Wright (2004) experimented with Kulong lake water under normal surface temperature and pressure conditions to precipitate dolomites. His study offered experimental petrological evidence for primary dolomite formation. However, examples of ancient primary dolomites are rare.
a) This is a field photograph of steeply-dipping laminated dolostones sandwiched by weathered black laminites in Yuejingou. The hammer is 30 cm long. Stratigraphic-up is to the left (south). b) This is a photograph of a core containing intact interlaminated white and black laminites. c) This is a photograph of a core showing soft-sediment deformation, wavy lamination, and sharp and erosional bases of white and black laminites. Credit: ©Science China Press
A research group lead by Professor Liu at Northwestern University discovered primary dolostone formed by mantle-originated exhalative hydrothermal activities in an intracontinental rift basin in the Permian, analogous to "white smokers" on the modern seafloor. Their study offered important evidence of primary dolomite formation in geological history. See the paper entitled "Primary dolostone formation related to mantle-originated exhalative hydrothermal activities, Permian Yuejingou section, Santanghu area, Xinjiang, NW China" in Science China: Earth Sciences (No. 2, 2012).
In samples taken from the Yuejingou section and drill cores taken from the Santanghu Basin, the dolostone in the Permian Lucaogou Formation includes laminated dolomicrite (0.005-0.01 mm in size) and doloarenite (0.01-0.05 mm in size, such as K-feldspar analcime dolostone, dolomitic K-feldspar analcime laminite, microcrystalline quartz analcime laminite, and algal dolostone). They are finely (0.05-0.15 cm thick) interlaminated with lime micrite and dusty pyrite laminae that may be a product of black smokers. The interlaminites are probably the products of alternating hydrothermal exhalation of "black and white smokers" in the Santanghu lake. Alkali feldspar and analcime grains in dolostone are interpreted as having been derived from analcime phonolites and peralkaline igneous rocks.
Some analcime grains have a tetragonal trisoctahedron crystal form with embayed edges. Alkali feldspars are dominantly sanidine and orthoclase; and orthoclase commonly encases sanidine, which, in turn, is encased by analcime. The sequence reflects sequential crystallization of peralkaline magmas. The fragments of these rocks were brought up from the subsurface by hydrothermal fluid flows. These observations suggest that the lake was sediment-starved; lake water had a high temperature. Cathodoluminescence microscopy shows that the formation of ankerite and dolomite is earlier than that of calcite; ankerite and dolomite do not coexist, suggesting variable iron content in hydrothermal fluids.The 87Sr/86Sr ratios of 10 dolostones are 0.70457-0.706194, and 0.705005 on average, which are similar to the global average (0.70350). All doloarenite samples have a significantly negative äEu anomaly and a very weak positive äCe anomaly.
Jiao Xin | EurekAlert!
Oasis of life in the ice-covered central Arctic
24.10.2016 | Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung
Receding glaciers in Bolivia leave communities at risk
20.10.2016 | European Geosciences Union
Terahertz excitation of selected crystal vibrations leads to an effective magnetic field that drives coherent spin motion
Controlling functional properties by light is one of the grand goals in modern condensed matter physics and materials science. A new study now demonstrates how...
Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.
"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...
In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.
A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...
By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.
"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...
COMPAMED has become the leading international marketplace for suppliers of medical manufacturing. The trade fair, which takes place every November and is co-located to MEDICA in Dusseldorf, has been steadily growing over the past years and shows that medical technology remains a rapidly growing market.
In 2016, the joint pavilion by the IVAM Microtechnology Network, the Product Market “High-tech for Medical Devices”, will be located in Hall 8a again and will...
14.10.2016 | Event News
14.10.2016 | Event News
12.10.2016 | Event News
24.10.2016 | Earth Sciences
24.10.2016 | Life Sciences
24.10.2016 | Physics and Astronomy