grant 821.01.007 A late Holocene Tephrochronology for the ... · Kees Nooren, Annika Huizinga, Wim...
1
1745 +/-135 BC 575 +/-175 BC AD 773 +/-97 AD 783 +/-96 1982 2005 2430 +/-132 BC 845 +/-51 BC 2008 0 1 0 1 2 3 4 core PP1 Pozpetr. core 336 core PP4 core 252 core 196 core 193 core 197 core 188 core 185 0 5000 10000 15000 20000 elevation (m+REF) distance (m) A late Holocene Tephrochronology for the Maya Lowlands, Central America AGU 2012 Kees Nooren, Annika Huizinga, Wim Hoek, Manfred van Bergen, Hans Middelkoop [email protected] grant 821.01.007 Acknowledgements: We are grateful to Payson Sheets for sending a TBJ tephra sample, Hans van der Plicht for the 14 C dating and INEGI (Mexico) for providing the LIDAR data. Transect A Results / Conclusions PP1 core • Initially twelve (crypto)tephralayers were identified in the PP1 core; • Major-element compositions indicate El Chichón as the source volcano; • Most notable tephra-fall occurred around 50 BC, AD 539, AD 1509 and AD 1982; only the AD 1509 tephra lacked a bipolar match to volcanic sulfur spikes in the ice core records; • El Chichón tephra-fall can be bimodal in grain size with a relative high Si-content for the coarser mode; • Individual eruption events are not easily distinguishable by major and trace element analyses. Beach ridge sequence chronology • Five beach ridge sections with increased amounts of tephra were identified during the first fieldwork campaign; • Major and trace element compositions of the large tephra glass shards are comparable to the composition of glass shards from the coarse mode of El Chichón’s ash-fall deposits found in the flood basin; • A preliminary age-distance model suggests tephra deposition after eruptions of El Chichón around 2000 BC (unit K?), 722 BC (unit I), 50 BC (unit H), AD 811 (unit D) and AD 1982 (unit A) when the Usumacinta and Grijalva rivers supplied large amounts of tephra; • The beach ridge sequence host promising new data for improving the tephrochronological framework for the Maya Lowlands. Transect B Pozpetr. Methods Tephra was extracted from the PP1 core at 1 cm resolution using heavy liquid separation. Major-element compositions of glass shards were determined for identified (crypto)tephra layers by EPMA. Trace element analyses were conducted on a few selected samples by LA-ICPMS. Twenty samples were 14 C-dated by AMS to construct an age-depth model. The high sulfur emissions accompanying El Chichón’s eruptions allowed testing of our age-depth model through a tentative correlation with volcanic sulfur peaks in ice cores from Greenland and Antarctica. The beach ridge sequence was sampled along two transects. Volcanic glass shards and pumice fragments were isolated from sand samples with increased amounts of tephra. Glass shards were analyzed by EPMA and LA- ICPMS. Six samples of terrestrial macroremains were 14 C-dated by AMS. Core PP1 252 193 + 196 188 185 PP4 Location of the PP1 core, ~140 km NE of El Chichón volcano. Core PP1 Matrix glass composition after Luhr et al. (1984), Cochemé and Silva-Mora (1983), Macías et al. (2003) and Palais et al. (1992). Photo by Annika Huizinga Photo by Annika Huizinga A: Core retrieval flood basin (location core PP4); B: Rhyolithic AD 1509 tephra (core PP4: 17 - 26 cm depth); C: Sampling of beach ridges with Van der Staay suction corer (core 197); D: Debris layer with abundant pumice and glass shards (core 193: 497 – 515 cm depth); E: Organic debris layer contain 14 C datable leaf fragments (core 185 (469 - 483 cm depth). Photo by Elise van Winden B: C: D: E: PP1 Tephrostratigraphy Major and trace element composition Beach ridge sequence chronology ♦ ■ ▲ ● ▲ ● + ● _ ◊ ♦ ∆ 1982 1509 1343 811 539 161 -50 -722 -1357 B C D E F G H I J -180 -160 -140 -120 -100 -80 -60 -40 -20 0 -2200 -1700 -1200 -700 -200 300 800 1300 1800 depth (cm) calibrated age (yr AD) AD 1509? tephra AD 1982 tephra AD 539? tephra 50 BC? tephra minerals volcanic glass + diatoms minerals + volcanic glass + diatoms organic deposits clay/ silt tephra tephra A Calibrated ages deposits B – J after Espíndola et al., 2000. Bipolar volcanic sulfur spikes after Sigl et al., in review (see also PP21B-2015, this AGU fall meeting). 