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2008010050
意 大 利 中 部 Umbria-Marche 盆 地 Selli 层
的 有 机 物 特 征 = Organic matter characterisation
of the Selli Level (Umbria-Marche Basin,
central Italy). ( 英 文 ). Baudin F; Fiet N; Coccioni
R; Galeotti S. Cretaceous Research,
1998, 19(6): 701-714
The Selli Level is a marker-bed in the
Umbria-Marche Apennines that represents the
regional sedimentary expression of the Lower
Aptain Oceanic Anoxic Event 1a. This one to
three-metre-thick interval shows a remarkable
uniformity on a regional scale, with a green to
grey marly lower part overlain by black shales.
Bulk geochemical studies and an examination
of palynofacies were carried out on three sections
in order to characterise the distribution
and nature of the organic matter in the Selli
Level which has been poorly known hitherto.
The organic content is medium (0.5 to 2.9%
TOC) in the basal part and higher (4.5% on
average, and up to 18% TOC) in the black
shales. Pyrolysis and palynological data indicate
that the organic matter is mainly of marine
origin. The geochemical characteristics of
the Selli Level are compared to other, more or
less organic-rich marker-beds in the Cretaceous
succession of the Umbria-Marche Apennines.
2008010051
英 格 兰 东 南 部 下 白 垩 统 Weald Clay 组 植
物 、 昆 虫 及 其 他 有 机 壁 微 体 化 石 的 古 环 境
意 义 = Palaeonenvironmental implications of
plant, insect and other organic-walled microfossils
in the Weald Clay Formation (Lower
Cretaceous) of southeast England. ( 英 文 ).
Batten D J. Cretaceous Research, 1998, 19(3-
4): 279-315
A remarkable variety of plant and other
organic-walled microfossils that are between
0.1 and 5.0 mm in maximum diameter have
been recovered from two Weald Clay sections
in Surrey, southeast England. The associations
of these ‘mesofossils’ with each other, and
with lithofacies, invertebrate macro- and microfossil
occurrences and palynofacies require
further investigation, but among a number of
preliminary conclusions that have been drawn
based on the data accumulated so far are the
following. The amount of particulate organic
matter of mesofossil size in a bed can usually
be estimated from the general aspect of the
lithology, but its composition is much harder
to predict. As for older Wealden (Hastings
Beds) occurrences, deposits in which megaspores
are abundant often contain scattered
small wood and cuticle fragments that are
visible to the naked eye. Those displaying remains
of insects of similar or larger size tend,
not surprisingly, to yield the richest assemblages
of mesofossil-sized fragments of this
group. However, such zooclasts occur more
widely than is apparent from the horizons that
are obviously insect-bearing. This suggests
that, more often than has generally been appreciated,
minute black particles in standard
palynological preparations of nonmarine
sedimentary successions may include arthropod
fragments. The common occurrence of
charred remains ofWeichselia reticulataand
other plants in association with disarticulated
bits of insects may partly reflect both a type of
vegetation that was prone to desiccation and
some of the insects that lived within it, lightning-induced
fire during droughts having been
responsible for their death. A tendency towards
an inverse relationship between this
plant-insect association and large numbers of
megaspores and/or seeds indicates that other
habitats are also represented. Several of the
megaspore genera are probably the products
of aquatic or waterside plants. Delicate leafy
shoots of uncertain affinity occur in several
beds, but the general scarcity of larger pieces
of wood and foliage suggests that the conifers
and other gymnosperms may have been confined
mainly to better drained parts of the
Wealden lowland, and to the higher ground
bordering it. Indicators of fresh to low salinity
water were recovered from more than half of
the samples examined. This is consistent with
the general environment of sediment deposition
inferred from the associated invertebrate
faunas and dinoflagellate cyst assemblages.
2008010052
英 格 兰 南 部 Isle 下 白 垩 统 Wealden 群 介 壳
层 的 古 环 境 分 析 : 一 次 初 步 尝 试 = Palaeoenvironmental
analysis of shell beds in the
Wealden Group (Lower Cretaceous) of the
Isle of Wight, southern England: an initial
account. ( 英 文 ). Radley J D; Barker M J. Cretaceous
Research, 1998, 19(3-4): 489-504
Initial results of a palaeoenvironmental
study of Wealden shell beds on the Isle of
Wight, southern England are presented. Wellpreserved
biofabrics reflect ‘background’ and
‘event’ depositional processes in coastal alluvial
plain and marginal marine lagoonal environments.
‘Event’ deposits are largely attributable
to overbank floods in alluvial facies and
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