21. The source rocks which provide the heavy mineral sands determine the composition of the economic minerals. 22. The ultimate source rocks may be mafic-ultramafic rocks. 23. The brown Junggar basin, which are among the richest source rocks for oil in the world. 24. Depend on properties of Sm-Nd radioactive isotope system can provide age estimation of sedimentary source rocks . 25. Pennsylvania also has reserves of natural gas from both deeply buried source rocks and coal-bed areas. 26. These mid-Cretaceous shales also serve as source rock for reservoirs found in Paleogene turbidites and basin fan complexes. 27. A good source rock has 1 % organic material in it; an outstanding source rock has 5 %. 28. Some of the most important source rocks come from this stage, including the La Luna and Socuy formations. 29. Lacustrine deposits have gained more attention recently due to containing valuable source rocks of oil, coal, and uranium. 30. The proper source rocks have to be buried to the proper depth for the proper length of time.
