FUZZY C-MEANS CLUSTER-ANALYSIS OF EARLY DIAGENETIC EFFECTS ON NATURAL REMANENT MAGNETIZATION ACQUISITION IN A 1.1 MYR PISTON CORE FROM THE CENTRAL MEDITERRANEAN

被引:53
作者
DEKKERS, MJ [1 ]
LANGEREIS, CG [1 ]
VRIEND, SP [1 ]
VANSANTVOORT, PJM [1 ]
DELANGE, GJ [1 ]
机构
[1] UNIV UTRECHT,INST EARTH SCI,DEPT GEOCHEM,3584 CD UTRECHT,NETHERLANDS
关键词
D O I
10.1016/0031-9201(94)90014-0
中图分类号
P3 [地球物理学]; P59 [地球化学];
学科分类号
0708 ; 070902 ;
摘要
The influence of early diagenesis on the natural remanent magnetisation (NRM) in sediments from the Calabrian ridge (Central Mediterranean) is analysed with the help of fuzzy c-means (FCM) cluster analysis and non-linear mapping (NLM). The sediments are variably coloured: white, beige, purplish, greenish and grey layers occur with occasionally intercalated sapropels. The NRM acquired depends on both depositional conditions and diagenetic processes. To describe these, FCM was performed with chi(in), ARM, CaCO3, Ba, Mn and S as variables. An eight-cluster model was derived with the clusters belonging to two categories: one expressing mainly diagenetic processes, i.e. dissolution and precipitation, and the other expressing mainly depositional conditions. The impact of diagenesis on NRM acquisition is profound and not restricted to the close vicinity of the anoxic sapropelitic layers. As a consequence, the influence of diagenetic processes on the NRM should be thoroughly assessed when selecting samples, e.g. for the determination of the relative palaeointensity of the geomagnetic field. Application of multivariate classification techniques appears to be useful because it links rock magnetic parameters to the geochemical environment. In the present piston core, three short reversed geomagnetic events in the Brunhes chron are preserved and, indeed, occur in clusters expressing no or minor diagenesis. The recording of the Blake event, however, has been prevented by later precipitation of magnetite in the corresponding interval.
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页码:155 / 171
页数:17
相关论文
共 47 条
[41]   A PALEOMAGNETIC AND GEOCHEMICAL RECORD OF THE UPPER COCHITI REVERSAL AND 2 SUBSEQUENT PRECESSIONAL CYCLES FROM SOUTHERN SICILY (ITALY) [J].
VANHOOF, AAM ;
VANOS, BJH ;
RADEMAKERS, JG ;
LANGEREIS, CG ;
DELANGE, GJ .
EARTH AND PLANETARY SCIENCE LETTERS, 1993, 117 (1-2) :235-250
[42]   OCCURRENCE OF THIN, METAL-RICH LAYERS IN DEEP-SEA SEDIMENTS - A GEOCHEMICAL CHARACTERIZATION OF COPPER REMOBILIZATION [J].
VANOS, B ;
VISSER, HJ ;
MIDDELBURG, JJ ;
DELANGE, GJ .
DEEP-SEA RESEARCH PART I-OCEANOGRAPHIC RESEARCH PAPERS, 1993, 40 (09) :1713-1730
[43]   POSSIBLE DIAGENETIC MOBILIZATION OF BARIUM IN SAPROPELIC SEDIMENT FROM THE EASTERN MEDITERRANEAN [J].
VANOS, BJH ;
MIDDELBURG, JJ ;
DELANGE, GJ .
MARINE GEOLOGY, 1991, 100 (1-4) :125-136
[44]  
VANOS BJH, 1994, IN PRESS PALEOCEANOG
[45]  
VANVELZEN AJ, 1993, TERRA NOVA S1, V5, P93
[46]  
VRIEND SP, 1988, APPL GEOCHEM, V3, P213, DOI DOI 10.1016/0883-2927(88)90009-1
[47]   FUZZY SETS [J].
ZADEH, LA .
INFORMATION AND CONTROL, 1965, 8 (03) :338-&