02439nas a2200217   4500000000100000008004100001100001700042700002000059700001700079700002500096700002100121700001900142700001900161700002300180700001700203245009600220856006700316300002200383490000700405520180900412       2013                            d1 aDavid Hodell1 aSimon Crowhurst1 aLuke Skinner1 aPolychronis Tzedakis1 aVasiliki Margari1 aJames Channell1 aGeorge Kamenov1 aSuzanne Maclachlan1 aGuy Rothwell00aResponse of Iberian Margin sediments to orbital and suborbital forcing over the past 420 ka  uhttp://onlinelibrary.wiley.com/doi/10.1002/palo.20017/abstract  a185\textendash1990 v283 a<p>Here we report 420 kyr long records of sediment geochemical and color variations from the southwestern Iberian Margin. We synchronized the Iberian Margin sediment record to Antarctic ice cores and speleothem records on millennial time scales and investigated the phase responses relative to orbital forcing of multiple proxy records available from these cores. Iberian Margin sediments contain strong precession power. Sediment \textquotedblleftredness\textquotedblright (a* and 570\textendash560 nm) and the ratio of long-chain alcohols to n-alkanes (C26OH/(C26OH + C29)) are highly coherent and in-phase with precession. Redder layers and more oxidizing conditions (low alcohol ratio) occur near precession minima (summer insolation maxima). We suggest these proxies respond rapidly to low-latitude insolation forcing by wind-driven processes (e.g., dust transport, upwelling, precipitation). Most Iberian Margin sediment parameters lag obliquity maxima by 7\textendash8 ka, indicating a consistent linear response to insolation forcing at obliquity frequencies driven mainly by high-latitude processes. Although the lengths of the time series are short (420 ka) for detecting 100 kyr eccentricity cycles, the phase relationships support those obtained by Shackleton [2000]. Antarctic temperature and the Iberian Margin alcohol ratios (C26OH/(C26OH + C29)) lead eccentricity maxima by 6 kyr, with lower ratios (increased oxygenation) occurring at eccentricity maxima. CO2, CH4, and Iberian SST are nearly in phase with eccentricity, and minimum ice volume (as inferred from Pacific δ18Oseawater) lags eccentricity maxima by 10 kyr. The phase relationships derived in this study continue to support a potential role of the Earth\textquoterights carbon cycle in contributing to the 100 kyr cycle.</p>