中国地质
中國地質
중국지질
CHINESE GEOLOGY
2014年
5期
1724-1734
,共11页
构造抬升%气候干旱化%江尕勒萨依%中亚%中中新世
構造抬升%氣候榦旱化%江尕勒薩依%中亞%中中新世
구조태승%기후간한화%강소륵살의%중아%중중신세
tectonic uplift%climatic aridity%Janggalsay%Central Asia%middle Miocene
提中亚前陆盆地地层中氧同位素和孢粉，以及黄土高原和北太平洋粉尘记录均表明，中中新世(16~12 Ma)中亚地区气候干旱化显著增强。然而，对其驱动机制的认识不一，包括全球降温、中亚地区的构造抬升、高海拔的“原西藏高原”的存在、副特提斯洋的退缩以及上述几者联合作用的结果。不过，全球降温(约14 Ma)、“原西藏高原”的抬升(≥40 Ma)、以及副特提斯洋退缩的时间(＞34 Ma)与中中新世中亚气候干旱化增强的时间(16~12 Ma)不一致。因此，它们可能是导致中中新世中亚干旱化增强的重要边界条件，或者是有利的辅助条件，但没起直接的主导作用。对塔里木盆地东南缘江尕勒萨伊剖面的前期研究结果表明，阿尔金山快速抬升始于16 Ma。在获得了磁性地层年龄的基础上，前人的碳氧同位素数据指示了16 Ma江尕勒萨依地区气候干旱化逐渐增强。鉴于同时发生，笔者把16 Ma气候干旱化增强归因于此时阿尔金山的快速抬升。从更广范围看，中中新世中亚发生了广泛的的地壳缩短变形和造山运动。对中国黄土高原的红粘土以及北太平洋粉尘沉积的多指标分析（磁化率、粒径、粉尘通量以及物源等）表明，中中新世中亚构造抬升及其引起的雨影效应是中亚气候干旱化增强的主因。
提中亞前陸盆地地層中氧同位素和孢粉，以及黃土高原和北太平洋粉塵記錄均錶明，中中新世(16~12 Ma)中亞地區氣候榦旱化顯著增彊。然而，對其驅動機製的認識不一，包括全毬降溫、中亞地區的構造抬升、高海拔的“原西藏高原”的存在、副特提斯洋的退縮以及上述幾者聯閤作用的結果。不過，全毬降溫(約14 Ma)、“原西藏高原”的抬升(≥40 Ma)、以及副特提斯洋退縮的時間(＞34 Ma)與中中新世中亞氣候榦旱化增彊的時間(16~12 Ma)不一緻。因此，它們可能是導緻中中新世中亞榦旱化增彊的重要邊界條件，或者是有利的輔助條件，但沒起直接的主導作用。對塔裏木盆地東南緣江尕勒薩伊剖麵的前期研究結果錶明，阿爾金山快速抬升始于16 Ma。在穫得瞭磁性地層年齡的基礎上，前人的碳氧同位素數據指示瞭16 Ma江尕勒薩依地區氣候榦旱化逐漸增彊。鑒于同時髮生，筆者把16 Ma氣候榦旱化增彊歸因于此時阿爾金山的快速抬升。從更廣範圍看，中中新世中亞髮生瞭廣汎的的地殼縮短變形和造山運動。對中國黃土高原的紅粘土以及北太平洋粉塵沉積的多指標分析（磁化率、粒徑、粉塵通量以及物源等）錶明，中中新世中亞構造抬升及其引起的雨影效應是中亞氣候榦旱化增彊的主因。
제중아전륙분지지층중양동위소화포분，이급황토고원화북태평양분진기록균표명，중중신세(16~12 Ma)중아지구기후간한화현저증강。연이，대기구동궤제적인식불일，포괄전구강온、중아지구적구조태승、고해발적“원서장고원”적존재、부특제사양적퇴축이급상술궤자연합작용적결과。불과，전구강온(약14 Ma)、“원서장고원”적태승(≥40 Ma)、이급부특제사양퇴축적시간(＞34 Ma)여중중신세중아기후간한화증강적시간(16~12 Ma)불일치。인차，타문가능시도치중중신세중아간한화증강적중요변계조건，혹자시유리적보조조건，단몰기직접적주도작용。대탑리목분지동남연강소륵살이부면적전기연구결과표명，아이금산쾌속태승시우16 Ma。재획득료자성지층년령적기출상，전인적탄양동위소수거지시료16 Ma강소륵살의지구기후간한화축점증강。감우동시발생，필자파16 Ma기후간한화증강귀인우차시아이금산적쾌속태승。종경엄범위간，중중신세중아발생료엄범적적지각축단변형화조산운동。대중국황토고원적홍점토이급북태평양분진침적적다지표분석（자화솔、립경、분진통량이급물원등）표명，중중신세중아구조태승급기인기적우영효응시중아기후간한화증강적주인。
Numerous studies suggest an intensification of climatic aridity during the middle Miocene (16-12 Ma) based on oxygen isotopes and pollen records in the foreland basins of the Central Asia, eolian deposits in China’s loess plateau and eolian flux from the northern Pacific Ocean. However, controversies remain existent as to the driving mechanisms that have dominated the intensifying aridity, which include global cooling, the rapid uplift of the central Asia, the attainment of a threshold elevation in southern Tibetan Plateau and the retreat of the Paratethys from the central Asia. As the timing of intensification of climatic aridity (16-12 Ma) is inconsistent with the onset age of global cooling (about 14 Ma), that of the attainment of a threshold elevation in the southern Tibetan Plateau (≥40 Ma), and that of the retreat of the Paratethys from the central Asia (>34 Ma), the authors hold that these three factors may be only important boundary conditions or favorable auxiliary conditions for the intensification of aridity during the middle Miocene. Previous studies of the Janggalsay strata on the southeast margin of the Tarim Basin indicated that the rapid uplift of the Altun Mountains occurred at~16 Ma. Combined with new magnetostratigraphic ages, the published carbon and oxygen isotopes data suggest a gradual intensification of climatic aridity since ~16 Ma for the Janggalsay area. Based on the simultaneous relationship, the authors attribute the middle Miocene increasing aridity to the rapid uplift of the Altun Mountains. Viewed from a broader context, the Mid-Miocene crustal shortening deformation is extensively existent within Central Asia. The multi-proxy analysis of red clay in China’s loess plateau and eolian dust from the northern Pacific Ocean indicates that the middle Miocene tectonic uplift and accompanying rain shadow effect acted as the major mechanism in driving the increased aridity in Central Asia.
