One　of　the　five　great　mass　extinctions　of　the　Phanerozoic　is　the　Frasnian-Famennian　(F-F)　mass　extinction,　for　which　the　causes　have　not　yet　been　identified.　In　this　study,　cyclostratigraphic　analysis　of　two　F-F　transition　sections　was　carried　out　in　South　China:　the　Yangdi　section,　a　marine　slope　facies,　and　the　Lali　section,　a　marine　basin　facies.　Paleoclimate　proxy　data　collected　at　high　resolution　along　these　sections　include　magnetic　susceptibility　and　X-ray　fluorescence　geochemistry　(Ca　and　Fe　concentrations).　Time　series　analysis　and　modeling　of　the　proxy　data　reveal　that　frequencies　comparable　to　those　of　the　Earth＇s　long　and　short　orbital　eccentricity,　obliquity,　and　precession　index　characterize　the　two　successions.　Metronomic　405-kyr　long　orbital　eccentricity　cycles　identified　along　the　two　sections　were　used　to　construct　a　floating　astronomical　time　scale　across　the　F-F　transition,　revealing　that　1000　kyr　separates　the　Lower　and　Upper　Kellwasser　horizons　(LKH　and　UKH),　and　similar　to　1600　kyr　separates　the　maximum　values　of　the　LKH　and　UKH　delta　C-13　excursions.　The　estimated　duration　of　the　UKH　is　150　kyr,　during　which　the　first,　second,　and　third　extinctions　of　the　F-F　biotic　crisis　lasted　120　kyr,　20　kyr,　and　10　kyr,　respectively.　Sedimentary　noise　models　of　the　magnetic　susceptibility　and　Ca　concentration　time　series　indicate　that　changes　in　sedimentary　noise　correspond　to　sea　level　variations.　Modeling　suggests　that　the　long　orbital　eccentricity　cycles　controlled　sea　surface　temperatures,　and　that　third-order　eustatic　changes　were　forced　by　the　combined　orbital　eccentricity　and　obliquity　variations.　Finally,　we　propose　an　＂astronomical　climate　change＂　model　as　a　defining　mechanism　of　the　F-F　biotic　crisis.