Essalhi,M., Sizaret,S., Barbanson,L., Chen,Y., Lagroix,F., Demory,F., Nieto,J.M., Saez（aの頭に´）,R. and Capitan（後のaの頭に´）,A（頭に´）.(2011): A case study of the internal structures of gossans and weathering processes in the Iberian Pyrite Belt using magnetic fabrics and paleomagnetic dating. Miner. Deposita, 46, 981-999.

『磁性構造と古磁気年代決定を用いたイベリア黄鉄鉱ベルトにおけるゴッサン（焼け）の内部構造と風化過程の事例研究』

『Abstract
　In the Rio Tinto district of the Iberian Pyrite Belt of South Spain, the weathering of massive sulfide bodies from iron caps, i.e., true gossans and their subsequent alteration and re-sedimentation has resulted in iron terraces, i.e., displaced gossans. To study the structure and evolution of both types of gossans, magnetic investigations have been carried out with two foci: (1) the characterisation and spatial distribution of magnetic fabrics in different mineralised settings, including massive sulfides, gossans, and terraces, and (2) paleomagnetic dating. Hematite has been identified as the susceptibility carrier in all sites and magnetic fabric investigation of four gossans reveals a vertical variation from top to bottom, with: (1) a horizontal foliation refered to as “mature” fabric in the uppermost part of the primary gossans, (2) highly inclined or vertical foliation interpreted as “immature” fabric between the uppermost and lowermost parts, and (3) a vertical foliation interpreted to be inherited from Hercynian deformation in the lowermost part of the profiles. In terraces, a horizontal foliation dominates and is interpreted to be a “sedimentary” fabric. Rock magnetic studies of gossan samples have identified goethite as the magnetic remanence carrier for the low-temperature component, showing either a single direction close to the present Earth field (PEF) direction or random directions. Maghemite, hematite, and occasionally magnetite are the remanence carriers for the stable high-temperature component that is characterized by non PEF directions with both normal and reversed magnetic polarities. No reliable conclusion can be yet be drawn on the timing of terrace magnetization due to the small number of samples. In gossans, the polarity is reversed in the upper part and normal in the lower part. This vertical distribution with a negative reversal test suggests remanence formation during two distinct periods. Remanence in the upper parts of the gossans is older than in the lower parts, indicating that the alteration proceeded from top to bottom of the profiles. In the upper part, the older age and the horizontal “mature” fabric is interpreted to be a high maturation stage of massive sulfides' alteration. In the lower part, the age is younger and the inherited “immature” vertical Hercynian fabric indicates a weak maturation stage. These two distinct periods may reflect changes of paleoclimate, erosion, and/or tectonic motion.

Keywords: AMS; Iberian Pyrite Belt; Gossans; Massive sulfides; Terraces; Magnetic fabric; Paleomagnetic dating』

Introduction
Geological setting of the Iberian Pyrite Belt
　Massive sulfide metallogeny in the IPB
　The gossans in the IPB
Methods and results
　Sampling
　Mineralogy of the gossan and massive sulfide
　Magnetic fabrics study (AMS)
　　Anisotropy of magnetic susceptibility
　　Magnetic susceptibility carrier
　　Magnetic fabrics
　　Paleomagnetic study
Discussion
　Magnetic fabrics in gossan from top to bottom
　Age of the massive sulfides oxidation and chemical remanent magnetization acquisition
　Two-stage alteration of the massive sulfides
　Gossan formation
Conclusions
Acknowledgments
References

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