龙门山造山带-川西前陆盆地系统构造事件研究

通过对构造事件形成的产物 (岩浆岩、各种矿物等 )进行氩 -氩年龄测定、裂变径迹年龄测定、ESR年龄测定和计算机模拟 ,得出龙门山造山带 -川西前陆盆地系统自印支期以来 ,共发生了 7次构造事件 :(1)卡尼期末的构造事件 (D1 ) ,形成 S1 和 F1 ,并有区域低温动热变质作用 ;(2 )诺利期末的构造事件 (安县运动 ,D2 ) ,产生川西前陆盆地上三叠统须四段与下伏地层不整合接触和须四段砾岩的分布 ,并有较强的岩浆作用 ;(3)燕山期 (12 0～ 130 Ma,D3) ,有较强的岩浆作用和变质作用 ;(4 )喜马拉雅期 6 0 Ma左右的构造事件 (D4) ;(5 )喜马拉雅期 30～ 40Ma的构造事件 (D5 ) ;(6 )喜马拉雅期 2 0～ 2 5 Ma的构造事件 (D6 ) ;(7)喜马拉雅期 10 Ma的构造事件 (D7)。后 4次构造事件使龙门山造山带 -川西前陆盆地系统发生强烈的冲断作用和隆升作用     

Re-Os isotopic system and formation age of subcontinental lithosphere mantle

The determination of the formation age of subcontinental Lithosphere Mantle (SCLM) is a widely concerned issue in mantle geochemistry. It is difficult to obtain the formation age of SCLM using lithophile isotopic systems such as Rb-Sr, Sm-Nd, U-Th-Pb, etc., but as siderophile elements, the Re-Os isotopic system provides a powerful tool for that work. Here a comprehensive review on the recent development in Re-Os dating for SCLM has been given.     

吐哈盆地鄯善油田油气运聚期次及成藏过程研究

吐哈盆地鄯善油田储层流体包裹体明显分为盐水包裹体和有机包裹体。三间房组包裹体均一化温度明显分为两期 ,其对应的地质时间分别为早白垩世和早第三纪末—晚第三纪 ;西山窑组储层流体包裹体均一化温度也明显分为两期 ,其对应的地质时间分别为晚侏罗世—早白垩世和晚白垩世末—早第三纪。鄯善油田西山窑组和三间房组储层自生伊利石同位素年龄分别为 32 .8～ 71.8Ma和 2 6 .4～ 45 .7Ma ,其对应的地史时期分别为早第三纪和晚白垩世末—早第三纪中期 ,反映了三间房组成藏时间晚于西山窑组成藏时间。综合分析油气生排烃史和运聚期次 ,鄯善油田油气大规模运聚时间是在晚白垩纪末—早第三纪及其以后 ,具有双侧近源晚期成藏的特点     

Precise timing of lacustrine gypsum in Luobubo, Xinjiang using the thermal ionization mass spectrometry U-series method

Dating techniques including gypsum dissolution in water, iron hydroxide co-precipitation with uranium and thorium and mass spectrometric determination have been investigated in this note. The ages of the gypsum samples in a CK core from Luobubo lacustrine sediments are in the range of (12.85±0.21) kaBP (4 m distance from the top core) to (153.2±7.2) kaBP (49 m distance from the top core) with the relative errors of ±1.6%–±4.7%. It indicates that the sedimental environment of the CK core was situated in the middle-late Pleistocene and Holocene periods, corresponding to 1–6 stages of oxygen isotopes in the abyssal sediments and included much information from last interglacial to Holocene warm periods.     

Fine grain IRSL and GLSL dating of late Quaternary sediments from North China

A possible approach to assess the fine grain OSL dating is discussed through comparison of equivalent dose (D_E) values and ages obtained by IRSL and GLSL of fine grains for 31 sediment samples from North China. The IRSL and GLSL were measured with the same aliquots for each sample, i.e. shine-down was by 100 s of IRSL (880 nm) followed by 100 s of GLSL (514 nm) on the same discs. The D_E values and ages found by IRSL are in good agreement with those by GLSL within 1—2σ for 80% samples, especially for aeolian loess samples. Considering that IRSL from feldspar differs obviously from GLSL dominated from quartz in dose response, thermal stability and optical bleaching characteristic, the agreement between the D_E values may be taken as evidence that the two clocks of IRSL and GLSL had been well reset during deposition. The consistent ages of IRSL and GLSL, in turn, may be referred to an indicator to evaluate the fine grain OSL dating of sediments.     

