LAND SEA CORRELATIONS: PITFALLS AND REMEDIES

ASHOK KUMAR SINGHVI Physical Research Laboratory

Ahmedabad, India

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Geo-science: The Basic Science for a Sustainable Future

INTERNATIONAL GEOLOGICAL CONGRESS DELHI, FEB 23-29, 2020

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Issues 1. Are LAND – SEA and LAND-LAND correlations Correct

2. Are the inferred periodicities in terrestrial records correct

3. Are proxies interpreted along with their response times/thresholds

4. Are tele-connections correct, sensu stricto

5. Do we understand land records their climatic implications

Do we really have

Secured Chronologies and Proxy interpretations for model validations ?

Stating the Obvious & Overstating it to Ensure Caution

LAND SEA CORRELATIONS: PITFALL AND REMEDIES

Geological Correlation using tuning are like Seven-league boots approach of Near Instant travel (Response) over long distances.

But this does not happen in nature. Using these one is lead to a trap of a

“Coherent Myth” or “Reinforcment syndrome” Oldfield2001,Blaauw, 2012

Would the paleoclimate science not be boring, should this be so

Kilimanjaro : a case

Earth Science Reviews 2001

Quaternary Science Reviews 2012

Precise Age Precise Variable

Age with Error Variable with error Threshold + lags + Variable response time

Precise Age Variable with Error

Serious ISSUES on both CHRONOLOGY AND PROXIES

Chronologies on terrestrial sequences are based on:

Radiocarbon Range ~40ka, precision ⇑, calibration, organics, diagenesis, contamination, reservoir ages variable with in a lake, sample-strata correlation, Uranium Series Range 300ka, no calibration, precision ⇑, pure carbonate phases, detrital contamination reduces precision and accuracy

Cosmogenic Isotopes Range ~ Few ka-Ma, needs inputs on irradiation geometry and constancy of the same, not good for accreting soft sediments

Luminescence Dating Range Present –few hundred ka –Ma, sample –strata correlation clean, precision ~ 5%

Paleomagnetism Relative dating

Records tuned with MIS or GRIP or orbital – Double tuning for terrestrial records

Mischke et al, 2013 (in press)

Intra Lake Variability In radiocarbon Reservoir ages And Its variability with time

Proxies Grain size

Carbonates Magnetic Susceptibility

Stable isotopes diatoms

Foraminifera Geochemical changes Pollen Phytoliths Alkenones ………

In tuning the proxy records, It is implicitly assumed that all respond to a Global forcing instantaneously and remain in phase, and that their response has been time invariant, without any thresholds. In contrast,

NULL HYPOTHESIS : PROXIES ARE NOT CORRELATED Why should Solar Forcing be seen in records;

Each record should have a independently distilled response

Sucking In

Smearing out

Tie Point ↔ 5-10ka

Time Lines

Loess-Paleosol sequences

Kukla, 1986

Xifeng, China Magnetic Susceptibility

tuned to oceanic record

Maher and Thomson, 1992

“…extremely high correlation with the standard 18O record” S

PE

CM

AP

TIM

E S

CA

LE X

1000

yea

rs

18δO Log Susceptibility Luochuan

S1

S2

Loess –Paleosol sequences Considered to be the terrestrial analogs of marine records

Vandenberghe et al., 1997 U ratio – 44-16µm/16-5µm

Grain Size records also seen to be covariant

Porter and An. Science

Deduction of Milankovitch periodicities based on Ages assignments using inferred ages for the loess/paleosol layers

Some of the Obvious Difficulties B/M boundary : In Marine Records is in Stage 19 (warmer), but in loess layer L8 (cooler) - missing time!

Freezing time of magnetization in loess – few ka ? what is being correlated

In Alaska, Magnetic susceptibility is out of phase with China (high in loess and low in paleosols) Grain-size vs. Soil phase lagged Singhvi et al., Earth Sci. Revs,2001

Zhao and Schakelton, EPSL,1999

Grain Size

Carbonate content 0.8m 5-10 ka Vandenberghe, 2012

EPISODIC ACCUMULATION & LONG HIATUSES

EPISODIC ACCUMULATION & LONG HIATUSES

Stevens – INQUA 2011 How does one compare these with Ocean and Ice cores with constant accumulation rates ?

S0 Loess-Soil

S1 Soil-Loess

Drier- Wetter

So

S1 In Xian Soil till 75ka

Soil

Soil

Soil

Singhvi et al. Earth Sci Revs

Ashok Singhvi DESERTS

Limits of Active dunes at LGM, Holocene and Present

Sarnthein ,1982 Synchronous expansion and contraction

ALBEDO CHANGES IN THE PASTPAST

330mm/a 200mm/a

Singhvi etal QSR; Dhir et al JASc

Aeolian system Response Phase Lagged and Episodic

We see a preservation record And not An aggradation/dynamism record

Age of linear dunes

Majority of data is by PRL and this data shows that different deserts responded differently.

