地質(zhì)學(xué)

地質(zhì)學(xué)

來源出版物：SCIENCE CHINA Earth Sciences，2015，58（2）: 183-194聯(lián)系郵箱：LONG Hao，longhao@niglas.ac.cn

封面介紹：天然氣水合物廣泛發(fā)育于多年凍土區(qū)、大陸架邊緣的深海沉積物和深湖泊沉積物中，是一種能量密度高的非常規(guī)高效清潔能源.由于天然氣水合物性質(zhì)不穩(wěn)定且極易分解，在氣候轉(zhuǎn)暖情況下，多年凍土退化極易引起天然氣水合物分解釋放甲烷，將加劇北半球氣候轉(zhuǎn)暖和生態(tài)環(huán)境災(zāi)變.為了開發(fā)和利用多年凍土區(qū)天然氣水合物新能源，揭示天然氣水合物的氣候環(huán)境效應(yīng)，中國科學(xué)院寒區(qū)旱區(qū)環(huán)境與工程研究所吳青柏研究組通過實(shí)施鉆探計(jì)劃，尋找和發(fā)現(xiàn)青藏高原多年凍土區(qū)天然氣水合物賦存證據(jù)，探討多年凍土與天然氣水合物賦存的關(guān)系.該研究將為青藏高原天然氣水合物的開發(fā)和利用奠定基礎(chǔ)，同時(shí)也為我國海洋天然氣水合物未來開采提供理想的試驗(yàn)場所，對(duì)改變我國新能源結(jié)構(gòu)和國家能源政策具有非常重要的意義.封面顯示了2013年昆侖山埡口盆地天然氣水合物450 m孔鉆探現(xiàn)場.詳見吳青柏等人文（p68）.

青藏高原昆侖山埡口盆地發(fā)現(xiàn)天然氣水合物賦存的證據(jù)

吳青柏，蔣觀利，張鵬，等

青藏高原多年凍土區(qū)是否存在天然氣水合物一直是國內(nèi)外廣泛關(guān)注的問題，但一直沒有確定的答案.通過鉆探、地球物理測(cè)井以及氣體地球化學(xué)研究，在昆侖山埡口盆地發(fā)現(xiàn)了天然氣水合物賦存的證據(jù).鉆探發(fā)現(xiàn)250 m以下多個(gè)深度巖層存在大量氣體釋放異常，甲烷氣體濃度為22%～32%，且具有天然氣水合物分解間歇性釋放的特征，這些氣體釋放層位具有顯著的含天然氣水合物特有的密度降低、側(cè)向電阻率和聲波波速的增大特征.同時(shí)多個(gè)深度上發(fā)現(xiàn)了與水合物分解產(chǎn)生甲烷密切相關(guān)的碳酸鹽和黃鐵礦等自生礦物.

昆侖山埡口盆地；多年凍土；天然氣水合物；地球物理測(cè)井異常；氣體釋放

來源出版物：科學(xué)通報(bào)，2015，60（1）: 68-74聯(lián)系郵箱：吳青柏，qbwu@lzb.ac.cn

封面介紹：14C and OSL chronologies suggest a significant timing offset on late Pleistocene lake highstands across the Tibetan Plateau and adjacent areas. This results largely from14C age underestimation when the sediments being dated were older than ～30 ka. The mega-palaeolake，traditionally assigned to MIS 3a based on14C dating，is likely older than ～80 ka based on OSL chronology. For more details see the research paper by LONG Hao et al. on pages 183-194.

Underestimated14C-based chronology of late Pleistocene high lake-level events over the Tibetan Plateau and adjacent areas： Evidence from the Qaidam Basin and Tengger Desert

LONG Hao，SHEN Ji

The palaeolake evolution across the Tibetan Plateau and adjacent areas has been extensively studied，but the timing of late Pleistocene lake highstands remains controversial. Robust dating of lacustrine deposits is of importance in resolving this issue. This paper presents14C or optically stimulated luminescence（OSL）age estimates from two sets of late Quaternary lacustrine sequences in the Qaidam Basin and Tengger Desert（northeastern Tibetan Plateau）. The updated dating results show:（1）the radiocarbon dating technique apparently underestimated the age of the strata of ＞30 ka BP in Qaidam Basin；（2）although OSL and14C dating agreed with each other for Holocene age samples in the Tengger Desert area，there was a significant offset in dating results of sediments older than ～30 ka BP，largely resulting from radiocarbon dating underestimation；（3）both cases imply that most of the published radiocarbon ages（e.g.，older than ～30 ka BP）should be treated with caution and perhaps its geological implication should be revaluated； and（4）the high lake events on the Tibetan Plateau and adjacent areas，traditionally assigned to MIS 3a based on14C dating，are likely older than ～80 ka based on OSL chronology.

Tibetan Plateau； lake highstand； lacustrine sediments；14C dating； OSL dating