2.5 3.5 4.5 5.5 11 12 13 14 15 16 17 K 2 O wt% Al 2 O 3 wt% 0 5 10 15 20 25 0 10 20 30 40 50 Zr/Y Sr/Y 0.0 0.5 1.0 1.5 2.0 2.5 69 71 73 75 77 79 CaO wt% SiO 2 wt% Ilopango TBJ tephra Matrix glass El Chichon 1982 Matrix glass El Chichon unit B AD 539 tephra (Nooren et al., 2009) AD 539 tephra (core 336) Introduction and aim The Maya Lowlands in southern Mexico, Guatemala and Belize were densely populated for thousands of years, and have been the subject of intensive studies on the interaction between humans and their environment. Accurate radiocarbon dating of proxy records and disrupting events has proved to be difficult due to the lack of organic material in many deposits and the ‘old carbon effect’ related to the calcareous geology of the Yucatan Peninsula. Tephrostratigraphy offers a unique but still unexplored method to define time markers for palynological, limnological and archaeological studies in this region, due to the frequent occurrence of tephra-fall. In this project we are developing a tephrochronology using sediment cores from a flood basin and beach ridges of the Usumacinta-Grijalva delta in southern Mexico. The tephrochronological framework will be used to establish a detailed chronological reconstruction of the formation of world’s largest late Holocene beach ridge plain. 197 -1745 -575 783 773 1982 ▲ □ ♦ Laguna Cometa PP1 Pozpetr. core 336 core PP4 ● -5 0 5 10 15 20 -23000 -18000 -13000 -8000 -3000 -6000 -5000 -4000 -3000 -2000 -1000 0 1000 2000 elevation (m+REF) distance from shoreline (m) calibrated age (yr AD) leaf fragments charcoal tephra beach ridges charcoal basal peat samples basal peat AD 539 tephra AD 1509 tephra beach ridge sand estuarine deposits beach ridge sand estuarine deposits 750 yrs. beach ridge sand estuarine deposits 1000 yrs. beach ridge sand estuarine deposits ''peat" core 252 core 193 core 196 ~3.6 m/yr ~4.8 m/yr ~2.8 m/yr ? ? core 197 2.5 3.5 4.5 5.5 11 12 13 14 15 16 17 K 2 O wt% Al 2 O 3 wt% 0 5 10 15 20 25 0 10 20 30 40 50 Zr/Y Sr/Y 0.0 0.5 1.0 1.5 2.0 2.5 69 71 73 75 77 79 CaO wt% SiO 2 wt% core 197 core 193 core 252 - 440 cm depth core 252 - 490 cm depth core Pozpetr. 88-90 cm depth
Transcript of grant 821.01.007 A late Holocene Tephrochronology for the ... · Kees Nooren, Annika Huizinga, Wim...
1745 +/-135 BC 575 +/-175 BC AD 773 +/-97AD 783 +/-96 1982 2005
2430 +/-132 BC 845 +/-51 BC 2008
0
1
0
1
2
3
4
core PP1
Pozpetr. core 336 core PP4 core 252 core 196 core 193 core 197
core 188 core 185
0 5000 10000 15000 20000
ele
va
tio
n (
m+
RE
F)
distance (m)
A late Holocene Tephrochronology for the Maya Lowlands, Central America
AGU 2012 Kees Nooren, Annika Huizinga, Wim Hoek, Manfred van Bergen, Hans Middelkoop [email protected]
grant 821.01.007
Acknowledgements: We are grateful to Payson Sheets for sending a TBJ tephra sample, Hans van der Plicht for the 14C dating and INEGI (Mexico) for providing the LIDAR data.
Transect A
197
Results / Conclusions PP1 core
• Initially twelve (crypto)tephralayers were identified in the PP1 core;
• Major-element compositions indicate El Chichón as the source volcano;
• Most notable tephra-fall occurred around 50 BC, AD 539, AD 1509 and AD 1982; only the AD 1509 tephra lacked a bipolar match to volcanic sulfur spikes in the ice core records;
• El Chichón tephra-fall can be bimodal in grain size with a relative high Si-content for the coarser mode;
• Individual eruption events are not easily distinguishable by major and trace element analyses.
Beach ridge sequence chronology
• Five beach ridge sections with increased amounts of tephra were identified during the first fieldwork campaign;
• Major and trace element compositions of the large tephra glass shards are comparable to the composition of glass shards from the coarse mode of El Chichón’s ash-fall deposits found in the flood basin;
• A preliminary age-distance model suggests tephra deposition after eruptions of El Chichón around 2000 BC (unit K?), 722 BC (unit I), 50 BC (unit H), AD 811 (unit D) and AD 1982 (unit A) when the Usumacinta and Grijalva rivers supplied large amounts of tephra;
• The beach ridge sequence host promising new data for improving the tephrochronological framework for the Maya Lowlands.
Transect B
Pozpetr.
Methods Tephra was extracted from the PP1 core at 1 cm resolution using heavy liquid separation. Major-element compositions of glass shards were determined for identified (crypto)tephra layers by EPMA. Trace element analyses were conducted on a few selected samples by LA-ICPMS. Twenty samples were 14C-dated by AMS to construct an age-depth model. The high sulfur emissions accompanying El Chichón’s eruptions allowed testing of our age-depth model through a tentative correlation with volcanic sulfur peaks in ice cores from Greenland and Antarctica.
