On the Treatment of Concordant Uranium-Lead Ages

Z-WAVE INCLUSION 1. Install batteries and bring the 4-in-1 sensor within direct range of your Z-Wave gateway controller 2. Put your Z-Wave controller in inclusion mode 3. Press and release the Z-Wave button TWICE quickly 4. A new 4-in-1 sensor should appear on your controller's device list Troubleshooting Tips If you are unable to include the Z-Wave sensor to your controller, please try one of the following: Bring the 4-in-1 sensor closer to your ZWave controller Press and release the Z-Wave button quickly several times once you put the controller in the inclusion mode to ensure the command has gone through Put your controller in EXCLUSION mode and press and release the Z-Wave button TWICE quickly, then try adding it to your network again Make sure you are clicking the Z-Wave button located in the small opening on the bottom of the sensor and NOT the tamper switch located above the battery slot Z-WAVE EXCLUSION 1. Bring the 4-in-1 sensor within direct range of your Z-Wave gateway controller 2. Put your Z-Wave controller in exclusion mode 3. Press and release the Z-Wave button TWICE quickly 4. The device should disappear from your controller's device list. The LED indicator will flash 3 times when you take the batteries out and put them back in to indicate the device has been successfully excluded. Please repeat the process following all steps carefully if the LED indicator blinks only once when you re-insert the batteries.

User's Manual for

The statistical distribution of the mean squared weighted deviation. Comment on isochrons, errorchrons, and the use of MSWD-values. Author reply

The probability distribution of the mean squared weighted deviation (MSWD) is derived and its dependence on degrees of freedom f is shown. The expectation (or mean) value of MSWD=1 and is not a function of f. However, the +1σ range of the expectation value of the MSWD decreases with increasing f. The standard deviation of the MSWD is σ = ±(2/f)1/2. If MSWD 1+2(2/f)1/2, there is only <5% probability that the data define an isochron. Use of MSWD as a criterion for accepting or rejecting the assumption of an isochron may be applied only if analytical errors σxi and σyi are well known.

The statistical distribution of the mean squared weighted deviation

An increasing number of scientists recognize the value of speleothems1 as often extremely well-preserved archives of information about past climate, vegetation, hydrology, sea level, nuclide migration, water-rock interaction, landscape evolution, tectonics and human action. Well-constrained data are required to document past changes, reconstruct past patterns and predict future responses of the Earth system at a wide range of spatial and temporal scales. Speleothems are particularly useful in this regard because they can be found in many locations of the globe, sampled at high-resolution and reliably dated using high-precision uranium-series techniques.



Speleothems are bodies of mineral material formed in caves as the result of chemical precipitation from groundwater flowing or dripping in a cave. Most speleothems are composed of calcite formed by slow degassing of CO2 from supersaturated groundwater, but aragonite and gypsum forms are also common, particularly near cave entrances where evaporative effects are important. A host of different speleothem types decorate the walls, ceilings and floors of caves, and their mineralogy and morphology is a function of fluid flow and chemistry of waters feeding a particular location as well as the ambient conditions (temperature, chemistry, light) in the air or water-filled void. Subaerial forms include the familiar stalagmites, stalactites, draperies, flowstones. Subaqueous forms include rimstone pools, “rafts,” mammillary calcite wall-coatings and “dog-tooth” spar. For an extensive review of the types of speleothem that have been observed, see Hill and Forti (1997).

Speleothems are used in a multitude of ways to explore past environmental conditions, perhaps the most fundamental of which is their very presence or absence. Deposition of speleothems relies on sufficient water supply and soil CO2 to enable dissolution and transport of reactants in the vadose zone to underlying caves. In arid or glacial times, conditions may not have been favorable for speleothem formation. …

I. Wendt

Papers

A three-dimensional UPb discordia plane to evaluate samples with common lead of unknown isotopic composition