西藏崗巴西山晚白堊世—早古近紀(jì)有孔蟲生物地層
發(fā)布時(shí)間：2019-03-29 19:42
【摘要】：目前,我們對東特提斯西藏地區(qū)晚白堊世-早古近紀(jì)底棲大有孔蟲的認(rèn)識仍然較少。通過對西藏淺海沉積中的底棲大有孔蟲化石的分析和總結(jié),本論文初步建立了一整套較高精度的晚白堊-早古近紀(jì)的有孔蟲生物地層。(1)通過對西藏特提斯晚白堊紀(jì)世-早古近紀(jì)海相地層及其所含的底棲有孔蟲的研究,識別出四個(gè)沉積階段13個(gè)有孔蟲生物帶:(1)第一個(gè)沉積階段(Coniacian期到Maastrichtian期),大部分形成于較深的內(nèi)部-外部淺海環(huán)境,具有龍脊的浮游有孔蟲是這一階段動(dòng)物群(TLK1)的主要組成;(2)第二個(gè)沉積階段(Maastrichtian末期),浮游有孔蟲幾乎被礁前動(dòng)物群(主要以Lepidorbitoides、Omphalocyclus和Orbitoides種類為主,TLK2)完全替代;(3)第三個(gè)沉積階段(古新世早期),在白堊紀(jì)末期的全球性大滅絕之后,古新世時(shí)全球氣溫開始變暖,淺海礁體環(huán)境開始重新出現(xiàn),更適宜在溫暖淺海環(huán)境下生存的底棲大有孔蟲在這一時(shí)期非常繁盛,因此古新世的底棲動(dòng)物群主要有小個(gè)體miliolids和rotaliids底棲有孔蟲(如Ranikothalia、Daviesina和Lockhartia等,TP1-4);(4)第四個(gè)沉積階段(古新世晚期-始新世早期),淺海礁體環(huán)境主要由溫水底棲有孔蟲種類(如Alveolina及Assilina,TP5-11)為主。(2)結(jié)合前人研究提出的碳同位素偏移數(shù)據(jù)(CIE),在本文劃分的有孔蟲生物地層基礎(chǔ)上,將P-E界線確定在TP6中部位置,對應(yīng)著標(biāo)準(zhǔn)底棲有孔蟲化石帶5(SBZ5)上部位置,而不是其他學(xué)者認(rèn)為的SBZ4-SBZ5交界位置。(3)結(jié)合對東、西特提斯底棲大有孔蟲生物帶目前的研究成果,認(rèn)為Alveolina等底棲大有孔蟲在東特提斯的出現(xiàn)時(shí)間比西特提斯晚了大約1Ma,這也支持了底棲大有孔蟲由西向東遷移的推測。(4)本次研究重新建立了東特提斯晚白堊世-早古近紀(jì)底棲大有孔蟲生物地層序列,同時(shí)也在東特提斯生物帶與西特提斯淺海底棲生物帶(SBZs)之間建立了清晰的聯(lián)系。基于有孔蟲生物地層重新確定了崗巴西山剖面中的P-E界線。
[Abstract]:At present, our understanding of the late Cretaceous-early Paleogene benthic foraminifera in the Tibet area of East Tethys is still less than that of the late Cretaceous-early Paleogene foraminifera. Based on the analysis and summary of the benthic foraminifera fossils in the shallow sea sediments of Tibet, A set of high precision foraminifera biostratigraphy from late Cretaceous to early Paleogene has been established in this paper. (1) the marine strata and their benthic foraminifera contained in Tethys, Tibet, are studied in this paper. Thirteen foraminifera biota were identified in four sedimentary stages: (1) the first sedimentary stage (Coniacian to Maastrichtian), most of which was formed in a deeper inner-outer shallow sea environment; The zooplankton foraminifera with dragon ridges is the main component of the fauna (TLK1) at this stage. (2) in the second sedimentary stage (end of Maastrichtian), phytoplankton foraminifera was almost replaced by prereef fauna (mainly Lepidorbitoides,Omphalocyclus and Orbitoides species, TLK2). (3) in the third sedimentary stage (early Paleocene), after the global extinction at the end of the Cretaceous, the global temperature began to warm in the Paleocene, and the shallow reef environment began to re-emerge. Benthic foraminifera, which are more suitable for living in warm shallow sea environment, are very prosperous in this period. Therefore, the Paleocene benthic fauna mainly consists of miliolids and rotaliids benthic foraminifera (such as Ranikothalia,Daviesina and Lockhartia, TP1-4). (4) in the fourth sedimentary stage (late Paleocene-early Eocene), the shallow reef environment consists mainly of warm-water benthic foraminifera species (such as Alveolina and Assilina,). (2) on the basis of the foraminifera biostratigraphy in this paper, based on the carbon isotope migration data (CIE), the TP5-11 boundary is located in the middle part of the TP6. It corresponds to the upper position of the standard benthic foraminiferal fossil zone 5 (SBZ5) rather than the SBZ4-SBZ5 junction position considered by other scholars. (3) combined with the present research results of the macroforaminiferal benthic foraminifera belt in eastern and western Tethys, It is believed that the occurrence of benthic foraminifera such as Alveolina in East Tethys was about 1 Maa later than that of Seettis. This also supports the hypothesis that benthic large foraminifera migrate from west to east. (4) this study reestablished the late Cretaceous-early Paleogene macroforaminifera biostratigraphic sequence of East Tethys. A clear link has also been established between the East Tethys belt and the Seettis shallow benthic zone (SBZs). Based on the foraminifera biostratigraphy, the P _ (?) E boundary in the Gangbaishan profile has been redefined.
