Sat Mar 23, 2024 11:33 pm by globalturbo
Scientists link rapid geomagnetic field reversal, climate change, and supervolcanic eruptions to same geological time period
Posted on October 17, 2012
October 17, 2012 – GEOLOGY - An
extremely brief reversal of the geomagnetic field, climate variability
and a supervolcanic eruption. 41,000 years ago, a complete and rapid
reversal of the geomagnetic field occurred. Magnetic studies of the GFZ
German Research Centre for Geosciences on sediment cores from the Black
Sea show that during this period, during the last ice age, a compass at
the Black Sea would have pointed to the south instead of north.
Moreover, data obtained by the research team formed around GFZ
researchers Dr. Norbert Nowaczyk and Prof. Helge Arz, together with
additional data from other studies in the North Atlantic, the South
Pacific and Hawaii, prove that this polarity reversal was a global
event. Their results are published in the latest issue of the scientific
journal “Earth and Planetary Science Letters.” What is
remarkable is the speed of the reversal: “The field geometry of reversed
polarity, with field lines pointing into the opposite direction when
compared to today’s configuration, lasted for only about 440 years, and
it was associated with a field strength that was only one quarter of
today’s field,” explains Norbert Nowaczyk. “The actual polarity changes
lasted only 250 years. In terms of geological time scales, that is very
fast.” During this period, the field was even weaker, with only 5% of
today’s field strength. As a consequence, the Earth nearly completely
lost its protection shield against hard cosmic rays, leading to a
significantly increased radiation exposure. This is documented by peaks
of radioactive beryllium (10Be) in ice cores from this time, recovered
from the Greenland ice sheet. 10Be as well as radioactive carbon (14C)
is caused by the collision of high-energy protons from space with atoms
of the atmosphere. The polarity reversal now found with the
magnetisation of Black Sea sediments has already been known for 45
years. It was first discovered after the analysis of the magnetisation
of several lava flows near the village Laschamp near Clermont-Ferrand in
the Massif Central, which differed significantly from today’s direction
of the geomagnetic field. Since then, this geomagnetic feature is known
as the ‘Laschamp event.’ However, the data of the Massif Central
represent only some point readings of the geomagnetic field during the
last ice age, whereas the new data from the Black Sea give a complete
image of geomagnetic field variability at a high temporal resolution.
Besides giving evidence for a geomagnetic field reversal 41,000 years
ago, the geoscientists from Potsdam discovered numerous abrupt climate
changes during the last ice age in the analyzed cores from the Black
Sea, as it was already known from the Greenland ice cores. This
ultimately allowed a high precision synchronization of the two data
records from the Black Sea and Greenland. The largest volcanic eruption
on the Northern hemisphere in the past 100 000 years, namely the
eruption of the super volcano 39400 years ago in the area of today’s
Phlegraean Fields near Naples, Italy, is also documented within the
studied sediments from the Black Sea. The ashes of this eruption, during
which about 350 cubic kilometers of rock and lava were ejected, were
distributed over the entire eastern Mediterranean and up to central
Russia. These three extreme scenarios, a short and fast reversal of the
Earth’s magnetic field, short-term climate variability of the last ice
age and the volcanic eruption in Italy, have been investigated for the
first time in a single geological archive and placed in precise
chronological order. –Science Codex
Thanks to: http://theextinctionprotocol.wordpress.com
Posted on October 17, 2012
extremely brief reversal of the geomagnetic field, climate variability
and a supervolcanic eruption. 41,000 years ago, a complete and rapid
reversal of the geomagnetic field occurred. Magnetic studies of the GFZ
German Research Centre for Geosciences on sediment cores from the Black
Sea show that during this period, during the last ice age, a compass at
the Black Sea would have pointed to the south instead of north.
Moreover, data obtained by the research team formed around GFZ
researchers Dr. Norbert Nowaczyk and Prof. Helge Arz, together with
additional data from other studies in the North Atlantic, the South
Pacific and Hawaii, prove that this polarity reversal was a global
event. Their results are published in the latest issue of the scientific
journal “Earth and Planetary Science Letters.” What is
remarkable is the speed of the reversal: “The field geometry of reversed
polarity, with field lines pointing into the opposite direction when
compared to today’s configuration, lasted for only about 440 years, and
it was associated with a field strength that was only one quarter of
today’s field,” explains Norbert Nowaczyk. “The actual polarity changes
lasted only 250 years. In terms of geological time scales, that is very
fast.” During this period, the field was even weaker, with only 5% of
today’s field strength. As a consequence, the Earth nearly completely
lost its protection shield against hard cosmic rays, leading to a
significantly increased radiation exposure. This is documented by peaks
of radioactive beryllium (10Be) in ice cores from this time, recovered
from the Greenland ice sheet. 10Be as well as radioactive carbon (14C)
is caused by the collision of high-energy protons from space with atoms
of the atmosphere. The polarity reversal now found with the
magnetisation of Black Sea sediments has already been known for 45
years. It was first discovered after the analysis of the magnetisation
of several lava flows near the village Laschamp near Clermont-Ferrand in
the Massif Central, which differed significantly from today’s direction
of the geomagnetic field. Since then, this geomagnetic feature is known
as the ‘Laschamp event.’ However, the data of the Massif Central
represent only some point readings of the geomagnetic field during the
last ice age, whereas the new data from the Black Sea give a complete
image of geomagnetic field variability at a high temporal resolution.
Besides giving evidence for a geomagnetic field reversal 41,000 years
ago, the geoscientists from Potsdam discovered numerous abrupt climate
changes during the last ice age in the analyzed cores from the Black
Sea, as it was already known from the Greenland ice cores. This
ultimately allowed a high precision synchronization of the two data
records from the Black Sea and Greenland. The largest volcanic eruption
on the Northern hemisphere in the past 100 000 years, namely the
eruption of the super volcano 39400 years ago in the area of today’s
Phlegraean Fields near Naples, Italy, is also documented within the
studied sediments from the Black Sea. The ashes of this eruption, during
which about 350 cubic kilometers of rock and lava were ejected, were
distributed over the entire eastern Mediterranean and up to central
Russia. These three extreme scenarios, a short and fast reversal of the
Earth’s magnetic field, short-term climate variability of the last ice
age and the volcanic eruption in Italy, have been investigated for the
first time in a single geological archive and placed in precise
chronological order. –Science Codex
Thanks to: http://theextinctionprotocol.wordpress.com