Aeolian aggradation in Deserts was not synchronous -peaking at LGM

LGM India

Modified after Lancaster, 2004

Limits of Active dunes at LGM, Holocene and Present

Sarnthein ,1982

Synchronous expansion and contraction

Not tenable – needs a change

0 200

Km

SutlejRavi

Indu

s R

SULAIMAN RANGE

ALLUVIAL FANS OF HIMALAYAN RIVERS

Sabarmat R

.

Ganga R

Jamuna R

DELHI

KUTCH

SAURASHTRA

AHMEDABAD

30O

90O

30O

76O70O

KARACHI

10ka

5ka

4ka

3ka

1ka

Dune Sand (Thar)Southern Desert MarginMarshy area (Rann)

SEMI-ARIDARID

ARABIAN SEA Progressive SHIFTING OF Active Dune limits From 10 to 1ka.

Shrinking Desert

800a 400a

Active/Fossil Dune Limit

Juyal et al. 2006

ka B.P.

0

4

8

12

16

20

LEGEND

West (<200 mm) East (330 mm)

Thar Desert

12

6

4.8

7

9.4

12

4.5

7

21

North-west (250 mm)

Ephemeral (present condition)

Lake high

Fluctuating with extremes

Fluctuating without extremes

Hypersaline

(Kanod and Bap-Malar) (Lunkaransar) (Didwana)

10

15.5

East (500 mm)

(Sambhar)

4.5

7-8

Fluvially reworked

aeolian sediments

10

15.5

Fluvially reworked

aeolian sediments

3.5

Spatial Heterogeneity of records- MONSOON VARIED DURING THE HOLOCENE

• >9ka -7ka • 7ka - 4.8ka

• < 4.5 ka

400km

THAR DESERT

(Roy et al,2009)

From RC-2735 box cores

Composite

Temperature variationG. Bulloides

From RC-2730 box cores

Anderson et al., 2002

Sple

othe

m re

cord

Floo

d re

cord

(Lun

i R)

Dun

e re

cord

2500

2250

2000

1750

1500

1250

1000

800

600

500

450

400

350

300

250

200

150

100

50

Bre

aded

seq

uenc

e

Ove

rban

k an

d flo

od s

eque

nce

Pond

seq

uenc

e

Aeo

lian

sand

Pond

seq

uenc

eFl

ood

plai

n

Wet humid

Fluctuating

Fluctuating

Semi- arid

Arid/Semi arid

Semi- arid

Semi- arid

Wet Humid

Semi-arid

Year

BP

0

500

400

300

200

100

0

1000

800

600

6 4 2 0

(1) Yadav and Ramesh, 2001(2) Anderson et al, 2003

(1)

(2)

(Yea

r BP)

Monsoon Winds And G Bulloides ; Vs. Spatial Heterogeneity of Rainfall

Kocurek, 1999

Creation of a terrestrial sedimentary record in non-trivial

My submission (possibly obvious to many)

• Creation of Sedimentary record on land needs a Window of Opportunity based on Sediment Supply, Transport and Preservation

• Sediment supply in terrestrial domain is invariably, variable • Preservation in transitional climates. Only the Preserved Record seen. • Spatial variability: Local vs. regional factors; Chronology • In correlations, response time of proxy is necessary; mostly ignored • Causal mechanism for correlation between land – ice and land – sea

is needed ? Why should changes in marine forams or grain size in loess be synchronous ?

• Secured chronology should only basis- role of systematic errors (reservoir ages), base lines.

Need to Revisit All records where correlations and periodicities

are established WITHOUT due recognition of CAUSAL mechanism and DETAILED chronology

THIS IS

AN INCONVENIENT TRUTH

Systems Dynamics Approach Stocks and Flows with feedbacks and delays

Xiaojing Zheng, 2011, Wasson ,2012

Needs to relook at Proxy Response- thresholds and time scales Improve Chronologies – methods and what is being dated For realistic Future EARTH scenarios

First, Get your facts straight, and then,

You can twist them as much as you want.. Mark Twain

Nature is complex and will keep its secrets

THANKS, I rest my case here.

Realizing these limitations of reason and scientific method…

it is better to understand a part of truth and apply it in our lives,

than to understand nothing at all and flounder helplessly…

“There is no visible limit to the advance of science…”