Dating speleothems

dating speleothems

How are speleothems dated?

Speleothems, despite their uniform mineralogy (calcite, less commonly aragonite), occur in a great variety of forms, dimensions, and colors, and any of these can be dated by U-series methods provided their age is within the dating limit of the particular method.

What are speleothems in a cave?

Geologists refer to the mineral formations in caves as “speleothems.” While the water flows, the speleothems grow in thin, shiny layers. The amount of growth is an indicator of how much ground water dripped into the cave. Little growth might indicate a drought, just as rapid growth could point to heavy precipitation.

Why are speleothems important to geologists?

Speleothems: Cave rocks. Because speleothem growth is influenced by geography, ground water chemistry, and other factors, the record from one cave cannot serve as a record of climate change. Scientists must look for similar patterns of growth in speleothems in caves over a broad area to infer that the climate changed.

What is A speleogen?

Speleogens (technically distinct from speleothems) are formations within caves that are created by the removal of bedrock, rather than as secondary deposits. These include: Lava tubes contain speleothems composed of sulfates, mirabilite or opal. When the lava cools, precipitation occurs.

What are the prerequisites for the dating of speleothems?

As with any dating method a fundamental prerequisite is the lack of post-depositional alteration, that is, no gain or loss of isotopes within the decay chain of interest. Using state-of-the-art instrumentation this method allows dating speleothems between essentially zero and ca. 600,000 years before present.

How are speleothems formed?

Speleothems are mineral deposits formed from groundwater within underground caverns. Stalagmites, stalactites, and other forms may be annually banded or contain compounds that can be radiometrically dated. The thickness of these depositional layers or isotopic records can be used to determine past climate conditions.

How old are speleothems in caves?

Entering a cave decorated with various sorts of speleothems commonly prompts questions about the age of these formations. It is intuitive to suggest that tall stalagmites or thick flowstone took a long time to form, but until the middle of the 20th century no method existed which allowed the quantitative determination of how old speleothems are.

What do 14 C dates of speleothems mean?

In short, 14 C dates of speleothems provide only a rough estimate of their formation age and samples older than ca. 50,000 years cannot be dated using this method.

What is a speleothem?

A speleothem (cave formation) composed of long needle-like crystals situated in clusters which radiate outward from a common base. A passage that is very low.

What is a speleo-buffoon?

In order to progress through passages, cavers often need to negotiate or clear boulder chokes. Also called a speleo-buffoon or cave-buffoon, a derogatory term referring to cavers who are unprepared and make poor decisions. A specialized land trust that primarily manages caves or karst features in the United States.

What is the spleen?

Your spleen is a small organ that sits inside your left rib cage, just above your stomach. In adults, the spleen is about the size of an avocado. The spleen is part of your lymphatic system (which is part of your immune system ).

What is the role of spleen in the phagocyte system?

Spleen. As a part of the mononuclear phagocyte system, it metabolizes hemoglobin removed from senescent red blood cells (erythrocytes). The globin portion of hemoglobin is degraded to its constitutive amino acids, and the heme portion is metabolized to bilirubin, which is removed in the liver.

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