CAJ | 학술논문

应用化石硅藻属组合和属系数两个新指标对西藏南部昂仁湖(29°18′N，87°11′E)剖面硅藻记录进行解析，得出该地区在11000－6000 aBP间经历了寒冷期(11095－9 970 aBP)→温和期(9 970－9 870 aBP)→升温期 (9 870－9 770 aBP)→凉干期(9 770－8 740 aBP)→超高温期(8 740－8 590aBP)→高温期(8 590-5 970 aBP)的演变序列。同时发现在寒冷期存在增温(10 710 aBP)和降温(10 430 aBP)波动；凉干期8 800一8 760 aBP附近存在强低温事件；超高温期中的最高温出现在8 680 aBP附近；在高温期8000－7 920 aBP和7 170－7 090 aBP两个小时段分别存在增降温波动。在6 430 aBP附近存在明显的旱化现象。同时发现在研究时期除了存在1 000年的气候变化周期外还存在150－200年左右的气候转型期。昂仁湖发育则至少经历了缓慢扩张(1 1000－8 740 aBP)→快速扩张(8 740－8 590 aBP)→缓慢退缩(8 590－5 970 aBP)3个大阶段。也因此验证化石硅藻属组合和属系数两个新指标至少在富含硅藻的封闭湖盆环境演变研究中的有效性和便捷性。
응용화석규조속조합화속계수량개신지표대서장남부앙인호(29°18′N，87°11′E)부면규조기록진행해 석，득출해지구재11000－6000 aBP간경력료한랭기(11095－9 970 aBP)→온화기(9 970－9 870 aBP)→승온기 (9 870－9 770 aBP)→량간기(9 770－8 740 aBP)→초고온기(8 740－8 590aBP)→고온기(8 590-5 970 aBP)적연 변서렬。동시발현재한랭기존재증온(10 710 aBP)화강온(10 430 aBP)파동；량간기8 800일8 760 aBP부근존재강 저온사건；초고온기중적최고온출현재8 680 aBP부근；재고온기8000－7 920 aBP화7 170－7 090 aBP량개소시 단분별존재증강온파동。재6 430 aBP부근존재명현적한화현상。동시발현재연구시기제료존재1 000년적기후 변화주기외환존재150－200년좌우적기후전형기。앙인호발육칙지소경력료완만확장(1 1000－8 740 aBP)→쾌 속확장(8 740－8 590 aBP)→완만퇴축(8 590－5 970 aBP)3개대계단。야인차험증화석규조속조합화속계수량개 신지표지소재부함규조적봉폐호분배경연변연구중적유효성화편첩성。
Based on the analysis of diatom record in An gren, southern Xizang by using new indexes of diatom genus spectrum and ratio of genus/species, the cli matic sequence between 11 000aBP and 6 000aBP at that area is established, that is: cold period ( 11 095－9 970 aBP) → temperate period ( 9 970－ 9 870 aBP) →anathermal (9 870－9 770 aBP) → cool-dry period (9 770－8 740 aBP)→super-megath ermal (8 740－8 590 aBP) →megathermal (8 590－ 5 970 aBP). And some climatic fluctuations or oscil lations in the period are found, those are: (1) low temperature at 10 710aBP and high temperature at 10 430 aBP in Younger Dryas, (2) an abrupt drop of temperature between 8 800－8 760 aBP in the cool dry period, (3) occurrence of the highest temperature at about 8 680 aBP in the super-megathermal, (4) the pulses of high and low temperature in the megath ermal respectively in 8 000－7 920 aBP and 7 170－ 7 090 aBP, and (5) obvious dryness at 6 430 aBP in the mid-Holocene. Apart from climatic periodicity of 1 000 years, the transitional period of climatic changes with 150－200 years between 11 000－6 000 aBP is found too. Furthermore, the development of Angren Lake between 11 000－6 000 aBP underwent three main stages of gradual expansion (11 095－ 8 740 aBP), abrupt expansion (8 740－8 590 aBP) and gradual shrinkage (8 590－5 970 aBP). More over, the results also show that the new diatom in dexes are effective and convenient at least in studying environmental changes in closet lacustrine basin, which is rich in fossil diatoms.