Microfloristic assemblages have been recovered from the Hirnantian-aged Hassi el Hadjar (‘Argiles Microconglomratiques’) and M’Kratta formations in borehole Nl-2, northeast Algerian Sahara. These formations are genetically related to glacial sedimentary dynamics, and represent, according to previous analysis, glacial diamictites resulting from the melting of the Saharan ice cap, and post-glacial shelf conditions, respectively. Previous studies have analyzed in detail the microplankton (acritarchs and chitinozoans) content of the Nl-2 section, providing precise biostratigraphic control. This contribution presents for the first time a diverse Hirnantian miospore microflora from Algeria, comprising cryptospores and trilete spores, and compares it with previously reported coeval spore assemblages from worldwide localities at different palaeolatitudes. The palynological microfloristic association is mainly characterized by cryptospores in permanent tetrad and dyad configurations, along with minor occurrences of laevigate monads and rare trilete spores. The present results, in conformity with previous suggestions, show apparent planet-scale homogeneity of the bryophyte-like earliest terrestrial flora during Hirnantian times. The diversity and abundance of early land plants was not affected by the Hirnantian glaciation.
Latest Ordovician (Hirnantian) miospores from NL-2 well, Algeria, North Africa, and their evolutionary significance
SPINA, AMALIA
2015
Abstract
Microfloristic assemblages have been recovered from the Hirnantian-aged Hassi el Hadjar (‘Argiles Microconglomratiques’) and M’Kratta formations in borehole Nl-2, northeast Algerian Sahara. These formations are genetically related to glacial sedimentary dynamics, and represent, according to previous analysis, glacial diamictites resulting from the melting of the Saharan ice cap, and post-glacial shelf conditions, respectively. Previous studies have analyzed in detail the microplankton (acritarchs and chitinozoans) content of the Nl-2 section, providing precise biostratigraphic control. This contribution presents for the first time a diverse Hirnantian miospore microflora from Algeria, comprising cryptospores and trilete spores, and compares it with previously reported coeval spore assemblages from worldwide localities at different palaeolatitudes. The palynological microfloristic association is mainly characterized by cryptospores in permanent tetrad and dyad configurations, along with minor occurrences of laevigate monads and rare trilete spores. The present results, in conformity with previous suggestions, show apparent planet-scale homogeneity of the bryophyte-like earliest terrestrial flora during Hirnantian times. The diversity and abundance of early land plants was not affected by the Hirnantian glaciation.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
