TY - JOUR

T1 - Halite pseudomorphs in the Crato Formation (Early Cretaceous, Late Aptian-Early Albian), Araripe Basin, northeast Brazil

T2 - further evidence for hypersalinity

AU - Martill, David M.

AU - Loveridge, Robert

AU - Heimhofer, Ulrich

N1 - Funding Information: We thank Drs Paulo Brito, Artur Andrade and André Herzog for their help and encouragement while in Brazil, Mr Geoff Long for his high quality thin section preparation and Mr Roger Pulley and Ms Tai Wilson for logistical support. DMM thanks Professor John Hudson for helpful discussion. We are especially grateful to Sr Betimar Filgueira of DNPM Crato who made available for analysis specimens collected from Sitio Romualdo by Dr P.-Y. Berthou (deceased). Financial support to U.H. from DFG project HE4467/1 is gratefully acknowledged.

PY - 2007/8

Y1 - 2007/8

N2 - Pseudomorphs after hopper-faced halite occur at several horizons and in five distinctive morphologies in carbonate dominated members of the Late Aptian-Early Albian Crato Formation of the Araripe Basin in northeast Brazil. Some forms exhibit typical hopper-faced cubes with an outer veneer of marcasite with calcite and quartz in the centre. A second morph comprises compacted marcasite veneers exhibiting a collapsed cube morphology showing that compaction predated calcite and quartz precipitation. A third morph comprises four pointed 'stars' in a series of concentric circles, representing halite crystals that grew within the sediment and possibly tore apart a thin bacterial mat that bound the surface of the sediment. Pseudomorph size varies from 5-10 mm diameter for those replaced by several mineral phases to aggregates of up to 20 mm diameter for those replaced by silica. The presence of abundant halite pseudomorphs suggests that hypersaline waters prevailed during deposition of the Nova Olinda Member fossil Konservat Lagerstätte and were a contributing factor to the excellent preservation of its fossil assemblage.

AB - Pseudomorphs after hopper-faced halite occur at several horizons and in five distinctive morphologies in carbonate dominated members of the Late Aptian-Early Albian Crato Formation of the Araripe Basin in northeast Brazil. Some forms exhibit typical hopper-faced cubes with an outer veneer of marcasite with calcite and quartz in the centre. A second morph comprises compacted marcasite veneers exhibiting a collapsed cube morphology showing that compaction predated calcite and quartz precipitation. A third morph comprises four pointed 'stars' in a series of concentric circles, representing halite crystals that grew within the sediment and possibly tore apart a thin bacterial mat that bound the surface of the sediment. Pseudomorph size varies from 5-10 mm diameter for those replaced by several mineral phases to aggregates of up to 20 mm diameter for those replaced by silica. The presence of abundant halite pseudomorphs suggests that hypersaline waters prevailed during deposition of the Nova Olinda Member fossil Konservat Lagerstätte and were a contributing factor to the excellent preservation of its fossil assemblage.

KW - Araripe Basin

KW - Brazil

KW - Crato Formation

KW - Cretaceous

KW - Halite pseudomorphs

UR - http://www.scopus.com/inward/record.url?scp=34748818714&partnerID=8YFLogxK

U2 - 10.1016/j.cretres.2006.10.003

DO - 10.1016/j.cretres.2006.10.003

M3 - Article

AN - SCOPUS:34748818714

VL - 28

SP - 613

EP - 620

JO - Cretaceous research

JF - Cretaceous research

SN - 0195-6671

IS - 4

ER -