The Canning Basin of northwestern Australia is a key area tot understanding global changes at the
"Kellwasser Events" and the Frasnian-Famennian boundary.  Frasnian stromatoporoid-coral-cyanobacterial
reef platforms stretched out tot enormous distances along the palaeoshelf but in the early Famennian they
were completely replaced by cyanobacterial reef platforms.  An iridium anomaly in the sequence was
formerly believed to be at or close to the boundary and was interpreted as possible evidence for an asteroid
impact.  Recent field work and detailed biostratigraphy in the area east and southeast of Fitzroy Crossing
has given dating relevant to the tirning and extent of sea level changes, hypoxic incursions and reef
backstepping.  Goniatites and conodonts provide correlations with the international biostratigraphy.

   In the Horse Spring area the stage boundary falls within the Virgin Hills Formation which normally has
a rich pelagic goniatite, nautiloid and conodont fauna.  In the latest Frasnian (Zone 13 of Klapper 1989;
regional Sphaeromanticoceras lindneri Zone) large allochthonous reef blocks moved downslope into the
open marine basin.  A diverse gastropod fauna is associated with the last atrypid brachiopods.  The faunal
record at the immediate boundary is obscured by dolomitisation but manticoceratid goniatites range into
this level.  There is no evidence for the organic-rich dark Kellwasser limestone facies.

   In the McWhae Ridge area two Frasnian goniatite horizons with Beloceras, trilobites and the giant
Manticoceras guppyi and Sphaeromanticoceras lindneri transgress over the reef slope.  Stromatolitic
cyanobacterial beds mark condensations.  Again there is no trace of the oxygen-depleted Kellwasser facies.
However, as at Horse Spring, manticoceratids persisted into dolomitic marker beds that have no other
preserved macrofauna.  The iridium anomaly associated with Frutexites postdates the Frasnian-Famennian
boundary and was formed by cyanobacterial concentration.