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The basal lithology of the overlying
lower Cenomanian Fish Scales Formation is a
regionally extensive bioclastic conglomerate
interpreted as either a wave-winnowed lag
formed during a relative sea-level fall and
subsequent rise, or a current-winnowed lag in
deeper water. Deep-water bottom currents
possibly were generated by mixing of the cool,
low-salinity Boreal waters with warm, normal-salinity
waters of Tethyan affinity as the
Mowry Sea opened to the south forming the
Western Interior Seaway (WIS). Organic matter
is dominantly Type II, comprising a large
component of marine algal material. The overlying
barren, well-laminated sediments that
comprise the bulk of the Fish Scales Formation
were deposited under a stratified water
column with anoxic bottom-waters and are
characterized as a condensed section.
The middle to upper Cenomanian Belle
Fourche Formation conformably overlies the
Fish Scales Formation. A regional sea-level
drop occurred during Belle Fourche time as
indicated by the progradation of Dunvegan
deltaic sediments in northwestern Alberta.
Widespread dysoxic conditions persisted
throughout the middle to late Cenomanian in
this region as shown by the limited agglutinated
foraminiferal assemblage and sparse
bioturbation. Increased detrital input is evident
as an increase in silt content relative to the
Fish Scales Formation and a re-introduction of
significant amounts of Type III organic matter.
The occurrence of numerous bioclastic conglomerates
throughout the upper portion of the
Belle Fourche Formation is possibly the result
of relative sea-level drops affecting areas of
different water depth with variable erosional
intensity.
Maximum transgression in latest Cenomanian
to early Turonian time brought fully marine
conditions and planktic Tethyan fauna
into the Canadian portion of the WIS. This
time period is represented by the Second
White Specks Formation. Productivity in the
upper water column was high and anoxic bottom
waters preserved abundant Type II organic
matter.
Lateral facies variations and a diachronous
introduction of Tethyan foraminifera and
coccoliths to various parts of the basin indicate
pathways of oceanic circulation. The influence
of major Cordilleran detrital sources
limited pelagic faunal development in the west.
A significant unconformity in central Saskatchewan
indicates local basin floor doming
and subsequent erosion in late Turonian to
Santonian time.
2008010055
巴 黎 盆 地 早 白 垩 世 铁 质 鲕 粒 : 土 壤 起 源 对 海
洋 起 源 及 它 们 的 古 气 候 意 义 = Early Cretaceous
iron ooids in the Paris Basin: pedogenic
versus marine origin and their palaeoclimatic
significance. ( 英 文 ). Taylor K G. Cretaceous
Research, 1996, 17(1): 109-118
Oolitic ironstones occur within the subsurface
Lower Cretaceous sediments of the Pays
de l’Ourcq region of the Paris Basin. Goethite
ooids in these ironstones are of three types.
Type 1 ooids are characterized by welldeveloped
concentric lamination and the absence
of a clear nucleus. Type 2 ooids are
characterized by thin, concentrically laminated
cortices and nuclei of iron oxide or quartz
grains. These nuclei show structures (iron oxide
veining in quartz grains, iron oxide platelets)
similar to that formed within lateritic
soils. Type 3 ooids are small, generally lack
concentric lamination and commonly contain
‘desiccation ’ features. The goethite in the
ironstones has negligible Al-substitution, indicative
of formation in the marine environment.
It is proposed that the ooids formed
through accretion on the sea-floor, or just below
the sediment surface. However, the nuclei
of type 2 ooids, and many of the detrital grains
within the ironstones, were derived from lateritic
soils upon nearby massifs. Therefore,
evidence is present within the ironstones for a
warm, sub-tropical climate during the Early
Cretaceous, although the process of oolitic
ironstone formation was most likely controlled
by marine sedimentary processes rather than
climate.
2008010056
贵 州 中 寒 武 世 凯 里 生 物 群 中 纳 罗 虫 ( 节 肢 动
物 门 ) 的 埋 葬 学 = Taphonomy of Naraoiids
(Arthropoda) from the Middle Cambrian Kaili
Biota, Guizhou Province, South China. ( 英 文 ).
Lin J P. Palaios, 2006, 21(1): 15–25 Naraoiids
in the Kaili biota (Taijiangian Stage,
Wulingian Series, lower Middle Cambrian)
are preserved in a variety of taphonomic states.
Decomposition, entombment, and fossil
diagenesis of Kaili naraoiid specimens (n = 69)
are described. The decay rates of appendages,
internal organs, and dorsal sclerites are different,
and should be treated as separate taphonomic
elements. A classification scheme
to delineate the preservational states is proposed
here to distinguish carcasses from molts
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