CAJ | 학술논문

采用X射线衍射和扫描电子分析方法,对青海循化盆地晚渐新世沉积物的矿物组成、坡缕石的矿物学特征以及古气候指示作用进行了深入的研究.结果表明,晚渐新世循化盆地沉积物中粘土矿物组成主要有蒙脱石、伊利石、坡缕石和绿泥石等;坡缕石一般呈纤维状或者针状,沿片状蒙脱石的边缘及表面交代生长,为典型自生成因的坡缕石.坡缕石是干旱-半干旱气候条件的特征矿物,其出现表明循化地区晚渐新世气候特征较为干旱,与粘土矿物组合及伊利石结晶度所反映的气候环境信息相吻合;沉积物中坡缕石相对含量及有序度自下而上逐渐增大,说明循化地区的干旱化逐渐加剧.循化地区晚渐新世(～23 Ma)的干旱化可能与青藏高原隆升或者全球气候变冷事件密切相关.
채용X사선연사화소묘전자분석방법,대청해순화분지만점신세침적물적광물조성、파루석적광물학특정이급고기후지시작용진행료심입적연구.결과표명,만점신세순화분지침적물중점토광물조성주요유몽탈석、이리석、파루석화록니석등;파루석일반정섬유상혹자침상,연편상몽탈석적변연급표면교대생장,위전형자생성인적파루석.파루석시간한-반간한기후조건적특정광물,기출현표명순화지구만점신세기후특정교위간한,여점토광물조합급이리석결정도소반영적기후배경신식상문합;침적물중파루석상대함량급유서도자하이상축점증대,설명순화지구적간한화축점가극.순화지구만점신세(～23 Ma)적간한화가능여청장고원륭승혹자전구기후변랭사건밀절상관.
Mineral compositions and palaeoclimatic indicator of palygorskite of the Late Oligocene sediments in Xunhua basin, Qinghai,were investigated using X-ray diffraction (XRD) and scanning electron microscopy (SEM) methods. The results show that mineral compositions of the sediments are smectite, illite, palygorskite and chlorite, and the fibrous or acicular palygorskites are typically authigenic,which grew along the edges or the surfaces of platy smectite, respectively. Palygorskite is a characteristic clay mineral under semi-arid and arid climate conditions, the occurrence of palygorskite in the Late Oligocene sediments in Xunhua basin is indicative of an arid palaeoclimate condition, which is consistent with the clay mineral assemblage and illite crystallinity. The relative content and crystallinity of palygorskite show an continuous increase from the lower to the upper portion, reflecting the increasing aridity. The arid palaeoclimate probably resulted from the uplift of Qinghai-Tibet Plateau or the global cooling event.