COLLABORATIVE RESEARCH: Neogene Sediments of the San Timoteo Badlands, Southern California: Tectonic Implications Along the San Andreas and San Jacinto Faults

这项建议是为了研究圣蒂莫特奥荒地的地层学、生物地层学和地质年代学。它包含一个约12,000英尺厚的陆相沉积序列，年龄从5 Ma到0.7 Ma不等，在整个序列中产生哺乳动物化石遗骸，并包含可进行磁性地层和同位素年龄分析的岩性。矿藏，这座山。伊甸组和圣蒂莫特奥组产于一个背斜露头处，背斜向西北方向缓缓倾斜，在其西南边缘被目前活动的圣哈辛托断层截断。圣哈辛托是加利福尼亚州南部圣安德烈亚斯断层系统中最活跃的一条线，在过去的两百万年里经历了大约24公里的右滑。古水流数据表明，沉积物是从北部和东北部运移到圣蒂莫泰奥盆地的。岩石中独特的碎屑岩套与现在荒地东北方向的来源一致，也就是现在圣安德烈亚斯断层(S.S.)以东的一些方向。因此，圣蒂莫特奥岩层在空间和时间上都是理想的位置，可以促进对过去500万年来圣安德烈亚斯断裂系统各要素的滑移历史的研究。在南加州的这段时间里，这些岩层是唯一相对连续积累的层序。关于这些床的年代的详细分析从未被尝试过。年龄分析程序将包括脊椎动物古生物学和生物地层学、磁性地层学和同位素年代学。如果成功，结果将极大地提高我们尝试重建圣蒂莫特奥岩层的沉积史的能力，以及相对于该地区当时相邻的地体，重建包含这些岩层的构造块体的古希腊面貌。这些数据在解决区域滑动从圣安德烈亚斯断层链(S.S)转移到圣哈辛托断层的时间上也将是有价值的，这将提高我们评估整个圣安德烈亚斯系统何时以及如何在该地区有效地“锁定”的能力；这将加强对圣安德烈亚斯地区滑移率以及太平洋和美洲板块之间的区域剪切如何通过横贯山脉传播的当地调查的重点。

This proposal is to study the stratigraphy, biostratigraphy, and geochronology of the San Timoteo Badlands. It contains a sequence of nonmarine deposits about 12,000 feet thick that ranges in age from about 5 to 0.7 Ma, yields remains of fossil mammals throughout the sequence, and contains lithologies amenable to magnetostratigraphic and isotopic age analysis. The deposits, the Mt. Eden and San Timoteo formations, occur in well exposed outcrops of an anticline that plunges gently northwestward and is truncated on its southwestern edge by the currently active San Jacinto fault. The San Jacinto, the most active strand of the San Andreas fault system in southern California, underwent about 24 km of right slip during the past two million years. Paleocurrent data indicate that the sediments were transported to the San Timoteo basin from the north and northeast. Distinctive clast suites in the rocks are consistent with derivation from sources in those directions now northeast of the Badlands; some east of the present San Andreas fault (s.s). The San Timoteo beds thus are ideally situated in space and time to promote investigations of the slip history of elements of the San Andreas fault system during the past 5 million years. These beds are the only sequence that accumulated relatively continuously during this span of time in this part of southern California. A detailed analysis of age of these beds has never been attempted. The program of age analysis will include vertebrate paleontology and biostratigraphy, magnetostratigraphy and isotope chronology. If successful, the results will dramatically improve our ability to attempt a reconstruction of the sedimentary history of the San Timoteo beds, and palinspastic reconstructions of the tectonic block that contains them relative to the then adjacent terranes in this region. The data also will be valuable in addressing the timing of transfer of regional slip from the San Andreas fault strands (s.s) to the San Jacinto fault, will improve our ability to evaluate when and how the entire San Andreas system became effectively "locked" in this region; will sharpen the focus of local investigations of slip rates on the San Andreas, and on how regional shear between the Pacific and American plates is propagated through the Transverse Ranges province.