28
H. Khozyem
dominant archosaurs, whereas in the marine environment were dominated the nonarchosaurian diapsids. This event was coincident with the opening the central Atlantic
magmatic province [9, 70, 71] as well as the large Manicouagan impact (Fig. 3). Its
characterized by perturbation in the carbon cycle with increasing of CO 2 level reached
about 1300–2200 ppm that causes the rising extreme warming conditions.
4.5 Cretaceous-Tertiary Mass Extinction
The KPg boundary is placed around 66 Ma and is considered as the 2nd largest mass
extinction event in the earth’s history. About 17% of all families, 50% of all genera and
75% of all species became extinct [72]. this event is characterized by: a- presence of
extraterritorial Iridium anomaly associated with red clay layer; b-Mass Extinction of
planktic foraminifera at the KPB followed by evolutionary trend of Danian species;
c- negative shift in δ
13 C due to increased atmospheric CO 2 level [73–76]. Chicxulub
impact was the acceptable scenario that proposed to explain this event; [77–86].
Recently several studies focused on the relation between Deccan volcanism eruption
and the KPB Mass Extinction event [87, 88, 37, 89, 90, 91, 92, 38, 93, 94, 95].
5 Hyperthermal Events
During the last 65 million years, the Earth has undergone many episodes of natural
global warming and cooling due to various causes. The sedimentary rocks hold a good
record of the environmental changes during this part of Earth’s history. Most of these
environmental changes are linked to carbon cycle perturbations that resulted in the
increase or decrease in Earth’s temperature linked to variations between extremes of
expansive warmth with ice-free poles to extremes of cold with massive continental
ice-sheets and polar ice caps. Such extreme climatic changes are controlled on a
global scale by Earth’s orbital geometry and/or plate tectonics [96].
The Eocene (55.8 ± 0.2 to 33.9 ± 0.1 Ma. [11], is a period in Earth history characterized by climatic extremes varying from the greenhouse to icehouse conditions
(Fig. 4). The warmest period of the Cenozoic era coincides with an extreme warming
event at the Paleocene-Eocene transition known as Paleocene-Eocene Thermal Maximum (ETM1 or PETM) [97]. The climate warmed steadily until the Early Eocene
Climatic Optimum (EECO) ~53.5 Ma when temperatures and greenhouse gas concentrations peaked at their maxima for ~1.5 myr [98]. These two major events are
followed by several abrupt and short hyperthermal events including H2 (53.6 Ma),
I1 (53.3 Ma), I2 (53.2 Ma) and ETM-3 (52.8 Ma) [98]. A major negative δ
13 C org
excursion marks each of these hyperthermal events (Fig. 4)
The most recognizable amongst these warming events is the Paleocene-Eocene
Thermal Maximum (PETM), which was first recognized [99] in the Ocean Drilling
Program (ODP) site 690B cores, and associated with a temperature rise of 5–9 °C
H. Khozyem
dominant archosaurs, whereas in the marine environment were dominated the nonarchosaurian diapsids. This event was coincident with the opening the central Atlantic
magmatic province [9, 70, 71] as well as the large Manicouagan impact (Fig. 3). Its
characterized by perturbation in the carbon cycle with increasing of CO 2 level reached
about 1300–2200 ppm that causes the rising extreme warming conditions.
4.5 Cretaceous-Tertiary Mass Extinction
The KPg boundary is placed around 66 Ma and is considered as the 2nd largest mass
extinction event in the earth’s history. About 17% of all families, 50% of all genera and
75% of all species became extinct [72]. this event is characterized by: a- presence of
extraterritorial Iridium anomaly associated with red clay layer; b-Mass Extinction of
planktic foraminifera at the KPB followed by evolutionary trend of Danian species;
c- negative shift in δ
13 C due to increased atmospheric CO 2 level [73–76]. Chicxulub
impact was the acceptable scenario that proposed to explain this event; [77–86].
Recently several studies focused on the relation between Deccan volcanism eruption
and the KPB Mass Extinction event [87, 88, 37, 89, 90, 91, 92, 38, 93, 94, 95].
5 Hyperthermal Events
During the last 65 million years, the Earth has undergone many episodes of natural
global warming and cooling due to various causes. The sedimentary rocks hold a good
record of the environmental changes during this part of Earth’s history. Most of these
environmental changes are linked to carbon cycle perturbations that resulted in the
increase or decrease in Earth’s temperature linked to variations between extremes of
expansive warmth with ice-free poles to extremes of cold with massive continental
ice-sheets and polar ice caps. Such extreme climatic changes are controlled on a
global scale by Earth’s orbital geometry and/or plate tectonics [96].
The Eocene (55.8 ± 0.2 to 33.9 ± 0.1 Ma. [11], is a period in Earth history characterized by climatic extremes varying from the greenhouse to icehouse conditions
(Fig. 4). The warmest period of the Cenozoic era coincides with an extreme warming
event at the Paleocene-Eocene transition known as Paleocene-Eocene Thermal Maximum (ETM1 or PETM) [97]. The climate warmed steadily until the Early Eocene
Climatic Optimum (EECO) ~53.5 Ma when temperatures and greenhouse gas concentrations peaked at their maxima for ~1.5 myr [98]. These two major events are
followed by several abrupt and short hyperthermal events including H2 (53.6 Ma),
I1 (53.3 Ma), I2 (53.2 Ma) and ETM-3 (52.8 Ma) [98]. A major negative δ
13 C org
excursion marks each of these hyperthermal events (Fig. 4)
The most recognizable amongst these warming events is the Paleocene-Eocene
Thermal Maximum (PETM), which was first recognized [99] in the Ocean Drilling
Program (ODP) site 690B cores, and associated with a temperature rise of 5–9 °C