Laschamp地磁场漂移事件发生的确切年代(~42 ka BP)已通过相对独立的同位素定年手段确定,并被证实具有全球性特征。但这一事件在我国马兰黄土地层中的记录存在着明显的空间差异。本文初步对比了最近发表的黄土高原洛川剖面^(10)Be记录的...Laschamp地磁场漂移事件发生的确切年代(~42 ka BP)已通过相对独立的同位素定年手段确定,并被证实具有全球性特征。但这一事件在我国马兰黄土地层中的记录存在着明显的空间差异。本文初步对比了最近发表的黄土高原洛川剖面^(10)Be记录的Laschamp漂移信息和前人根据该剖面古地磁参数异常结合Heinrich冷事件所确定的Laschamp记录层位结果,进一步证实了这一地磁漂移事件在马兰黄土地层中记录的真实性.同时初步对比也显示根据旧Be产率异常增高对应的磁场强度低值确定的Lashcamp层位偏上,而古地磁异常确定的Laschamp层位相对偏下约76 cm。排除因采样剖面分辨率不同的可能影响,两种手段记录同一地磁漂移事件的显著层位差异具有指示意义,可能为未来研究黄土-古土壤序列沉积剩磁获得过程提供新的途径。展开更多
The Mauna Loa volcano of the Big Island of Hawaii offers the “ad-hoc” lava flows that have recorded the geomagnetic short-term behavior (i.e. excursions) at two key localities such as the younger Kahuku volcanic ser...The Mauna Loa volcano of the Big Island of Hawaii offers the “ad-hoc” lava flows that have recorded the geomagnetic short-term behavior (i.e. excursions) at two key localities such as the younger Kahuku volcanic series (ca. ~41 ka) where 29 flows are exposed for detailed paleomagnetic sampling making up 102 meters of section where the uppermost flow sampled lies directly under the Pahala ash. The second sampling site is the Ninole volcanic series where 25 flows spanning 56 meters of section were also sampled from the northeast and southwest sides of the Kilohana Ridge. The most recent age estimate indicates that the Kahuku flows can correlate well with the transitional/excursional directional results obtained from both volcanic and deep-sea sediments of the global record of the Laschamp (ca. ~41 ka calendar years B.P) excursion and the Ninole flows which are associated to the also global Pringle Fall excursion (ca. 211 ± 13 ka) recorded at the type section.展开更多
The first-order chronological framework of the long-term Chinese loess/paleosol sequences was based mainly on magnetostratigraphy.However,there remain arguments on the lock-in ages of the major geomagnetic reversals.T...The first-order chronological framework of the long-term Chinese loess/paleosol sequences was based mainly on magnetostratigraphy.However,there remain arguments on the lock-in ages of the major geomagnetic reversals.This study systematically compared the stratigraphic locations of the Laschamp excursion and Henrich events(H4 at~39 ka and H5 at~48 ka)recorded by the Luochuan loess profile in the central Chinese Loess Plateau.Results show that the Lascchamp excursion is bracketed well by these two cold events,and the corresponding estimated age is between about 41.7-43.7 ka,which is close to the widely accepted age of~40-41 ka for the excursion.Therefore,our new results do not suggest apparent lock-in effects in the last glacial Malan loess.展开更多
文摘Laschamp地磁场漂移事件发生的确切年代(~42 ka BP)已通过相对独立的同位素定年手段确定,并被证实具有全球性特征。但这一事件在我国马兰黄土地层中的记录存在着明显的空间差异。本文初步对比了最近发表的黄土高原洛川剖面^(10)Be记录的Laschamp漂移信息和前人根据该剖面古地磁参数异常结合Heinrich冷事件所确定的Laschamp记录层位结果,进一步证实了这一地磁漂移事件在马兰黄土地层中记录的真实性.同时初步对比也显示根据旧Be产率异常增高对应的磁场强度低值确定的Lashcamp层位偏上,而古地磁异常确定的Laschamp层位相对偏下约76 cm。排除因采样剖面分辨率不同的可能影响,两种手段记录同一地磁漂移事件的显著层位差异具有指示意义,可能为未来研究黄土-古土壤序列沉积剩磁获得过程提供新的途径。
文摘The Mauna Loa volcano of the Big Island of Hawaii offers the “ad-hoc” lava flows that have recorded the geomagnetic short-term behavior (i.e. excursions) at two key localities such as the younger Kahuku volcanic series (ca. ~41 ka) where 29 flows are exposed for detailed paleomagnetic sampling making up 102 meters of section where the uppermost flow sampled lies directly under the Pahala ash. The second sampling site is the Ninole volcanic series where 25 flows spanning 56 meters of section were also sampled from the northeast and southwest sides of the Kilohana Ridge. The most recent age estimate indicates that the Kahuku flows can correlate well with the transitional/excursional directional results obtained from both volcanic and deep-sea sediments of the global record of the Laschamp (ca. ~41 ka calendar years B.P) excursion and the Ninole flows which are associated to the also global Pringle Fall excursion (ca. 211 ± 13 ka) recorded at the type section.
基金supported by NSFC(Grant No.40221402)and CAS(Grant No.KZCX-3-SW-150).
文摘The first-order chronological framework of the long-term Chinese loess/paleosol sequences was based mainly on magnetostratigraphy.However,there remain arguments on the lock-in ages of the major geomagnetic reversals.This study systematically compared the stratigraphic locations of the Laschamp excursion and Henrich events(H4 at~39 ka and H5 at~48 ka)recorded by the Luochuan loess profile in the central Chinese Loess Plateau.Results show that the Lascchamp excursion is bracketed well by these two cold events,and the corresponding estimated age is between about 41.7-43.7 ka,which is close to the widely accepted age of~40-41 ka for the excursion.Therefore,our new results do not suggest apparent lock-in effects in the last glacial Malan loess.
