本文關(guān)鍵詞： 改則盆地 康托組 碳氧同位素 晚始新世干旱 青藏高原隆升　出處：《地質(zhì)學(xué)報》2016年08期 　論文類型：期刊論文

【摘要】：改則盆地位于青藏高原腹地,盆地內(nèi)沉積物記錄了高原古環(huán)境變化的重要信息。本文對改則盆地康托組碳酸鹽巖碳氧同位素進(jìn)行研究,結(jié)果顯示改則盆地中-晚始新世的演化分為兩個階段:1中始新世濕潤氣候下開放湖盆階段:雖然碳酸鹽巖δ~(18)O值在43層處向正值偏移,但整體~(18)O和~(13)C強(qiáng)烈虧損,并且該時期碳酸鹽巖δ~(18)O值和δ~(13)C變化相關(guān)系數(shù)為R~2=0.082。表明該階段的研究區(qū)雖然經(jīng)歷過短期蒸發(fā)作用增強(qiáng)或補給水減少,但整體是氣候濕潤條件下補給水豐富的開放型湖盆。2晚始新世干旱氣候下封閉湖盆階段:經(jīng)過中新世晚期(63層)氣候和湖泊水文狀態(tài)的過渡,晚始新世~(18)O和~(13)C同位素富集,δ~(18)O值和δ~(13)C值變化相關(guān)系數(shù)為R~2=0.7762。表明該階段氣候干旱,蒸發(fā)作用強(qiáng)烈,湖盆萎縮成為封閉湖盆。綜合前人研究,認(rèn)為青藏高原腹地及北緣、東北緣在晚始新世存在明顯的區(qū)域性干旱化事件。對比分析青藏高原隆升、全球氣候記錄、全球海水Sr和大氣CO_2記錄,認(rèn)為青藏高原腹地和北部的干旱化事件主要受青藏高原隆升的影響。
[Abstract]:The basin is located in the hinterland of the Qinghai-Tibet Plateau and the sediments in the basin record the important information of paleoenvironmental changes in the plateau. The results show that the evolution of the modified basin can be divided into two stages: the open lacustrine basin stage under the humid climate of Miocene: although the 未 ~ (18) O value of carbonate rocks shifts positively at the 43rd layer. Overall, however, there were significant losses. And the 未 ~ (18) O value and 未 ~ (13)) of carbonate rocks in this period. The correlation coefficient of the change of C is Ru _ 2N _ (0.082), which indicates that the study area in this stage has experienced a short period of evaporation enhancement or a decrease in recharge water. But the whole is the transition of the open lake basin with abundant recharge water under humid climate. 2. The closed lake basin stage under the late Eocene arid climate: through the late Miocene (63 layers) climate and the lake hydrological state. The late Eocene ~ (18) O and ~ (13) ~ (13) C isotopes were enriched, and the correlation coefficients of 未 ~ (18) ~ (18) O and 未 ~ (13) ~ (13) ~ C values were R ~ (2 +) ~ 0. 776 ~ (2), indicating that the climate was dry in this stage. The evaporation is strong and the lake basin shrinks into a closed lake basin. Based on previous studies, it is considered that there are obvious regional drought events in the hinterland, northern margin and northeast margin of the Qinghai-Tibet Plateau in the late Eocene. The uplift of the Qinghai-Xizang Plateau is comparatively analyzed. Global climate records, sea water Sr and atmospheric CO_2 records indicate that drought events in the hinterland and north of the Qinghai-Xizang Plateau are mainly affected by the uplift of the Qinghai-Xizang Plateau.
【作者單位】： 中國地質(zhì)科學(xué)院水文地質(zhì)環(huán)境地質(zhì)研究所;中國地質(zhì)大學(xué)地球科學(xué)學(xué)院;中國地質(zhì)大學(xué)生物地質(zhì)與環(huán)境地質(zhì)國家重點實驗室;中國地質(zhì)大學(xué)地質(zhì)調(diào)查研究院;中國地質(zhì)調(diào)查局成都地質(zhì)調(diào)查中心;
【基金】：中國地質(zhì)調(diào)查局青藏專項項目(編號:1212011121261)資助的成果
【分類號】：P532;P597
【正文快照】： 新生代以來,地球由全球無冰的“溫室”狀態(tài),逐漸轉(zhuǎn)變?yōu)楝F(xiàn)今兩級發(fā)育大冰蓋的“冰室”狀態(tài)(Zoach et al.,2001)。期間,青藏高原的隆升不僅影響著亞洲季風(fēng)-干旱氣候的格局(An Zhishenget al.,2001;Guo Zhengtang et al.,2002;Liu Xiaodong et al.,2013;Zhang Chunxia et al.,201

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