Early Cretaceous

System/
Period
Series/
Epoch
Stage/
Age
Age (Ma)
PaleogenePaleoceneDanianyounger
CretaceousUpper/
Late
Maastrichtian66.072.1
Campanian72.183.6
Santonian83.686.3
Coniacian86.389.8
Turonian89.893.9
Cenomanian93.9100.5
Lower/
Early
Albian100.5~113.0
Aptian~113.0~125.0
Barremian~125.0~129.4
Hauterivian~129.4~132.9
Valanginian~132.9~139.8
Berriasian~139.8~145.0
JurassicUpper/
Late
Tithonianolder
Subdivision of the Cretaceous system
according to the ICS, as of 2017.[1]

The Early Cretaceous (geochronological name) or the Lower Cretaceous (chronostratigraphic name), is the earlier or lower of the two major divisions of the Cretaceous. It is usually considered to stretch from 146 Ma to 100 Ma.

Geology

Proposals for the exact age of the Barremian-Aptian boundary ranged from 126 to 117 Ma until recently (as of 2019), but based on drillholes in Svalbard the defining early Aptian Oceanic Anoxic Event 1a (OAE1a) was carbon isotope dated to 123.1±0.3 Ma, limiting the possible range for the boundary to c. 121–122 Ma. There is a possible link between this anoxic event and a series of Early Cretaceous large igneous provinces (LIP).[2]

The Ontong Java-Manihiki-Hikurangi large igneous province, emplaced in the South Pacific at c. 120 Ma, is by far the largest LIP in earth's history.[3] The Ontong Java Plateau today covers an area of 1,860,000 km². In the Indian Ocean another LIP began to form at c. 120 Ma, the Kerguelen Plateau-Broken Ridge together covering 2,300,000 km².[4] Another LIP on the Liaodong Peninsula, China, c. 131–117 Ma lasted for 10 million years. It was the result of the subduction of the Kula and Pacific plates, which was probably caused by a superplume.[5]

During the opening of the South Atlantic the Paraná–Etendeka LIP produced 1.5 million km³ of basalts and rhyolites per year beginning 133 Ma and lasting for a million years.[6]

The opening of the Central Atlantic continued as the Mid-Atlantic Ridge spread north to separate the Iberian Peninsula from the banks of Newfoundland and connect to the Canada Basin in the Arctic Ocean. With the opening of the Labrador Sea Greenland became a separate tectonic plate and Laurentia became North America. The Proto-Caribbean Sea continued to grow and the Paraná-Etendeka LIP began to break Africa into three pieces. The Falkland Plateau broke-up from southern Africa at 132 Ma and Madagascar ceased to move independently c. 120 Ma. In the Panthalassic Ocean the Pacific Plate continued to grow; the Arctic Alaska-Chukotka terrane formed the Bering Strait. Continued rifting opened new basins in the Indian Ocean, separating India, Antarctica, and Australia.[7]

By 110 Ma the Mid-Atlantic Ridge reached south into the Proto-Caribbean and South Atlantic, effectively separating South America from Africa, and continued rifting in the northern end completed the longitudinal extent of the Atlantic. In Panthalassa the Ontong-Java Mega-LIP resulted in the formation of new tectonic plates and in the Indian Ocean the Kerguelen LIP began to push India northward.[8]

Other Languages
čeština: Spodní křída
한국어: 백악기 전기
magyar: Kora kréta
norsk nynorsk: Tidleg krit
português: Cretáceo Inferior
русский: Нижний мел
Simple English: Lower Cretaceous
srpskohrvatski / српскохрватски: Donja kreda
svenska: Äldre krita
українська: Рання крейда
Tiếng Việt: Phấn Trắng sớm