Origin of the Pacific Jurassic quiet zone

Research Article| September 01, 2006 Origin of the Pacific Jurassic quiet zone Maurice A. Tivey; Maurice A. Tivey 1Department of Geology and Geophysics, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543, USA Search for other works by this author on: GSW Google Scholar William W. Sager; William W. Sager 2Department of Oceanography, Texas A Sang-Mook Lee 3School of Earth and Environmental Sciences, Seoul National University, Sillim-dong, Gwanak-gu, Seoul 151-747, Korea Search for other works by this author on: GSW Google Scholar Masako Tominaga Masako Tominaga 4Department of Oceanography, Texas A Origin of the Pacific Jurassic quiet zone. Geology 2006;; 34 (9): 789–792. doi: https://doi.org/10.1130/G22894.1 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract Understanding the marine magnetic anomaly record is critical for constructing realistic geodynamo models of global geomagnetic field, polarity reversal mechanisms, and long-term geomagnetic field behavior. One of the least understood portions of the marine magnetic anomaly record is also the oldest part of the record, the Jurassic quiet zone (JQZ), where anomalies become weak and difficult to correlate. The reason for the existence of the JQZ is unclear. It has been suggested that the JQZ is a true polarity superchron, similar to the Cretaceous normal superchron. Continental magnetostratigraphic studies have suggested that the JQZ is a period of rapid polarity reversal, of low field intensity, or both. We show results of a deep-tow survey of Pacific Jurassic crust that confirms the existence of magnetic anomalies within the JQZ. We tie Ocean Drilling Program Hole 801C (167.4 Ma) into the record and show that seafloor-spreading magnetic anomalies are present around the hole and extend to 170 Ma crust. We find a rise in reversal rate with increasing age with reversal rates over 10 rev/m.y. at 160 Ma and at 167 Ma. Anomaly amplitudes decrease in the record from 155 Ma until 162 Ma, where low-amplitude anomalies are difficult to correlate. Prior to 167 Ma, anomalies regain amplitude and remain strong until the end of our record at 170 Ma. The JQZ thus appears to be a combination of low-amplitude magnetic anomalies combined with rapid field fluctuations, which could be due to either intensity or polarity changes. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.