders , the third order has no biological fossil record , and is characterized by a significant carbon isotope negative bias , and the bottom boundary is the bottom boundary of the Yangtze .
The fourth order is characterized by the development of macro - organism multi - cell algae and metazolized animal fossils . The bottom boundary is marked by the beginning of the biological group of the temple and is accompanied by the negative bias of the carbon isotope , and the estimated age is 560 Ma . In the first part , the paleogeography of the 13 different sedimentary stages of the Ediacaran in Huangling and the peripheral area is divided into three stages .
During the time since the end of the cap - cap dolomite , the margin of Huangling uplift began to enter the confined environment , until ~ 551 Ma , and the confined environment ceased .

【學(xué)位授予單位】：中國(guó)地質(zhì)大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2016
【分類(lèi)號(hào)】：P531;P534.4

【參考文獻(xiàn)】

相關(guān)期刊論文 前3條

1 解古巍;周傳明;McFadden K A;肖書(shū)海;袁訓(xùn)來(lái);;湖北峽東地區(qū)九龍灣剖面震旦系陡山沱組微體化石的新發(fā)現(xiàn)[J];古生物學(xué)報(bào);2008年03期

2 ;Octoradiate Spiral Organisms in the Ediacaran of South China[J];Acta Geologica Sinica(English Edition);2008年01期

3 陳孝紅,李華芹,陳立德,王傳尚,汪嘯風(fēng);三峽地區(qū)震旦系碳酸鹽巖碳氧同位素特征[J];地質(zhì)論評(píng);2003年01期

，

本文編號(hào)：1858923