The beach ridge sequence was sampled along two transects. Volcanic glass shards and pumice fragments were isolated from sand samples with increased amounts of tephra. Glass shards were analyzed by EPMA and LA-ICPMS. Six samples of terrestrial macroremains were 14C-dated by AMS.
Core PP1
252
193 + 196
188
185
A:
PP4
Location of the PP1 core, ~140 km NE of El Chichón volcano.
Core PP1
Matrix glass composition after Luhr et al. (1984), Cochemé and Silva-Mora (1983), Macías et al. (2003) and Palais et al. (1992).
Photo by Annika Huizinga Photo by Annika Huizinga
A: Core retrieval flood basin (location core PP4);
B: Rhyolithic AD 1509 tephra (core PP4: 17 - 26 cm depth);
C: Sampling of beach ridges with Van der Staay suction corer (core 197);
D: Debris layer with abundant pumice and glass shards (core 193: 497 – 515 cm depth);
E: Organic debris layer contain 14C datable leaf fragments (core 185 (469 - 483 cm depth).
Photo by Elise
van Winden
B: C: D: E:
PP1 Tephrostratigraphy Major and trace element composition Beach ridge sequence chronology
♦
■
▲
●
▲
●
+
●
_
◊
♦
∆
1982
1509
1343
811
539
161
-50
-722
-1357
B
C
D
E
F
G
H
I
J
-180
-160
-140
-120
-100
-80
-60
-40
-20
0
-2200 -1700 -1200 -700 -200 300 800 1300 1800
de
pth
(c
m)
calibrated age (yr AD)
AD 1509? tephra
AD 1982 tephra
AD 539? tephra
50 BC? tephra
min
era
ls
vo
lcan
ic g
lass +
d
iato
ms
min
era
ls +
vo
lcan
ic
gla
ss
+ d
iato
ms
org
anic
de
po
sits
clay/silt
tephra
tephra
A
Calibrated ages deposits B – J after Espíndola et al., 2000. Bipolar volcanic sulfur spikes after Sigl et al., in review (see also PP21B-2015, this AGU fall meeting).
2.5
3.5
4.5
5.5
11 12 13 14 15 16 17
K2O
wt%
Al2O3 wt%
0
5
10
15
20
25
0 10 20 30 40 50
Zr/Y
Sr/Y
0.0
0.5
1.0
1.5
2.0
2.5
69 71 73 75 77 79
CaO
wt%
SiO2 wt%
Ilopango TBJ tephra
Matrix glass El Chichon 1982
Matrix glass El Chichon unit B
AD 539 tephra (Nooren et al., 2009)
AD 539 tephra (core 336)
Introduction and aim The Maya Lowlands in southern Mexico, Guatemala and Belize were densely populated for thousands of years, and have been the subject of intensive studies on the interaction between humans and their environment. Accurate radiocarbon dating of proxy records and disrupting events has proved to be difficult due to the lack of organic material in many deposits and the ‘old carbon effect’ related to the calcareous geology of the Yucatan Peninsula.
Tephrostratigraphy offers a unique but still unexplored method to define time markers for palynological, limnological and archaeological studies in this region, due to the frequent occurrence of tephra-fall.
In this project we are developing a tephrochronology using sediment cores from a flood basin and beach ridges of the Usumacinta-Grijalva delta in southern Mexico. The tephrochronological framework will be used to establish a detailed chronological reconstruction of the formation of world’s largest late Holocene beach ridge plain.
197
-1745
-575
783
773
1982
▲
□
♦
Laguna Cometa
PP1
Pozpetr.
core 336
core PP4
●
-5 0 5 10 15 20
-23000
-18000
-13000
-8000
-3000
-6000 -5000 -4000 -3000 -2000 -1000 0 1000 2000
elevation (m+REF)
dis
tan
ce fro
m
sh
ore
line
(m)
calibrated age (yr AD)
leaf fragments
charcoal
tephra beach ridges
charcoal basal peat
samples
basal peat
AD 539 tephra
AD 1509 tephra
beach
ridge san
d
estuarin
ed
epo
sits
beach
ridge san
d
estuarin
ed
epo
sits
750 yrs.
beach
ridge san
d
estuarin
ed
epo
sits
1000 yrs.
beach
ridge san
destu
arine
dep
osits
''peat"
core 252
core 193
core 196
~3.6 m/yr
~4.8 m/yr
~2.8 m/yr
??
core 197
2.5
3.5
4.5
5.5
11 12 13 14 15 16 17
K2O
wt%
Al2O3 wt%
0
5
10
15
20
25
0 10 20 30 40 50
Zr/Y
Sr/Y
0.0
0.5
1.0
1.5
2.0
2.5
69 71 73 75 77 79
CaO
wt%
SiO2 wt%
core 197
core 193
core 252 - 440 cm depth
core 252 - 490 cm depth
core Pozpetr. 88-90 cm depth
