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We present the results of magnetic fabric analysis obtained on samples of marine clays from sedimentary sequences in Northwestern Greece and Taiwan, in regions which have been submitted to large scale compressional events. The lithology of the sediments is mainly composed of unmetamorphosed marls, siltstones and sandstones. These formations are folded and faulted at different scales. The magnetic fabric is largely sedimentary. However both at single sites (Taiwan) and regionally (Greece) the magnetic lineation is systematically perpendicular to the main compressive stress σ1 inferred from previous fault tectonic analysis. This is an indication that the fabric is also partly of tectonic origin. In Northwestern Greece the orientation of the magnetic susceptibility ellipsoid is constant over distances exceeding 200 km, suggesting that the orientation of the principal compressive strain relative to the trend of the main structures lias been constant since Lower Oligocene.

Four basic magnetic parameters (11:, SIRM, Her, MDFsrRM) and two thermal magnetic analyses were investigated in this study to characterize the magnetic properties of magnetite-, pyrrhotite• and greigite-bearing rocks of the Tsengwen-chi and Erhjen-chi sections. These rocks. have very similar behaviors in the acquisition of isothermal remanent magnetization (IRM) in spite of bearing with different magnetic minerals. Because of the difference in magnetic mineral concentration and grain size, greigite-, pyrrhotite-, and magnetite-bearing rocks have relatively high, intermediate and low parameter values (11:, SIRM, Her, MDF sr RM), respectively. Thermomagnetic analysis in a nitrogen atmosphere has further revealed that each magnetic mineral has its own diagnostic magnetization curves and that greigite could have trans formed to pyrrhotite and magnetite, pyrrhotite to magnetite, and magnetite to hematite. Bulk magnetic susceptibility has also shown remarkable drop in greigite-bearing rocks below 320°C, while there are minor and almost non effective susceptibility changes in pyrrhotite-and magnetite-bearing rocks below 400° C, respectively.

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We studied diatoms in a 55.5-cm-long sediment core from a subalpine lake in northern Taiwan, Tsuifong Lake (TFL), to investigate environmental changes from AD 490 to present. Diatom assemblages of the last century were dominated by acidophilous species, whereas alkaliphilous taxa dominated the record between AD 1480 and 1910. Over the studied time frame, four decadal periods with high precipitation were inferred from evidence of elevated soil input from the watershed, supported by the stable isotope signatures (d 15 N, d 13 C) of organic matter and magnetic susceptibility of the sediments. We compared the inferred changes in pH of TFL to values obtained from three other Taiwanese subalpine lakes. The present study revealed that elevated precipitation was associated with increased solar irradiance over the last five centuries, with a stable dry period between AD 490 and 1450. Acidification of TFL in the last *100 years was a consequence of deforestation and acid rain.