火山岩样品的预处理及其对K-Ar年龄值的矫正

K-Ar和Ar-Ar法是中、新生代火山岩最有效的测年方法之一,合适的粒度和有效的预处理程序对于提高年龄资料的质量至关重要。样品粒度选用60～80目粒级（0.28～0.18mm）既能保证样品的均匀性,又可以有效去除大气氩的污染。新鲜火山岩需要用稀硝酸浸泡,以去除可能的碳酸盐的影响;轻微蚀变的火山岩则须用6%氢氟酸浸泡5 min,对年龄值的矫正可达20%。用电磁选的方法可以在很大程度上剔除捕虏晶的影响,对年龄值的矫正可达5%～10%。     

闽江河口第四纪地层划分和地质年代研究

本文系统地研究了闽江河口琅岐岛钻孔揭示的第四纪地层。根据孢粉、微古、硅藻和~(14)C测年等资料分析了沉积物形成时的气候波动、沉积相和沉积物年代,将闽江河口第四纪地层划分为上更新统上段(厚>15米)和全新统(厚49.80米)。全新统又可分为下全新统下段和上段、中全新统和上全新统。气候演化为:冷干→温暖略干→温暖湿润→炎热潮湿→温暖略干。沉积相演化为:冲积相、冲洪积相、湖沼相→冲积相、湖沼相→河口相、湖沼相→海湾相→河口相。     

闽江河口第四纪地层划分和地质年代研究

本文系统地研究了闽江河口琅岐岛钻孔揭示的第四纪地层。根据孢粉、微古、硅藻和~(14)C测年等资料分析了沉积物形成时的气候波动、沉积相和沉积物年代,将闽江河口第四纪地层划分为上更新统上段(厚>15米)和全新统(厚49.80米)。全新统又可分为下全新统下段和上段、中全新统和上全新统。气候演化为:冷干→温暖略干→温暖湿润→炎热潮湿→温暖略干。沉积相演化为:冲积相、冲洪积相、湖沼相→冲积相、湖沼相→河口相、湖沼相→海湾相→河口相。     

Comments on the planation surface once more

The authors reviewed the research of planation surface in recent years and commented on the development of method and theory about the planation surface. Some aspects of research, such as the restrictive planation surface, the karst planation surface, the fossil planation surface, the dating of weathering crust, the research of weathering crust and environmental evolution, extremely enriched the method and theory of the planation surface. Besides, the authors pointed out that we must take further steps to study the following issues: the deformation of planation surface, the original height of planation surface, the recognition and contrast of the planation surface. The weathering crust and planation surface should be regarded as a whole, and it will still be a principal aspect in the future.     

Timing of Holocene sea-level highstands by mass spectrometric U-series ages of a coral reef from Leizhou Peninsula, South China Sea

Systematic mass spectrometric 230Th ages are reported for a Porites coral reef terrace from Dengloujiao,Leizhou Peninsula, South China Sea. Seven episodes of coral growth were recognized in this terrace: 7125±96, 6764±29,5826±37, 5006±54, 2543±24, 1915±15, and 1513±22 calendar years before present (cal. aBP). 50% of the coral age population fall between 7200 and 6600 cal. aBP, marking post-glacial stabdization of global sea level. Considering the facts that ( i ) Dengloujiao reef fiat was measured at 1.6-2.5m above modern tidal datum plane; (ii) modern Porites corals in the South China Sea are living at least ～1 m below the modern tidal datum plane; (iii) the top 20-30 cm of the reef was eroded; and (iv) crustal subsidence in the region since mid-Holocene was negligible, we conclude that the above age groups record at least two major periods (7200-5000 and 2500-1500 cal. aBP) of high sea-level at least 2.9-3.8 m above the present-day level.