Odale articles Callander

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IMPACT CRATER EXPLORATIONS

by: Charles O'Dale

CALLANDER STRUCTURE

The red dot indicates the position of the Joko River spring structure, illustrated here in close proximity to the Brent meteorite crater (highlighted by the circle) in this Landsat image.
The Joko River spring is a 0.2 km diameter structure. (courtesy Google)
  • Age Ma: <..a
  • Diameter: 0.2 km
  • Location: N 46° 33’ 15" W 79° 17’ 13"
aseveral km of Cretaceous sediments fills the cavity .
(Sawatzky, 1977)
(Sawatzky, 1977)
Area Geologic Description: T h e Callander C o m p l e x occupies m u c h of Callander Bay, an almost circular depression about 2.25 miles i n d i a m e t e r at t h e eastern e n d o f L a k e N i p i s s i n g . Most of the c o m p l e x is covered b y water, and its precise extent is u n k n o w n , b u t f r o m geophysical and other data (see section o n " N i o b i u m and U r a n i u m , C a l l a n d e r C o m p l e x " ) and the a v a i l a b l e exposures, all but the southern and e x t r e m e western parts of the bay are p r o b a b l y u n d e r l a i n by t h e c o m p l e x , as s h o w n i n F i g u r e 7. Q u a r t z f e n i t e and aegirine-potassic feldspar f e n i t e u n d e r l i e most of D a r l i n g and M c P h e r s o n Islands i n the western p a r t of the bay ( F i g u r e 7 ) , and the eastern outer p a r t of the c o m p l e x consists of a f e n i t i c zone as m u c h as Vj mile w i d e , w h i c h is well exposed i n road cuts along H i g h w a y 11 and i n Callander. G r a n i t i c and m o n z o n i t ic rocks a l o n g the southern shore of the bay b e t w e e n W a s i Falls a n d S m i t h Island are not f e n i t i z e d except w i t h i n a f e w inches of several l a m p r o p h y r e dikes present along the shore. Shattered, s l i g h t l y f e n i t i z e d g r a n i t o i d rocks, at the outer edge of the eastern f e n i t i c zone, grade i n w a r d towards t h e c e n t r a l p a r t of t h e c o m p l e x t h r o u g h q u a r t z f e n i te t o aegirine-potassic feldspar f e n i t e , w h i c h is i n t r u d e d by n e p h e l i n e syenite along the eastern edge of the bay. E x p l o r a t i o n w o r k (see section on " N i o b i u m and U r a n i u m, C a l l a n d e r C o m p l e x " ) shows t h a t t h e n e p h e l i n e syenite extends b e n e a t h the bay for over Yz m i l e west of the dock at Callander. A n a r r o w n e p h e l i n e syenite cone sheet, r a n g i ng i n w i d t h f r o m 1 foot to 10 feet, i n t r u d e s f e n i t e at t h e l o o k o u t o n H i g h w a y 11 ( F i g u re 7 ) , and a second m o r e extensive n e p h e l i n e syenite cone sheet, u p to 2 0 feet w i d e , i n trudes fenites south and east o f the lookout. A f e w n e p h e l i n e syenite boulders f o u n d in a small area of no o u t c r o p o n the eastern side of H i g h w a y 1 1 , about 2 miles south of t h e southeastern m a r g i n of the c o m p l e x (see M a p 2 2 1 6 , back p o c k e t ) , could m a r k a t h i r d cone sheet off t h e southeastern f l a n k of t h e complex.T h e fenites c o n t a i n numerous carbonate veins a n d are l o c a l l y intensely brecciated and h e m a t i t i z e d , especially near small carbonatite intrusions present i n a f e w places on D a r l i n g and M c P h e r s o n Islands and i n the i n n e r p a r t of the eastern f e n i t i c zone. T he carbonatites are s i m i l a r i n m i n e r a l o g y to those o n Calder I s l a n d i n t h e M a n i t o u Islands C o m p l e x , but p y r o c h l o r e is r e l a t i v e l y rare. Syenitic dikes c o n t a i n i n g altered nepheline are locally present i n aegirine-potassic feldspar f e n i t e. N e p h e l i n e syenite, i n b o t h t h e cone sheets a n d a l o n g t h e eastern shore of t h e bay, is massive and m e d i u m to coarse g r a i n e d and ranges i n c o m p o s i t i o n f r o m foyaite to p u l a s k i t e . Foyaite predominates and consists of about 30 to 4 0 percent euhedral to subhedral n e p h e l i n e i n part p o i k i l i t i c a l l y i n t e r g r o w n w i t h p e r t h i t i c potassic feldspar, f o r m i n g 3 0 t o 4 5 percent of t h e r o c k ; other m i n e r a l s are 10 t o 25 percent a e g i r i n e - a u g i te a n d accessory b i o t i t e , sphene, a p a t i t e , z i r c o n , i r o n - t i t a n i um o x i d e minerals, and m i n or p y r i t e . Pyroxene is p a r t l y altered t o carbonate and fine-grained chloritic m a t e r i a l , and n e p h e l i n e is p a r t l y a l t e r e d to a fine-grained aggregate of zeolites and w h i t e mica w i th finely dispersed h e m a t i t e . P u l a s k i t e is s i m i l a r i n appearance to f o y a i t e b u t is r i c h e r in p e r t h i t i c potassic feldspar and contains less n e p h e l i n e and a e g i r i n e - a u g i t e . I n a few outcrops o n B u r f o r d P o i n t a n d locally i n t h e cone sheets, v e i n l e t s of sodalite cut across t h e n e p h e l i n e syenite. D r i l l cores show that n e p h e l i n e syenite u n d e r l y i n g the bay is intensely h e m a t i t i z e d and carbonatized w i t h u p to 10 percent disseminated p y r i t e and traces of f l u o r i t e ; l a m p r o p h y r e dikes and mafic dikelets r i c h i n altered pyroxene are abundant. These features suggest that c a r b o n a t e - r i c h rocks and possibly alkalic mafic rocks a r e present i n t h e c e n t r a l p a r t o f t h e complex. L a m p r o p h y r e , a n d basaltic a n d p h o n o l i t i c dikes cut across a l l t h e rocks o f the f e n i t ic zone, and these dikes are i n t u r n cut by late calcite and b a r i t e veins, especially i n road cuts a l o n g H i g h w a y 11 south of the lookout. Some of the late calcite veins contain microscopic q u a r t z lenses and the b a r i t e veins c o n t a i n disseminated crystals of specular h e m a t i t e . (Lumbers 1971)
Odale Dumas electric log.jpg
Odale Dumas seismic-.jpg
Odale Dumas Sawatzky1.jpg



References

Geological Report 94 Geology of the North Bay Area Districts of Nipissing and Parry Sound S. B. LUMBERS 1971


Northern Ontario Engineering Geology Terrain Study 101 NORTH BAY AREA (NTS31L/SW) Districts of Nipissing and Parry Sound by John F. Gartner 1

H. B. Sawatzky, Buried impact craters in the Williston Basin and adjacent area, Impact and explosion cratering - Lunar and Planetary Institute 1977


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