KB 03.1 | SAHRIS

General

Object Auto ID

65948

Quantity

1.00

Object Description

This sample comes from the stalagmite found at Kromdraai B. It is ca. 15 cm long.

Provenance

Kromdraai B (Unit P), Cradle of Humankind, Gauteng.

Description

Material Types

Flowstone

Technique Types

Cutting

Measurement Type	Unit	Value
Length	cm	15.00	View

Dimension Comments

Since the object underwent destructive chemical analysis, it is no longer found in a single piece but in six pieces with the following masses: 1) 13.6g 2) 26.36g 3) 10.85g 4) 91.86g 5) 17.02g 6) 25.63g.

History

Object Age

2009

Object Age Comment

2009 is the year when the sample was cut off an in situ Pleistocene stalagmite.

Geological Period

Pleistocene

Object User

Vincent Balter

User Comment

Since 2009, sample KB 03.1 has been securely kept in Lyon, France, for U-Pb dating to obtain a minimum age for Unit P at Kromdraai. This requires a destructive analysis involving the following steps:
Pulverizing the sample in a mortar.
Cleaning by leaching with cold 0.1 mol/L acetic acid.
Dissolving the sample in 4.5 mol/L HNO3.
Measuring REE abundance and the 238U/206Pb ratio on a quadrupole ICP-MS, using In as an internal standard.
Extracting U on anion exchange resin; the matrix is eluted with 9 mol/L HCl, and U with 0.1 mol/L HCl. Measuring the 234U/238U ratio on a multi-collector ICP-MS, using standard (NIST) bracketing to correct instrumental drift.
Extracting Pb on anion exchange resin; the matrix is eluted with 1 mol/L HBr, and Pb with 6 mol/L HCl. Measuring Pb isotope composition on a multi-collector ICP-MS, using Tl doping to correct mass-dependent instrumental isotope fractionation and standard (NIST) bracketing to correct instrumental drift.

Collector

Jose Braga

Vincent Balter

Collector Comment

When sample KB 03.1 was exported to France for destructive analysis, it was understood, after discussions with Francis Thackeray and Stephany Potze (formerly curator at the former Transvaal Museum, now Ditsong National Museum of Natural History), that a letter of permission from Stephany Potze was needed. In 2009, Francis Thackeray moved from the Ditsong National Museum of Natural History to the Institute for Human Evolution (IHE) at the University of the Witwatersrand (Wits). The correspondence sent to Francis Thackeray by Stephany Potze would likely have been sent electronically to Wits. Unfortunately, Francis Thackeray no longer has this correspondence, having retired from Wits in December 2017, and neither José Braga nor Vincent Balter kept this correspondence.