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Coastal sediments from the Algarve: low-latitude climate archive for the Aptian-Albian


Heimhofer, U; Adatte, T; Hochuli, P A; Burla, S; Weissert, H (2008). Coastal sediments from the Algarve: low-latitude climate archive for the Aptian-Albian. International Journal of Earth Sciences, 97(4):785-797.

Abstract

The Late Aptian to Early Albian transition has
previously been identified as a possible example of substantial
climate cooling within the mid-Cretaceous greenhouse
period. To study the response of continental
weathering and terrestrial vegetation to this cooling episode
at low- to mid-latitudes, marine nearshore deposits
from the Algarve Basin (SW Portugal) have been investigated
with a combined approach including palynology,
clay mineralogy and bulk-rock geochemistry. In the Lower
Aptian part of the succession, quartz-rich sandstone facies
is accompanied by high abundances of early diagenetic
kaolinite, which is interpreted to reflect episodes of enhanced
humidity and high meteoric flow-through. In contrast,
the Late Aptian to Early Albian deposits are
characterized by high abundances of detrital clay minerals
(mica and chlorite) indicating the dominance of physical
weathering processes in the source area, most probably
related to low precipitation rates in conjunction with tectonically
enhanced erosion. Palynological data show a
strong dominance of Classopollis pollen associated with
low pteridophyte spore abundances, suggesting warm
semi-arid to arid palaeoenvironments. Changes in sedimentation
patterns from varicoloured lagoonal marls to
thick-bedded shallow-water carbonates are neither expressed
in the spore-pollen assemblages nor in the distributions
of clay minerals which both remain essentially
stable throughout the Late Aptian to Early Albian. These
relatively stable patterns are in contrast with various lines
of evidence, predominantly from high-latitude areas, that
suggest a significant cooling during this time interval. Our
study demonstrates that terrestrial environments of low- to
mid-latitude regions were not significantly affected by the
Late Aptian - Early Albian ‘‘cold snap’’.

Abstract

The Late Aptian to Early Albian transition has
previously been identified as a possible example of substantial
climate cooling within the mid-Cretaceous greenhouse
period. To study the response of continental
weathering and terrestrial vegetation to this cooling episode
at low- to mid-latitudes, marine nearshore deposits
from the Algarve Basin (SW Portugal) have been investigated
with a combined approach including palynology,
clay mineralogy and bulk-rock geochemistry. In the Lower
Aptian part of the succession, quartz-rich sandstone facies
is accompanied by high abundances of early diagenetic
kaolinite, which is interpreted to reflect episodes of enhanced
humidity and high meteoric flow-through. In contrast,
the Late Aptian to Early Albian deposits are
characterized by high abundances of detrital clay minerals
(mica and chlorite) indicating the dominance of physical
weathering processes in the source area, most probably
related to low precipitation rates in conjunction with tectonically
enhanced erosion. Palynological data show a
strong dominance of Classopollis pollen associated with
low pteridophyte spore abundances, suggesting warm
semi-arid to arid palaeoenvironments. Changes in sedimentation
patterns from varicoloured lagoonal marls to
thick-bedded shallow-water carbonates are neither expressed
in the spore-pollen assemblages nor in the distributions
of clay minerals which both remain essentially
stable throughout the Late Aptian to Early Albian. These
relatively stable patterns are in contrast with various lines
of evidence, predominantly from high-latitude areas, that
suggest a significant cooling during this time interval. Our
study demonstrates that terrestrial environments of low- to
mid-latitude regions were not significantly affected by the
Late Aptian - Early Albian ‘‘cold snap’’.

Citations

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:07 Faculty of Science > Paleontological Institute and Museum
Dewey Decimal Classification:560 Fossils & prehistoric life
Uncontrolled Keywords:Early Cretaceous - Algarve Basin - Palaeoclimate - Palynology - Clay mineralogy
Language:English
Date:July 2008
Deposited On:10 Feb 2009 15:24
Last Modified:05 Apr 2016 12:46
Publisher:Springer
ISSN:1437-3254
Publisher DOI:https://doi.org/10.1007/s00531-007-0186-y

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