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and in the southern Karoo Basin, carbonate<br />
nodular horizons. A change in colour of the<br />
mudstones from green-grey to red-brown<br />
takes place at the palaeontologically defined<br />
boundary. Variations in the major and trace<br />
element abundance profiles are usually limited<br />
to the carbonate nodular horizons, besides the<br />
overall effects of weathering. Bulk carbon<br />
isotopic studies of the Commando Drift Dam<br />
section revealed a negative δ 13 C bulk excursion<br />
(background values of −15 to −20‰, with<br />
total extent of excursion to −24.9‰) 2 cm<br />
below the palaeontological boundary, followed<br />
by a gradual recovery and then another<br />
decrease in values leading towards the palaeomagnetic<br />
boundary. Above this boundary<br />
recovery to less negative δ 13 C bulk values (ca.<br />
−18‰) occurs. The organic carbon record<br />
from the Commando Drift Dam (southern Karoo<br />
Basin) and Injusiti (eastern Karoo Basin)<br />
oscillates between −26.1 and −28.9‰, which<br />
is comparable to previous studies of different<br />
sections in the southern Karoo Basin. The<br />
magnitude of both the bulk and organic carbon<br />
isotopic variation can be interpreted to indicate<br />
a number of inputs (due to the fluctuating<br />
values) of organic carbon. The carbon isotope<br />
data for carbonates in the Injusiti section are<br />
different from the results on carbonates from<br />
other studies, but more work to expand this<br />
dataset is necessary. The palynological studies<br />
on the Commando Drift Dam section reveal<br />
the presence of a low diversity flora composed<br />
principally of bryophytes, lycophytes, and<br />
gymnosperms. These forms, including several<br />
Late Permian key-species, are traces of the<br />
surviving plants enduring after the major extinction-pulse.<br />
The presence of fungal palynomorphs<br />
and dearth of pollen/spores related<br />
to photosynthetic plants some metres above<br />
the palaeontological P–Tr boundary demonstrate<br />
similarities to the pattern of floral extinction<br />
at the Cretaceous–Palaeogene (K–Pg)<br />
boundary. The timing of vertebrate extinctions<br />
in the Karoo Basin has so far not been determined,<br />
but the 252.5 Ma age for a single zircon<br />
crystal from Commando Drift Dam dated<br />
here gives a maximum constraint on the age of<br />
the event bed, which is in agreement with the<br />
accepted age of the boundary. No evidence for<br />
impact-produced microdeformation features<br />
were found in quartz grains from either the<br />
Wapadsberg or Commando Drift Dam sections.<br />
Also, siderophile element data (including<br />
platinum group element (PGE) concentrations)<br />
do not support the possible presence of<br />
a meteoritic component at the boundary. Thus,<br />
a link between impact and P–Tr extinction is<br />
not indicated by the results of this study.<br />
2008010457<br />
华 南 广 西 来 宾 - 合 山 二 叠 系 生 物 地 层 和 岩 相<br />
= Biostratigraphy and lithofacies of the Permian<br />
System in the Laibin–Heshan area of<br />
Guangxi, South China. ( 英 文 ). Shen<br />
Shuzhong; Wang Yue; Henderson C M; Cao<br />
Changqun; Wang Wei. palaeoworld, 2007,<br />
16(1-3): 120-138<br />
The Laibin–Heshan area is probably a<br />
unique area containing a suitable marine reference<br />
for the entire Permian system. Various<br />
fossils, sedimentary characteristics, lithofacies<br />
and palaeoenvironments including near shore,<br />
distal shelf, slope, and basin are developed.<br />
The Permian system in the Laibin–Heshan<br />
area is composed of the Maping, the Chihsia,<br />
the Maokou, the Heshan/Wuchiaping and the<br />
Talung formations in ascending order. The<br />
Maping Formation is characterized by restricted<br />
shoal or intertidal facies and ranges<br />
from the Late Carboniferous Kasimovian to<br />
Early Permian Artinskian. The Chihsia Formation<br />
(Artinskian–Kungurian) and the Maokou<br />
Formation (Roadian–Capitanian) represent<br />
a slope carbonate environment and a<br />
transgressive interval. By the end of the Guadalupian,<br />
the Permian sea was reduced to the<br />
confines of the Laibin area in South China and<br />
nearshore massive crinoid limestone was deposited,<br />
representing the most continuous marine<br />
deposits across the Guadalupian–<br />
Lopingian boundary. The Lopingian sequence<br />
in the Laibin–Heshan area reflects an independent<br />
transgression–regression system. During<br />
the Wuchiapingian basinal or slope phase,<br />
siliceous siltstone and chert and carbonates<br />
were deposited. During the Changhsingian,<br />
the Laibin–Heshan area subsided rapidly, accumulating<br />
about 600 m of limestone, tuffaceous<br />
sandstone, shale, siltstone before the<br />
basin was drained and terrestrial clastics with<br />
coal-seams developed. The end of the<br />
Changhsingian reflected the initial stage of the<br />
rapid transgression of the Triassic forthcoming<br />
supercycle. Limestone with latest Permian<br />
benthic faunas developed during the last stage<br />
of the Permian, which were immediately replaced<br />
by the nektic ammonoid and bivalvedominated<br />
faunas in the earliest Triassic.<br />
2008010458<br />
意 大 利 南 阿 尔 卑 斯 二 叠 纪 地 层 和 大 地 构 造<br />
评 述 = A stratigraphic and tectonic review of<br />
the Italian Southern Alpine Permian. ( 英 文 ).<br />
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