【學(xué)位授予單位】：中國地質(zhì)大學(xué)(北京)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：Q915
本文編號：2449824
[Abstract]:At present, our understanding of the late Cretaceous-early Paleogene benthic foraminifera in the Tibet area of East Tethys is still less than that of the late Cretaceous-early Paleogene foraminifera. Based on the analysis and summary of the benthic foraminifera fossils in the shallow sea sediments of Tibet, A set of high precision foraminifera biostratigraphy from late Cretaceous to early Paleogene has been established in this paper. (1) the marine strata and their benthic foraminifera contained in Tethys, Tibet, are studied in this paper. Thirteen foraminifera biota were identified in four sedimentary stages: (1) the first sedimentary stage (Coniacian to Maastrichtian), most of which was formed in a deeper inner-outer shallow sea environment; The zooplankton foraminifera with dragon ridges is the main component of the fauna (TLK1) at this stage. (2) in the second sedimentary stage (end of Maastrichtian), phytoplankton foraminifera was almost replaced by prereef fauna (mainly Lepidorbitoides,Omphalocyclus and Orbitoides species, TLK2). (3) in the third sedimentary stage (early Paleocene), after the global extinction at the end of the Cretaceous, the global temperature began to warm in the Paleocene, and the shallow reef environment began to re-emerge. Benthic foraminifera, which are more suitable for living in warm shallow sea environment, are very prosperous in this period. Therefore, the Paleocene benthic fauna mainly consists of miliolids and rotaliids benthic foraminifera (such as Ranikothalia,Daviesina and Lockhartia, TP1-4). (4) in the fourth sedimentary stage (late Paleocene-early Eocene), the shallow reef environment consists mainly of warm-water benthic foraminifera species (such as Alveolina and Assilina,). (2) on the basis of the foraminifera biostratigraphy in this paper, based on the carbon isotope migration data (CIE), the TP5-11 boundary is located in the middle part of the TP6. It corresponds to the upper position of the standard benthic foraminiferal fossil zone 5 (SBZ5) rather than the SBZ4-SBZ5 junction position considered by other scholars. (3) combined with the present research results of the macroforaminiferal benthic foraminifera belt in eastern and western Tethys, It is believed that the occurrence of benthic foraminifera such as Alveolina in East Tethys was about 1 Maa later than that of Seettis. This also supports the hypothesis that benthic large foraminifera migrate from west to east. (4) this study reestablished the late Cretaceous-early Paleogene macroforaminifera biostratigraphic sequence of East Tethys. A clear link has also been established between the East Tethys belt and the Seettis shallow benthic zone (SBZs). Based on the foraminifera biostratigraphy, the P _ (?) E boundary in the Gangbaishan profile has been redefined.
【學(xué)位授予單位】：中國地質(zhì)大學(xué)(北京)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：Q915
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