The Mia Le formation bearing the Eurjspiri- :er tonkinensis fauna was first described bv the french geologist J.Deprat 1915 as the Mia Le series in Đong Van-Song Nho Q ue section, Hagi
Trang 1IS INTERNATIONAL UNION OF
GEOLOGICAL SCIENCES COMMISSION ON STRATIGRAPHY
SUBCOMMiSSION ON DEVONIAN STRATIGRAPHY
Trang 2Subcominission on Devonian Stratigraphy — Newsletter No n (D ecem ber 1994)
New, Data for Correlation of Early Devonian Bearing the Euryspirifer
tonkinensis fauna in Vietnam and South China
T o n g - D z u y T h a n h & T a H o a P h u o n g
Lower Devonian deposits are wide
spread in North Vietnam and South
China and thanks to the similar faunal
assemblages each psử of formationsTn
both areas is easilv correlated as fol
lows:
Sika Formation of North Vietnam
correlates with Lianhuashan Formation
in South China
Bac Bun Formation = Nagaoling For
mation
Mia Le formation = Yukiang Forma
tion
New data on the Eunsvirư er ionkin-
ensis assemblage characteristic for Mia
Le formation in Vietnam and Its equiv
alent in South China (Yukiang forma
tion) are provided in this comment The
Mia Le formation bearing the Eurjspiri-
:er tonkinensis fauna was first described
bv the french geologist J.Deprat (1915)
as the Mia Le series in Đong Van-Song
Nho Q ue section, Hagiang Province,
northernmost Bac Bo, near the Vietnam-
ese-Chinese frontier, and has been re
vised bv Tong Dzuv Thanh et al.(1988)
The latter author dated this formation
as Pragian in age, while its eauivalent
in south china bearing the similar Eu-
rjsvtrifer ionkincr.sis assemblage is dat
ed as Emsian (Zho g keng, wu vi, vin
baoan et al.1992) (Zhong keng, wuyi, yinbaoanetall.1992) In the Dong Van- Song No Due section marls, shaies and limestone lens of the Mia Le formation lie conformably on the Bac Bun Forma
tion bearing the Howittia xoangi (=ori-
entospirifer xvangi in China) assemblage.
The rocks of Mia Le formation con
tain abundant associations of benthic
faunas in particular corais: Fsvosites
goldfussi, F.saurini, Fstynacus, Emmon- sia yenLicensis,E.iniricatus, Squamsofa- vosiies ccchicus, Sqf.abiauessvinus, Echy- rovora gnndiporcsa, Rcemeripor: bohzrtnc-
us, Hslioiites praepcrosus, Cslceciz ssndali-
na Hzdrcphyium? Srancai, Trypiasma sp., Pseudomicroplasma sp., aillingszstrea sp
and others Bracniopods: Eurvspirifer
tonkinensis, Indospirifer kwangsiensis, Giypicspirifcr chui, Stropheodor.x pattei, Megastrophia aff concava, Dicoelostrcvhia annamiiica, Parachor.etes zeili, Howeilella
sp, Megastrophia oricntûiis, Cymostrcphia sp., Thiemella (?) communis and others
B iv a lv es: M ytilarca (P lecicm vtiiu s)
oviform is.Pteria (corneiites) dochotoma, Pterinea (tolmaia) linealacrezta, Fcsidonia
sp Triiobites: Proetus indosiner.sis, Prae- decheneila sp.
Conformably on the Mia Le forma
tion are beds of black grey, fine-grained lim estone with marl, peiitomoxphic
limestone and coaly shale interbeds In addition.some black, thin (2-8 cm), very hard siliceous interbeds are observed in the sequence In these beds an abun dant tentaculites association has just been collected and indentified,from the bottom upwards the following species
have been identified: Nowakia acuaria,
N z lic h o v rsis, N.mana, N.praecursor,
N ex gr.tu rran dei and ch itin ozoan s Bursachitina riclcmer.sis (paris et al 1993)
At the same level Pham kim ngan 1981
has discovered conoaonts Polvgnatkus
perbonus, Spathognsrhodus steinhornertsis,
S optimus, Hindeoddla denckmanni, Tri- chonoddla symciricz From the upper
layers of these beds some conodonts have just been identified by Ta Hoa
Phuong :3eloaeUa devonica, Panderodus
unLjstatatus , Pandorinellina sp, Polyg nathus linguifomus linguijomris.
CONCLUSION' The above-mentioned data provide
a convincing basic far identifying the
Mia Le formation bearing the Euryspiri-
fer tonkinensis fauna in the Dong Van -
Song No Due secr.or in particular, and
in North Vietnam :n common as Pragi-
an in age Its equivalent (Yukiang For mation) in South China bearing the sim
ilar Eurysvirifer :onhncr.sis inur.a may
be of the same age
Integrated study of conodont biostratigraphy and physical stratigraphy of the
Beaverhill Lake Group (Late Givetian to Early Frasnian), Western Canada
T o m U y e n o a n d J a c k W e n d t e ( G e o l o g i c a l S u r v e y o f C a n a d a , C a l g a r y , A l b e r t a )
The authors are conducting an in
tegrated study of conodont biostratig
raphy and physical stratigraphy of the
Beaverhill Lake Group (BhLGr) (210 m
thick; late Givetian to early Frasnian)
across the Western Canada Sedimenta
ry Basin of Alberta We recognize ma
jor depositionai successions from the
study of cores and they are correlated
across the basin using wireline logs
Cores are extensively sampled in each
of the m ajor depositionai successions
The BhL Gr extends from the Watt
M ountain Formation (Fm) of the Elk
Point Gr to the platformal carbonates
of the Cooking Lake Fm or the deeper- water basinal equivalents, the Duver- nay Fm, both of the Woodbend Gr The underlying Watt Mountain Fm includes carbonates, evaporites and terrigenous sediments deposited on a coastal plain
or in a very shallow sea The BhL Gr is divided into nine major depositionai cycles, and the shifts of facies in these depositionai cycles define two major transgressive-regressive (T-R) succes
sions The lower major T-R cycle ex
tends from the top of the Watt Moun
tain Fm to the the top of Cycle D, a po
-69-sition equivalent to about the middle
of the Moberlv Member (Mbr) of the Waterways Fm (of the old stratigraph-
ic terminology; see Uyeno, 1974) This cycle includes conodont zones ranging from w ithin the subterminus Fauna (approximately Upper disparilis Sub zone; see Klapper, in Witzke et ai„ 1985; Klapper and Johnson in Johnson, 1990)
to the lower part of Klapper's (1989) Zone MN3 The upper major T-R cycle extends from the top of Cycle D to the base of the Woodbend Gr and corre sponds to the upper naif of the Mober
lv Mbr and '.he Mildred M br of the