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首页> 外文期刊>Palaeogeography, Palaeoclimatology, Palaeoecology: An International Journal for the Geo-Sciences >Magnetostratigraphy of the Miocene Chiang Muan Formation, northern Thailand: Implication for revised chronology of the earliest Miocene hominoid in Southeast Asia
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Magnetostratigraphy of the Miocene Chiang Muan Formation, northern Thailand: Implication for revised chronology of the earliest Miocene hominoid in Southeast Asia

机译：泰国北部中新世清安组的地磁地层学：对东南亚最早的中新世类人石的修订年代学的意义

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A paleomagnetic study has been conducted on the Miocene Chiang Muan Formation in northern Thailand, in order to provide a chronology for the earliest large-bodied Miocene hominoid in Southeast Asia. The Chiang Muan Formation is mainly composed of clay, silt and sand beds, indicating lacustrine and fluvial environments. Paleomagnetic samples were collected from 124 horizons along an approximately 150 m thick section from the Chiang Muan Formation at the opencast Chiang Muan Mine. Rock magnetic experiments and stepwise thermal demagnetizations revealed that the main carrier of the magnetization of the sediments is magnetite and the samples have stable magnetization. Exceptionally, stable magnetization is also carried by hematite, which is represented by red colored sediments. Characteristic remanent magnetization (ChRM) directions, calculated by the principal component analysis, revealed normal or reversed polarities of magnetization, which allow the application of the reversal test of McFadden and McElhinny [McFadden, P.L., McElhinny, M.W., 1990. Classification of the reverse test in paleomagnetism. Geophys. Int. 103, 725-729]. The mean paleomagnetic directions of the normal and reversed polarities passed the reversal test with a classification C, indicating that the Chiang Muan Formation preserved the primary magnetization. in total, five normal and four-reversed polarity zones are recognized from the studied section. Based on paleontological age constraints, this magnetostratigraphic column of the Chiang Muan Formation correlates best with Chron C5AAn-C5n of the geomagnetic polarity time scale (GPTS) from the geological time scale (GTS2004) developed by Gradstein et al. [Gradstein, F., Ogg, J., Smith, A. (Eds.) 2004. A Geological Time Scale 2004. Cambridge Univ. Press, Cambridge, UK, p. 589]. This correlation revealed that sedimentation of the Chiang Muan Formation began approximately at 13 Ma and continued until 9.8 Ma with a mean sedimentation rate of approximately 4.2 cm/ky. The age of the earliest Southeast Asian hominoid is between 12.4 and 13.0 Ma. (c) 2006 Elsevier B.V. All rights reserved.
机译：为了对东南亚最早的大型中新世类人化合物提供年代学，已经对泰国北部的中新世清Chiang组进行了古磁研究。清M组主要由粘土，粉砂和沙层组成，表明湖相和河流环境。在露天的Chiang Muan矿区，从Chiang Muan组约150 m厚的断层中，从124个层位采集古磁样品。岩石磁实验和逐步热退磁表明，沉积物磁化的主要载体是磁铁矿，样品具有稳定的磁化强度。例外地，赤铁矿还具有稳定的磁化强度，赤铁矿以红色沉积物为代表。通过主成分分析计算出的特征性剩余磁化（ChRM）方向显示了正常的或相反的磁化极性，这使得可以应用McFadden和McElhinny的逆转测试[McFadden，PL，McElhinny，MW，1990。在古磁性测试中。地理学。诠释103，725-729]。正极性和反极性的平均古磁方向通过了分类为C的反向测试，表明Chiang Muan组保留了一次磁化强度。总共，从研究的部分中识别出五个正常极性区域和四个相反极性区域。根据古生物学年龄的限制，从Gradstein等人开发的地质时标（GTS2004）来看，Chiang Muan组的地磁地层柱与地磁极性时标（GPTS）的C5AAn-C5n年代最相关。 [Gradstein，F.，Ogg，J.，Smith，A。（编辑）2004。AgeologicalTime Scale2004。剑桥大学。出版社，英国剑桥，p。 589]。这种相关性表明，Chiang Muan组的沉积开始于大约13 Ma，一直持续到9.8 Ma，平均沉积速率约为4.2 cm / ky。最早的东南亚类人猿的年龄在12.4至13.0 Ma之间。 （c）2006 Elsevier B.V.保留所有权利。

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