Latest Proterozoic Stories

By Zhu, Wenbin Zhang, Zhiyong; Shu, Liangshu; Lu, Huafu; Su, Jinbao; Yang, Wei Mafic dykes are observed in the Korla region along the northern Tarim Block, NW China. Our sensitive high-resolution ion microprobe U-Pb zircon ages, the first determined for these dykes, indicate that the mafic dykes were mainly formed at 650-630 Ma, and thus document the youngest known igneous activity associated with rifting in the Tarim Block during the Neoproterozoic. Combined with previous geochronological...

By Steve Kuchera, Duluth News-Tribune, Minn. Aug. 7--IT DOESN'T LOOK EXTRAORDINARY -- but a rock found in Antarctica by a University of Minnesota Duluth professor is helping researchers reconstruct what a supercontinent that existed a billion years ago looked like. Analysis of the chunk of granite collected by UMD geology professor John Goodge in 2005 indicate that part of Antarctica and North America were joined 1.4 billion years ago. "We got really lucky -- I had no idea what we were...

A lone granite boulder found against all odds high atop a glacier in Antarctica may provide additional key evidence to support a theory that parts of the southernmost continent once were connected to North America hundreds of millions of years ago.Writing in the July 11 edition of the journal Science, an international team of U.S. and Australian investigators  describe their findings, which were made in the Transantarctic Mountains, and their significance to the problem of piecing together...

In a paper published in this month's "˜Geophysical Journal International', Dr Graeme Eagles from the Earth Sciences Department at Royal Holloway, University of London, reveals how one of the largest continents ever to exist met its demise.Gondwana was a "˜supercontinent' that existed between 500 and 180 million years ago. For the past four decades, geologists have debated how Gondwana eventually broke up, developing a multitude of scenarios which can be loosely grouped into two schools of...

The rise of oxygen and the oxidation of deep oceans between 635 and 551 million years ago may have had an impact on the increase and spread of the earliest complex life, including animals, according to a study reported in the Proceedings of the National Academy of Sciences online Early Edition during the week of February 25 - 29.Today, we take oxygen for granted. But the atmosphere had almost no oxygen until 2.5 billion years ago, and it was not until about 600 million years ago when the...

By Shen, Bing Xiao, Shuhai; Dong, Lin; Zhou, Chuanming; Liu, Jianbo ABSTRACT- Upper Neoproterozoic successions in the North China and nearby Chaidam blocks are poorly documented. North China successions typically consist of a diamictite unit overlain by siltstone, sandstone, or slate. Similar successions occur in Chaidam, although a cap carbonate lies atop the diamictite unit. The diamictites in both blocks have been variously interpreted as Cryogenian, Ediacaran, or Cambrian glacial...

WASHINGTON -- Oxygen, key to life on Earth today, began to appear on the planet millions of years earlier than scientists had thought, new research indicates.An analysis of a deep rock core from Australia indicates the presence of at least some oxygen 50 million to 100 million years before the great change when the life-giving element began rising to today's levels, according to two papers appearing in Friday's edition of the journal Science.Previously, the earliest indications of oxygen had...

It has been 2.3 billion years since Earth's atmosphere became infused with enough oxygen to support life as we know it. About the same time, the planet became encased in ice that some scientists speculate was more than a half-mile deep. That raises questions about whether complex life could have existed before "Snowball Earth" and survived, or if it first evolved when the snowball began to melt. New research shows organisms called eukaryotes - organisms of one or more complex cells...

A study that applied innovative techniques to previously unexamined rock formations has turned up strong evidence on the "Slushball Earth" side of a decades-long scientific argument. The study appears in the Sept. 29 Science Express. The lead author is Alison Olcott, a Ph.D. student of earth sciences in the USC College of Letters, Arts and Sciences. Geologists agree that prehistoric Earth was locked in a deep freeze during Precambrian times, about 750 to 600 million years ago. They...

Boulder -- An experiment in a dry Antarctic stream channel has shown that a carpet of freeze-dried microbes that lay dormant for two decades sprang to life one day after water was diverted into it, said a University of Colorado at Boulder researcher.The results showed the resilience of life in the harsh polar environment, where temperatures are below freezing for most of the year and glacial melt water flows for only five to 12 weeks annually, said Professor Diane McKnight of CU-Boulder's...