Английская Википедия:Hart Mine Formation

Материал из Онлайн справочника
Перейти к навигацииПерейти к поиску

Шаблон:Use American English Шаблон:Short description Шаблон:Infobox rockunit

The Hart Mine Formation is a geologic formation controversially definedШаблон:SfnШаблон:SfnШаблон:SfnШаблон:SfnШаблон:Sfn from exposures in south-central New Mexico. It preserves fossils dating back to the Eocene epoch.Шаблон:Sfn

Description

The formation is mostly calcareous reddish-brown siltstone, which makes up 72% of the type section. The remainder is mostly conglomerate with only minor silty mudstone. The conglomerate is primarily Paleozoic limestone with lesser amounts of granite. Total thickness is estimated at Шаблон:Convert. The formation lies disconformably on Crevasse Canyon Formation and grades above into the Spears Formation.Шаблон:Sfn

The formation provides evidence for a pulse of Laramide deformation in New Mexico 50 million years ago.Шаблон:Sfn

Fossils

The formation contains fossils of turtles, the lizard Glyptosaurus, the brontothere Telmatherium manteoceras, the rodent Reithroparamys huerfanensis, the insectivore Leptotomus parvus, the equid Orohippus pumilis, and the primate Notharctus tenebrosus, pointing to a Bridgerian age for the formation.Шаблон:SfnШаблон:Sfn

History of investigation

The formation was first defined by Spencer G. Lucas and Thomas E. Williamson in 1993 and named for the Hart Mine, an abandoned coal mine. The beds were formerly assigned to the Baca Formation but show differences in lithology and appear to have been deposited in a different sedimentary basin.Шаблон:Sfn However, the reassignment was disputed by Cather and collaborators, who argued that the lithological distinction is not great and the basin reconstruction was still speculative.Шаблон:Sfn Lucas responded in turn that the Hart Mine Formation has more abundant conglomerate than the Baca Formation and argued that this makes it lithologically distinct.Шаблон:SfnШаблон:Sfn However, the reassignment continues to be controversial.Шаблон:SfnШаблон:Sfn

See also

Шаблон:Portal

Footnotes

Шаблон:Reflist

References