scholarly journals Stratigraphic Studies of Lower To Middle Jurassic Rocks in the Mt. Waddington and Taseko Lakes map Areas, British Columbia

1991 ◽  
Author(s):  
P J Umhoefer ◽  
H W Tipper
Keyword(s):  
British Columbia ◽  
Middle Jurassic ◽  
Jurassic Rocks

Eocene age for Ag–Pb–Zn–Au vein and replacement deposits of the Kokanee Range, southeastern British Columbia

1992 ◽  
Vol 29 (1) ◽  
pp. 3-14 ◽  
Author(s):  
G. Beaudoin ◽  
J. C. Roddick ◽  
D. F. Sangster
Keyword(s):  
British Columbia ◽  
Middle Jurassic ◽  
Middle Eocene ◽  
Hanging Wall ◽  
Spatial Association ◽  
High Heat ◽  
Time Interval ◽  
Genetic Link ◽  
Metasedimentary Rocks ◽  
Magmatic Event

The Ag–Pb–Zn–Au vein and replacement deposits of the Kokanee Range, southeastern British Columbia, are hosted by the Middle Jurassic Nelson batholith and surrounding Cambrian to Triassic metasedimentary rocks in the hanging wall of the transcrustal Slocan Lake Fault, Field relations indicate that mineralization is younger than the Nelson batholith and a Middle Jurassic foliation in the Ainsworth area but coeval or older than Eocene unroofing of the Valhalla metamorphic core complex in the footwall of the Slocan Lake Fault. Lamprophyre and gabbro dykes are broadly coeval with mineralization and have biotite and hornblende K–Ar ages defining a short-lived Middle Eocene alkaline magmatic event between 52 and 40 Ma. An older, Early Cretaceous alkaline magmatic event (141 – 129 Ma) is possible but incompletely documented.K–Ar and step-heating 40Ar/39Ar analyses on hydrothermal vein and alteration muscovite indicate that hydrothermal fluids were precipitating vein and replacement deposits 58–59 Ma ago. Crosscutting relationships with lamprophyre dykes indicate the Kokanee Range hydrothermal system lasted for more than 15 Ma. Eocene crustal extension resulted in a high heat flow and structures which were probably responsible for hydrothermal fluid movement and flow paths.A 100 Ma time interval is documented between batholith emplacement and spatially associated mineralization, ruling out any genetic link between the two. Similar large age differences between granite intrusion and peripheral mineralization have recently been documented for two world-sea le Ag–Pb–Zn vein districts, which suggest that spatial association between granite and Ag–Pb–Zn mineralization is not sufficient to infer a genetic link.

First post-Triassic temnospondyl amphibians from the Shan-Thai block: intercentra from the Jurassic of peninsular Thailand

1994 ◽  
Vol 131 (6) ◽  
pp. 837-839 ◽  
Author(s):  
Eric Buffetaut ◽  
Lertsin Raksaskulwong ◽  
Varavudh Suteethorn ◽  
Haiyan Tong
Keyword(s):  
Middle Jurassic ◽  
Precise Identification ◽  
Jurassic Rocks ◽  
Northeastern Thailand

AbstractTwo temnospondyl intercentra from non-marine middle Jurassic rocks at Mab Ching, in the southern peninsula of Thailand, are the first remains of post-Triassic labyrinthodont amphibians to be reported from the Shan-Thai block. They closely resemble an intercentrum recently reported from the middle Jurassic of the Khorat Plateau of northeastern Thailand, which is part of the Indochina block. Although the Mab Ching specimens are too fragmentary to warrant a precise identification, they confirm that temnospondyl amphibians were widespread on the various Asian continental blocks in the Jurassic.

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